"Stonechat" is a periodical magazine for members of the Horsham Geological Field Club, edited by John Morton. Here are some extracts from recent editions:-
   

Marie Stopes - Howard Falcon-Lang, Earth Sciences, University of Bristol

Marie Stopes was one of the most flamboyant and influential figures of the 20th century (Guardian readers voted her Woman of the Millennium in 1999). Her landmark sex manual, Married Love, was nearly never published. On receiving the manuscript, one prospective publisher responded that if women demanded too much in the bedroom, they wouldn’t find a husband at all (it was, after all, the First World War and men were in short supply). She later courted huge controversy over her birth-control clinics (the Catholic Church, in particular, argued that they would surely undermine the fabric of decent society). Indeed, in 1940, an Australian MP made the extraordinary claim that the British Empire had three enemies - Hitler, Goebbels and Stopes - and the greatest of these was Stopes!

Despite her international renown, few people realise that Stopes’s initial training was in geology, and specifically in palaeobotany (the study of fossil plants). With a distinguished scientist for a father and a well-known feminist for a mother, there must have seemed an ironic inevitability to the way her bipolar career unfolded. In 1901, she accidentally gained first class honours degrees in both geology and botany after only two years of study at the University of London (she had entered for the exams a year early as a practice run for her finals). A period of doctoral research in palaeobotany then followed at Munich University. By 1910, the year when her popular textbook Ancient Plants hit the bookshelves, she was already widely acclaimed as the rising star of British geology, aged only thirty.

In 1911, Stopes became embroiled in a geological controversy concerning a fossil site in eastern Canada known as Fern Ledges. Hewn by the world’s highest tides on the Bay of Fundy, these beds of primeval rock had yielded some of the oldest known remains of land animals and plants. But just how old were they? Did they date from the Carboniferous - the time when the coals were laid down - or were they part of a much older rock succession? This would have hardly mattered had it not been for the fact that opposing factions within the Geological Survey of Canada were openly confronting one another in print. This simply would not do, and so the powers that be brought in Stopes as a ‘hired gun’ to sort things out.

Few people realise that Stope's initial training was in geology. Stopes’s Fern Ledges monograph was quickly recognised as a classic of its genre - as clear, incisive and influential today as when it was first published in 1914. It effortlessly sliced through decades of sloppy thinking, proving once and for all that these famous rocks were no older than the Carboniferous Coal Age. I have long been fascinated by Stopes, and in August 2005, was afforded the spine-tingling pleasure of undertaking palaeobotanical research at Fern Ledges myself. Ironically, the trip was paid for by a Matthew Fellowship, the legacy of George Frederic Matthew, a Canadian geologist who had consistently opposed Stopes’s conclusions.

Much remains to be discovered at the Fern Ledges, not just in the rocks themselves, but also in the writing of Marie Stopes. A recent conference on Women in Geology (28 November 2005) sponsored by the History Group of the Geological Society of London (HOGG), gave me the opportunity to delve deeper into her work. Stopes must have been a hugely versatile thinker; in fact, she was finishing her Fern Ledges monograph at the same time as penning the first draft of Married Love - an interesting piece of multitasking if ever there was one. Nevertheless, there was clear continuity between the two works. As a piece of science, the Fern Ledges monograph was, in its own way, revolutionary - boldly challenging geological conventions.

One aspect that has particularly impressed me is the way that Stopes always ‘told it as it is’. Science is meant to be impartial, but many of Stopes’ palaeobotanical colleagues tried to improve their fossils by tweaking photographs or drawing extra details on specimens. Never a shrinking violet, Stopes took a clear and outspoken stance against this widespread but dubious practice, declaring it simple fakery. Even more significantly, she was careful to separate observation from interpretation, which is the essence of good scientific method.

Unlike many female scientists of her era who lived in the shadow of men, often failing to get the recognition they deserved, Stopes dominated her field from the outset. She left geology at the height of her powers, and by her own choice; even before the ink was properly dry on her Fern Ledges monograph, she was moving into radically different spheres. Hot on the heals of her sex manual in 1918, her first birth control clinics opened in London in the early 1920s - the most enduring of her many legacies. Some have snidely argued that she used her doctorate in palaeobotany to tacitly provide medical credibility for these advice centres; more likely, I suspect, she just let others make their own assumptions.

In the same year that Stopes worked at Fern Ledges, another young palaeobotanist, Walter Bell, was cutting his scientific teeth at Joggins, a fossil site a little further around the Bay of Fundy in eastern Canada. Bell rose to be one of the leading palaeobotanists of his day, but none of his many monographs matched Stopes’s work for quality. One cannot seriously talk about missed opportunities when discussing an iconoclastic figure like Marie Stopes, but it is only natural to wonder what she might have achieved had she devoted her whole life to geology. Equally, of course, I wonder what kind of society we might live in today, if she had.

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Research at Smokejacks: a temporary pond ostracod fauna in the Early Cretaceous of S.E. England.

The talk on March 11th was given by Dr David Horne who is currently working in the Department of Geography, Queen Mary College, University of London. David began by acknowledging the important research made by Eleanor Nye, Susanne Feist-Burkhardt, Andrew Ross and John Whittaker, all of the Natural History Museum, London.

Ostracods are small bi-valved cretaceans found in oceans and fresh water. The latter occur in lakes, ponds, rivers and often in temporary shallow pools. The shells of these creatures have been preserved in sediments and have been recorded back to the Ordovician 500mya. We were shown images of examples taken from the Clock House pit, all from the Early Cretaceous period. The shell has pits, lobes and spines and is hinged at the upper margin. The eye spot could clearly be seen from the slides shown. Modern non-marine ostracods belong to three main groups.

a) CYPRIDOIDEA e.g. Mantelliana

b) CYTHEROIDEA e.g. Fabanella and Theriosynoecum

c) DARWINULOIDEA e.g. Darwinula and Alicenula

The Cythereroideans are the most diverse marine ostracods today and we were shown several examples. These can crawl but do not swim. The Cypridoideans are the most diverse non-marine species found today and are sexual and asexual. The modern Eucypris is a type of ostracod which is good at swimming, enabling it to reach food and escape from predators.

The life-cycle can be three to four years or as little as a few weeks. The longer life life-span can be attributed to their ability to resist drying out or freezing. The eggs can survive low temperatures for up to thirty years or so. Brood care has to be in permanent water. The eggs of some varieties appear to have been dispersed over great distances. This could explain how the same species can be found living in isolated colonies in South Africa, as well as in the Hebrides and Finland. In this case it is suspected that the migration pattern of the Arctic Tern is responsible for dispersion over such a long distance. One egg produced by parthogenesis can start a new population.

The Cypridoideans, the eggs of which were desiccation-resistant, expanded greatly in the Jurassic. It was the study of these at Smokejacks to which David then turned our attention.

After the discovery in 2001 by our own Geoff Toye of the partial skeleton of an iguanodon, the associated sediments were collected by a team from the Natural History Museum. Apart from the iguanodon remains, the sediments contained a turtle plate, crocodile scute, Lepidotes scales and two species of ostracod. These were Cypridea clavata and Cypridea bogdenensis. Previously Smokejacks had been known for the lack of ostracods, therefore these finds were of particular interest. The sediments also revealed well preserved non-marine pollen and spores from marsh dwelling plants.

Early Angiosperms and a green fresh water alga suggest temporary pond water. The Early Cretaceous climate here was warm/tropical and probably helped to create an algal bloom. Anderson’s taxonomic scheme suggests that Clavata and Bogdenensis are of the same species but with minor differences.

The ostracods which occurred in the iguanodon bed existed in a temporary pond on a marshy floodplain in which a bloom of green algae occurred, possibly caused by the decaying remains of the dead dinosaur, but before the carcase was completely buried.

Dr. Horne then answered questions from members which certainly demonstrated how interesting we all found his talk had been.

Valerie Bell

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The Early Geological Work of Charles Darwin

Our April meeting enjoyed a most interesting talk by Professor Peter Worsley of Reading University. Darwin had shown an early interest in geology, collecting stones and pebbles before he was ten years old. Having first studied medicine and then considered the priesthood, he took up Geology at Cambridge under the eye of Adam Sedgwick, the Woodwardian Professor. He was intrigued by a large piece of granite, the Bellstone, weighing nearly a ton, in his home town of Shrewsbury and the mystery of how it had got there, since it was so out of place against the local red sandstone. Later, he would come to understand that this was a glacially-transported erratic, carried all the way from Scotland.

Darwin was recommended to join HMS Beagle as a naturalist and to provide intellectual company for the twenty-six-year-old Captain, Robert Fitzroy, on a scientific survey of South American waters. In preparation for this, he visited North Wales with Adam Sedgwick, who showed him how to recognise the structure of the geology of the country and identify fossils and igneous and sedimentary rocks.

The Beagle had, in fact, made an earlier voyage, discovering and naming the Beagle Channel, just inside Cape Horn, and exploring the Straits of Magellan, north of Tierra del Fuego, which provided a narrow but sheltered route avoiding the notorious rounding of the Horn. Its Captain, Pringle Stokes, overcome with the desolation of the place, committed suicide at Port Famine on Tierra del Fuego. The very young Robert Fitzroy was made temporary Captain and took the ship back home and with it a small number of the natives, whom they deemed to be savages, for religious instruction. It rapidly became obvious that this was an mistake and Fitzroy insisted on the natives being repatriated on the second voyage.

The departure of the Beagle on its second voyage had been delayed for three months because of adverse weather, but finally she left for what turned out to be a near five-year voyage in late December 1831. Her first landfall was at St. Jago in the Cape Verde Islands, where Darwin noted a line of oyster shells well above sea level. He recalled Charles Lyell’s observations on the subject and realised that with this sort of observation he might well be able to make an important contribution to geology.

While the Beagle ran back to Bahia, as part of its survey programme, Darwin spent some three months exploring the hinterland of Rio de Janeiro, where he found the geology exciting. On the ship’s return, he was advised that the surgeon-naturalist had resigned and gone home, leaving him as the sole naturalist to the expedition. While in Montevideo, he received by post a copy of the second volume of Lyell’s Principles of Geology, which argued against the evolution of life.

Along with his botanical specimens, he was looking for fossils, and in Patagonia he found a huge skull and other remains of a megatherium, an extinct sloth-like mammal, together with fragments of fossils of at least six other mammals. As the ship reached the southern tip of South America, Fitzroy took it up the Beagle Channel, where he disembarked the natives he had brought from England, together with an English missionary. A settlement was established on the shore of the channel with prefabricated buildings, but when the ship returned nine days later it was found that the native people had systematically looted it and the English missionary conceded defeat and rejoined the Beagle.

To continue his survey, Fitzroy set sail for the Falkland Islands, where Darwin was delighted to find early sandstones, similar to those being studied at home by Sedgwick. He realised he had the chance to take home samples for comparison of similar rocks from the other end of the Atlantic. After returning to Montevideo, they eventually turned south again, Darwin taking several opportunities, while the ship continued its surveying, to trek inland in his search for rocks and fossils. Following another call at the Falklands, they finally rounded the Horn and started up the west coast of South America and wintered at Valparaiso.

Resuming their surveying gave Darwin the opportunity for more forays inland and he witnessed at least one volcanic eruption and experienced an earthquake and the destruction it caused in Concepcíon. He found a mussel bed that had been lifted several feet above high tide and recalled Lyell’s report of the damage caused by molluscs on the three majestic cipolin marble columns of the Temple of Serapis at Pozzuoli near Naples, now well above the water table, proving that subsidence followed by uplift close to Vesuvius had occurred. He climbed into the Andes and crossed from Chile into Argentina. En route he came across a grove of fifty fossilised trees 7000 feet above sea level in a sandstone escarpment. He was able to reason out that these trees had once stood on the shores of the Atlantic, now 700 miles to the east. The land had subsided, drowning the trees and burying them in sand and silt, then slowly risen to its present height. The obvious time factor involved was in contrast to what the church had taught him during his studying for the priesthood that Noah’s flood had occurred only some 5000 years earlier.

While the Beagle continued surveying the coast, Darwin trekked north on foot, enduring great hardship but thoroughly enjoying his geological discoveries. He rendezvoused with the ship at Lima and at last they set sail for the way home. Their first call was at the Galapagos Islands. Apart from his famous observations of the wildlife, Darwin was more than interested in the geology. He was surprised to find hardly any sedimentary rocks but observed numerous inert volcanic cones and wide areas of lava. After five weeks they left for Tahiti, 3200 miles away, where Darwin hired a guide for a two-day climb into the volcanic peaks. They then moved on to New Zealand and, after a fortnight, to Australia.

One of the tasks the Admiralty had set Fitzroy was the study of coral atolls

Homeward bound, they called briefly at St. Helena, where Darwin found shells at 2000 feet which had been assumed to be from marine creatures, but he was able to recognise them as being from extinct land species.  Darwin examined the red volcanic cones of the ‘cinder in the ocean’, Ascension Island. Then, with short stops at Bahia to check Fitzroy’s longitude readings and in St. Jago and the Azores to pick up water and provisions, the Beagle finally dropped anchor in Falmouth four years and nine months after she had left.

Darwin had written ahead to ask his friend, John Henslow, to put him up for Fellowship of the Geological Society. He had found proof for himself of Lyell’s ideas that the World was an accumulation of slow, natural changes. He had, through his letters home to Sedgwick, already vastly improved the knowledge of South American geology. Darwin met Charles Lyell, who introduced him to Richard Owen, who was at that time Curator at the Royal College of Surgeons. Darwin’s specimens were excitedly received in London and Cambridge and he continued his interest in geology.

A year after he had returned from his voyage on the Beagle, he took a holiday in Scotland, visiting, among many other places, Glen Roy, north-east of Fort William, where he was intrigued by the famous ‘parallel roads’. He convinced himself that these three terraces, which ran right round the Glen at two hundred and one hundred foot intervals, to be ancient sea beaches, illustrating his global geological theory that the land here had risen in three stages. In fact, today they are understood to have been formed by a glacier during a recent Ice Age.

This article was inspired by Professor Worsley’s talk and greatly assisted by Adrian Desmond and James Moore’s book Darwin, published in 1991.

John Morton

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Darwin's trouble

The 3000 or so rock and mineral specimens that Charles Darwin sent back to England during his Beagle voyage languished in a basement at his home, Down House in Kent, until a grant from the Heritage Lottery Fund enabled them to be properly recorded and curated at the Sedgwick Museum of Earth Sciences at the University of Cambridge. An exhibition displaying them is due to open in 2009. This behaviour confirms that Darwin was a typical geologist. In his later years, he was afflicted by a mysterious illness. I wondered if the two facts were related

If your field-tripping rocks

End up stashed in a box,

And the box is put somewhere secure,

And if soon many more

Are put into your store,

You’ve an ailment for which there’s no cure.

After years of collecting,

If you find you’re neglecting

To remember which basement they are in,

Your ailment’s the same

(Whatever its name)

As the one that afflicted Charles Darwin.

Gordon Judge

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William Smith’s improvements to the fresh water supply of Scarborough in 1827

In the early nineteenth century, Scarborough was, as now, a popular resort with a large influx of summer visitors. There was therefore a great need to provide an adequate supply of fresh water for them. Through his understanding of geology, Smith had the bright idea of blocking up a local spring and using the aquifer behind it as a natural reservoir, which succeeded in penning up for summer use a huge amount of water collected during the winter months. He also had constructed, as a forward reservoir in the town itself, what was believed to be the largest covered receptacle for water in England.

Leaving behind his financial problems in London, Smith took up residence in Scarborough in 1820. He had a number of engagements with the authorities in the town, almost in effect becoming Borough Engineer. He was particularly interested in improving Scarborough’s water supply.

Water had been brought into Scarborough through a channel as early as 1319 by Franciscan friars, who tapped a spring in the hills west of the town and passed it on to two troughs known later as the Middle and Lower Conduits, the word referring not only to the supply channels but also to the wells and pumps they served. (Incidentally the Oxford English Dictionary states that the word spelt ‘conduit’ is pronounced ‘conditt’). In 2005 an archaeological investigation into an old well in the north-east corner of the area now known as Falsgrave Park (but which in the 18th century was known as Conduit House Allotment) on the south-western edge of the town led to the suggestion that this was the site of this original Franciscan spring.

In 1339, springs higher up the slope were tapped to add to the supply for another conduit (the Upper one) on the corner of St. Thomas Street and Newborough. This second conduit head, which had consisted for centuries of a spring and collecting tank or well, had become the Conduit House Close. A small stone building (MR 875072), probably built in 1773, still exists and is thought to be on the site of the second spring tapped by the Franciscans. It is shown on the current Ordnance Survey map to be at a height of 140 metres (459 feet) above sea level, a considerable drop to the conduits in town. It is remarkable too that the distance from Falsgrave Park to these supply points is at least a mile and a quarter and a stone-built channel carried the water without, apparently, undue leakage. These conduits were still in use in Smith’s time, although the channels had probably been replaced by lead pipes in the 17th century. Smith was most certainly conversant with the strata of Spring Hill and the aquifer responsible for the water supply. The Cornbrash would almost certainly have been his marker horizon, with Coaly Grit below it, Kelloways Clays and Sandstones above. 

The resident population of Scarborough in 1821 was 8188, a 27.7% increase on the figure for just twenty years earlier. There was a considerable influx of summer visitors, in particular for the Spaw [spa] Water Drinking Season, and the provision of an adequate supply of good quality water was an important requirement. People were beginning to use water for washing more frequently than in the past and were looking to a reliable supply that they did not have to draw from wells in buckets. A complaint from an apprentice in 1826 states that the shortage of water in Scarborough was severely felt and that, although a new spring had recently been found, people had to wait up to three hours before any water flowed through. The new spring was almost certainly that utilized by William Smith in 1827, of which more later.

Smith was Agent for Sir John Johnstone on his estate at Hackness, seven miles north-west of Scarborough. He was also a Consultant Engineer and Adviser on Drainage and Irrigation Projects for the town. He was asked by the Commissioners to advise on the water supply and he recommended that a reservoir be built in Workhouse Yard (now Chapman’s Yard, off North Street).

In 1827, Smith wrote to Sir John Johnstone:

‘Dear Sir John,

‘Your brother having kindly favoured me with a call and your address, I beg leave to trouble you with some account of my proceedings during your absence. Ever since you left I have been almost daily employed by the commissioners for improving the town of Scarborough which suddenly became a truly improving place. The church is rising fast and a grand Spaw walk is forming at a great height along the frightful slope of the Spaw cliff close against the sea is already united by the immense platform required for constructing an Iron bridge of 5 arches 70 feet high. This grand project - suddenly started by subscribers from York, commenced in November and is rapidly proceeding.' [This fine bridge, dated 1827, is still in use as a footway crossing Valley Road opposite the Rotunda Museum. Although he does not say so, Smith had surveyed the site for it].

In addition to this stupendous bridge, there is already constructed what some have called "a magnificent Reservoir" and in addition to this public work lighting the town with gas is seriously contemplated, my share in these great works though least seen is considered, with great satisfaction, not the least useful. The Reservoir situate in the high part of the town, is I expect, the largest covered receptacle for water in England. It consists of a brick built cylinder sunk near 20 feet beneath the solid ground, 40 feet in diameter covered with a brick dome 40 feet span and 20 feet high, the whole of which immense arch consisting of 250 tons of brickwork turned without centreing or any woodwork to support the bricks, was closed the 20th of January and we are now fast proceeding with the appendages requisite for filling it and a better distribution of water in the town. Nearly the whole of this building containing 120,000 bricks is underground or covered with a puddle and strong bank of earth giving it altogether the appearance of an immense Tumulus. `It will contain 4,000 Hogsheads [one hogshead = 52·5 imperial gallons = 2370 litres] of water, but the other Reservoir (wholly unseen) made at my suggestion in the hills at a trifling expense to pen up in the rocks 5,000 Hogsheads of water is by far the most curious and perhaps the most useful practical hint hitherto deduced from Geology. It has so far exceeded our expectation of pinning up at the calculated height of four feet the above quantity that it has risen 12 feet and thence reasonably expected to produce in the next Summer fifteen thousand Hogsheads of water – So far, I think I was never in my life more usefully employed.

Your greatly obliged servant,

Wm. Smith’

Some of the new reservoir must have extended above ground level, as it is marked on the first edition Ordnance Survey map of 1853. Only a dozen or so years ago the Town Council approved building on Chapman’s Yard and it is a tragedy that no trace of the reservoir remains, it having disappeared under the premises of a sports equipment shop, but its location is reflected in the name of an adjacent narrow alley called Waterhouse Lane. However, during construction of the retail premises, archaeological monitoring was carried out by Birmingham University Field Archaeology Unit. They suggested that the 1827 reservoir was constructed to supply the nineteenth century workhouse, whose position has been recorded in the northern area of Chapman’s Yard, extending into the St. Thomas Street development to the north-west. Smith’s letter to Sir John Johnstone quoted above would seem that it did a great deal more.

Though, again, he does not say so, Smith was responsible for the construction of the reservoir. He states that it would contain 4000 hogsheads, which amount to about 210,000 gallons or 956,000 litres. Per person usage at the time was probably a basic requirement of 25 litres a day, so the reservoir in the town would have been enough to provide for 38,240 people or about four times the resident population – today we would use about 200 litres per person per day - our local utility, Southern Water, estimate usage of 80 litres for a bath (or 30 litres for a shower), 10 for flushing a toilet, 80 for a washing machine cycle, 35 for a dishwasher and 1000 litres per hour for a hosepipe.

The reservoir’s purpose was to prevent waste from the newly-discovered spring, which ran continuously to the three public wells. At night, when these were not in use, they became full and the water overflowed. By diverting the spring into his new reservoir and putting a stop valve on the outflow, Smith was able to allow the level to rise when water was not in demand and provide a better and more economical supply when needed. The reservoir emptied into a conduit, which in turn served the three established outlets, on the corner of St. Thomas Street and Newborough, by the market on Leading Post Street at the western end of St. Sepulchre Street and by the Butter Cross. (This last lost its crosspiece sometime in the distant past, but it is believed to have formed part of the entrance to the old Borough in the 1200s. The earliest actual reference to is dated 1395). These conduits also supplied pumps outside the houses. An early water supply had come from a spring feeding the Damyot Stream, which originated in what is now Albemarle Crescent and flowed eastwards under the current site of the Butter Cross in Low Conduit Street at the eastern end of St. Sepulchre Street and out into the sea by today’s Lifeboat Station. 

Three weeks after his letter to Sir John was written, a paper by Smith was read to the Yorkshire Philosophical Society by its President, the Rev. William Vernon. It begins with a short treatise on the desirability of conserving water, and goes on:

`In the month of May last a small quantity was found to issue from a bore hole made several years since for draining the land. On cutting an open channel up to this, the discharge increased and at the depth of nine or ten feet amounted to twenty-four hogsheads [5,700 litres] per hour. This encouraged them to proceed; the channel under my direction was deepened four feet, when the discharge became for some time fifty or sixty hogsheads [13,500 litres] per hour. Suspecting from an intermediate and subsequent diminution that we had drawn off a confined stock of water, and that the regular run of the spring at the end of a dry summer might not be found sufficient, I suggested the propriety of damming up the produce of this spring for summer use, as the previous supply was more than sufficient for the town in winter.

`The circumstances were favourable for the purpose, as there was no other known issue of water from the rock in that hill, which is about a mile long, narrow on the top, and insulated in all the upper part of its stratification. The same rock is not opened or known anywhere else on these hillsides, but in a deep valley which separates the insular hill from the main and higher hill of Falsgrave Moor. In the upper end of that valley a spring was opened several years since in the same kind of rock, and was brought with a declivity of thirty or forty feet round the south end of the insulated hill, near to and high enough to run into the opening made to the new spring. This was sufficient to prove the general rise of the rock westerly in the base of the insular hill, and beneath an isthmus connected with the main ridge of Falsgrave Moor and Seamer Beacon.

‘The rock in which the spring was found is a yellowish fine-grained crumbly sandstone, in thick beds, with open irony joints, the same as in the cliff south of Scarborough Spa. From the quantity of carbonaceous matter in it, it is here called "coaly grit". This sandstone, with its overlying and alternating clays, is analogous in position to the clay and sand and sandstone between the cornbrash and great oolite rocks. At the depth of ten feet the rock was found covered with a regular clay about four feet thick; on this a mark of coal, and a thin bed of hard stone full of imperfect vegetable impressions; and up to the surface a very tenacious slidden clay.

‘The rock was found, by boring through it, to be ten feet thick, lying on clay. The channel excavated up to the spring about thirty or forty yards long and fifteen feet deep, at the upper end was entirely in a very tenacious clay partly diluvial, with a few rounded stones in it deeply covered by slidden clay. Within four feet of the edge of the rock lay gravel (deeply covered also with slidden clay), consisting of large and small boulders of whinstone, granite, mountain-limestone, etc., which gravel, between the clay and the face of the rock tapered downward "to nothing" in the bottom of the excavation.

‘About two yards within the edge of the rock (which was nearly as upright as the edge of a wall) a basin six feet in diameter and four feet deep was excavated, to receive the water flowing from the joints of the rock. Cast iron pipes branching from the main line of pipes were laid up to this basin, to receive the regular flow of the spring, which before the end of summer was reduced to less than six hogsheads per hour. The clay channel, in the bottom of which the pipes were laid, was refilled with clay and puddled, so that no water could pass from the rock but through the pipes. The end of the last pipe was closed, and a vertical aperture made for receiving the run of the spring.

‘No further contrivance was required for stopping the water and damming it up in the rock, than an open vertical pipe, ground to fit tight into the aperture in the horizontal pipe, and this to a height of four feet was done by pieces of pipe, each a foot in length, tight-fitting one into another for the convenience of wholly or partially damming or drawing off the stored water as occasion might require; the water being allowed to run in at the top of the pipe.

‘After the rainy days in the beginning of November last, these short pieces of pipe were put in one after another, and found to dam up the water in the joints of the rock to the height of four feet, which from the quantity wasted last summer during the progress of the works was calculated to contain 5,000 hogsheads. The vertical pipe being since closed at the top (and lately also the main iron pipe), the whole of the water from those parts becomes forced in to the cavities of the rock, and now stands 14 feet deep at the spring, or ten feet higher than we calculated upon penning it; so that the subterraneous reservoir may contain 12,000 or 15,000 hogsheads of water. [15,000 hogsheads is about 3½ million litres or roughly enough as a very basic requirement for 143,000 people per day.]

‘This will be ascertained in the summer as it is drawn down from time to time into the new arched reservoir in the town.’

Smith connected his exit pipe to the town main and let the accumulated water down in controlled amounts during the summer season when the springs were usually sluggish. The large-scale Ordnance Survey map shows a steep ridge, about a mile long, running north-westwards from Falsgrave Moor Farm, and Spring Hill is named just south of the suburb of Falsgrave, quite close to the Conduit House Close. This is not conclusive but it does seem very likely that it is the site of Smith’s dammed-up spring. Over some fifteen weeks, this stored water would add nearly 30,000 litres per day, a considerable increase to a supply from the springs of probably not more than 113,000 litres per day for a population of about 1200 households.

The authorities have, of course, needed to keep improving the supply to the town over the years, as the population increased and water was brought into individual houses but William Smith’s work made a really significant difference at the time.

John L. Morton is the author of Strata, The Remarkable Life Story of William Smith, ‘the Father of English Geology’.

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Watersheds

Do you ever think about watersheds? Probably not. The aim of this essay is to raise their profile, as it were.

As with so many words shared with our American cousins, the term ‘watershed’ has different meetings on the opposite sides of the Atlantic Ocean. Being English, I will use our ‘English’ interpretation, which implies that the watershed is a ridge of higher land separating two river systems.

I can distinctly remember being introduced to my first watershed, and this made a conspicuous impression on me. We were at the source of the River Ribble in the Pennines. As a little northern lad, perhaps five years old, I was standing at the top of the Ribblehead, watching the Ribble flow away from me, here only a tiny beck, narrow enough for me to stand astride. I remember finding this an awesome experience.

Since then, I have been fortunate enough to stand on many of the great watersheds of the world. Surely one of the greatest of these is the ‘Continental Divide’ running atop the spine of the Rocky Mountains of the USA. (It reads better if you say "dee-varde" to yourself). What a fantastic place to stand, for instance, on the Milner Pass in Rocky Mountain National Park, at an elevation 10759ft. Here the plaque proffers the information that, to one side, the Cache de la Poudre River flows via the Missouri and Mississippi Rivers to the Gulf of Mexico, and thus to the Atlantic Ocean. Yet rain falling only an arms-length to the right, to the west, reaches Beaver Creek which flows via the Colorado River, through the Grand Canyon and into the Pacific Ocean. A separation of a stride's length hereabouts sends water to two different oceans. (Each time we have been stood on the watershed, there is a suspicious damp patch being the marker stone!)

In fact we have been fortunate to drive much of the Divide from Canada down to New Mexico, and it never fails to impress me, although it is a pretty miserable hillock in the far south.

I would suggest that watersheds are magical places, places of great significance: who knows, the Druids may have found them important places of worship.

We do have quite a number of interesting examples of watersheds in our immediate area, and yet the only way they can be identified is by examining the local O.S. map with a magnifying glass. I would like to see that state of affairs improved.

Here are some local examples of watersheds.

   1. The Colgate-Pease Pottage Road represents the boundary, that is the watershed, between the River Mole and the River Arun. This tributary of the River Mole makes its way through Buchan Park and Ifield to the Mole. To the south of the ridge, water flows down through the incised valleys in the sandstone to the River Arun.

   2. The Horsham-Rusper Road, just to the south of Rusper, travels along the watershed between the River Mole and the North River.

   3. At Newfoundout, along the road known as Southwater Street, joining the top of Kerves Lane with Southwater, there is a tributary of the Adur flowing off to the South, whilst rain falling on the plateau of Denne Hill to the north flows to the Arun.

   4. The B 2110 at Turner's Hill runs along the watershed between the Medway and the Ouse.

As we can see from these examples, a number of our local roads travel along watersheds, which is hardly surprising, given the difficulties of travel in historic times. Perhaps these were drier routes, perhaps the clay on a ridge was slightly less sticky, perhaps there was a clearer, more open view on the ridge and travellers felt there was less risk from attack by footpads and other malcontents!

The fact that watersheds are ridges meant that they were accepted as natural boundaries between parishes and even counties. Before the meddlesome Mr Heath redrew the county map of England, eliminating in the process such time-hallowed entities as the great West Riding of Yorkshire, many county boundaries were located on watersheds between our great river basins.

Why are we not more aware of the location of watersheds? There is a lack of awareness, which could easily be overcome. I would like to suggest that discreet signs could be placed along roads to indicate to travellers when they are making their way along a watershed. ‘Oh’ I hear you say, ‘do we need more visual pollution in the countryside from yet more signs?’ I agree, there is now a plethora of signs littering the countryside. Every rural public house, every minor ‘attraction’ has its location indicated from every point of the compass by the now-familiar brown signs. Yet do we not find signs showing geographical and topographical features of interest? Do they not alleviate the tedium of the journey? Surely anyone driving the M40 motorway finds it interesting to see the River Cherwell or the Grand Union Canal indicated. Many English counties do indeed label their rivers and canals. Further afield, a journey in France is made much more interesting by their practice of naming every watercourse, large or small: every ‘ruisseau gazouilleur’ is named. And surely there is the romance in the sign ‘La source de la Seine’. The Spanish even label their railways.

The sign for a watershed route could be quite discreet, quite subdued, say some 70 cm by 20 cm. I would suggest the following symbol for a watershed. It could be a filled equilateral triangle, apex upwards, upon which a few diagrammatic raindrops are falling. This symbol would occupy part of my proposed sign, and then all that would be necessary would be for the two river basins to be indicated on the appropriate side. For example, driving south along the Forest Road, from Pease Pottage, one might see ‘R. ARUN - TRIANGLE - R. MOLE’. This would hardly be intrusive but extremely informative to the geographically-aware traveller.

            Raising the profile of watersheds might have a downside: H.M. Government might take an interest. It is doubtful that they could they be used as a source of revenue, not merely water! However, never underestimate the fertile imagination of the Treasury. Then there would be scope for yet another quango to provide lucrative occupation for the great and the good, and the usual rump of failed politicians. This quango could do the vital job of overseeing our watersheds. Unfortunately 'OFWAT' has been commandeered already, perhaps 'OFWARTS' - the 'Office for Watersheds and Related Topology'. Then of course, they would need a squad of Watershed Inspectors to ensure that all was well with these features: perhaps named 'WRATS', for Watershed Regulation and Topology Supervisors'.

Anyhow, despite the risk of Government intervention, let us celebrate our watersheds, and give them greater recognition.

Peter Webster

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The Iron Industry of the Weald

Jeremy Hodgkinson of the Wealden Iron Research Group gave the February lecture at the Forest School.

Jeremy opened his lecture by showing some picturesque views over the landscape of the Weald, and invited us to note that it was remarkable that at one time this had been an important industrial area of England. It does not resemble a post-industrial landscape: no pit-heads, no slag heaps.

Yet here had been the principal iron-producing area at the time of Queen Elizabeth 1st. He pointed out that all the features necessary for iron production had been present in the Weald. There was iron ore, an obvious requirement, but in addition there were supplies of stone and clay for furnaces, wood to provide the fuel for the smelting, and flowing water to be harnessed to provide the mechanical energy for the bellows and forges.

The iron ore occurs in various deposits in the Weald. The favoured method of winning the ore was to sink a vertical shaft, and he suggested that 'bell pits' were probably not used in the Weald. Many of the shafts are so close together that any widening at the base would have been counter-productive. An historical photograph of the vertical working face in the Sharpthorne brick pit taken during the extraction of clay shows the clear outline of the back-filled mediaeval shafts in the overburden. These shafts were about ten metres deep. Some of the limestones of the Weald carry iron ore, and the inclusion of limestone when charging the furnaces assisted the formation of slag during smelting. Prior to smelting, the ore had been roasted or calcined, thus converting the various carbonates of the siderite into oxide. He introduced us to the mediaeval term 'elying' for this process.

Jeremy then turned his attention to the critical factor of fuel. Initially, when there were relatively few furnaces, the woodlands of the Weald had been able to support the demand for wood. However, when the scale of the iron-making activities increased, the supply of fuel became problematical. The introduction of the blast furnace, with its greatly increased demand, exacerbated this problem.

Jeremy then looked at the historical progression of iron working in the Weald based on information gleaned from archaeological investigations. In Roman times, Julius Caesar mentioned in his writings that there was iron production in the South of England. This was concentrated mainly in the south-east of the Weald. Production was therefore close to the ports from whence the iron could be taken expeditiously across the Channel. The agents responsible for the transport of the iron were ‘Classis Britannica’, a supply organisation whose fleet controlled the Channel.

After the Romans left, there is some meagre evidence that the Saxons continued to make iron. However, it is in the Mediaeval era that the production of iron increases dramatically. In our area, Roffey was noted for the production of horseshoes and arrowheads, and there was a major site in Crawley.

The introduction of the blast furnace revolutionised the production process, and Jeremy went on to explain the difference between the original bloomery furnaces and the blast furnaces which evolved later. He explained how the final products differ, being a function of the differing amounts of carbon retained within the metal. The iron produced by the blast furnace required further treatment, involving further reheating and hammering at the forges. This made further demands upon the fuel supplies.

Jeremy then illustrated the rise, and subsequent fall, of the iron industry, by a series of maps. In 1540 there were fifteen furnaces, but subsequently this number increased rapidly, to such an extent that skilled operatives were brought in from the Pays de Bray, a region south of Dieppe.

Some of the output survives as iron headstones and fire-backs, many of them pleasantly decorated. However, when Henry VIII was in financial difficulties and yet still wished to wage war, he demanded that cannons be produced in the Weald. The foundry of origin of many cannons can be established by the initials imprinted on them. In our local Horsham Museum, there are two cannons which bear the mark of the Brede foundry.

The iron industry of the Weald suffered a rapid decline. So that, whilst in the 1690s it was thriving, by 1756 it had contracted considerably. One of the many contributory factors was the importation of high-grade iron from Sweden, but of great significant was the pressure on the supply of wood. The iron industry eventually began to migrate towards the coal supplies located in the Midlands and the North of England.

The extensive and lively question session at the end of the talk bears testimony to the interest that had been generated by this excellent lecture.

Thanks again are due to a lecturer such as Jeremy Hodgkinson who is prepared to give up his time to speak to our Society.

Peter Webster

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Scientists through the eyes of the coelacanth

Dr Peter Foley, of the NHM give the January lecture to the club. He described himself as having a biological, not a geological, background. Thus, he suggested, he might offer a different perspective on the activities of the scientific world.

His intention would be to follow the story of the discovery of the living coelacanth, and the subsequent scientific investigations which followed that event. This story opens with the extremely creditable observation by its original discoverer, but then the tale becomes less savoury, indeed rather murky, as several of the scientists involved descend to various levels of skulduggery and scientific plagiarism.

The fossil form was described by Louis Agassiz as part of his work on the study of fossil fishes. He had access to a specimen from the Permian of Durham and described it in 1839. The name was derived from 'coela acanth' or'hollow spine', and he named it Coelacanthus granulatus, the specific name relating to the granulated scales which he noted on the small section which he had available.

Subsequently, many fossil specimens of the coelacanth have been found at various horizons, ranging from the Middle-Devonian through to the Chalk, and indeed one of the most recent fossil forms bears a Sussex name, Macropoma lewesiensis. However, the fossil record ends abruptly, and it was quite reasonable to assume that the coelacanth had been an experiment which had died out in the throes of evolution, a 'failure' in Nature's great process of evolution.

The story of its discovery as an extant fish begins on December 22, 1938. Resident in East London, South Africa, Miss Marjorie Courtenay-Latimer, was much involved with the local museum as its curator. She was in the habit of visiting the incoming fishing boats with the aim of collecting unusual but otherwise-worthless specimens from the catches. On this particular day she received a phone call that an unusual fish had been brought in by a fishing boat. On seeing it, she noted that it bore the hallmarks of a coelacanth. At this stage it should be noted that a coelacanth is quite distinctive. For instance, some of its fins are attached to lobes, and the tail is quite different from the 'conventional' fish, a goldfish for example. The fisherman noted that this creature had been rather aggressive and that he had kicked it to the bottom of the pile, so that it was not in the best of condition when she eventually saw it. Its condition was not to improve, given that, just prior to Christmas, she was unable to obtain sufficient formalin to preserve the specimen entire. She did the best that could be done in this emergency: a local taxidermist preserved the outer form at the expense of losing the internal organs.

She communicated her find with J.L.B.Smith, sending him a sketch which was, in Peter's words, rather child-like but in that respect it emphasised the important and salient features of her discovery. Smith recognised her find as a coelacanth, and named it Latimeria chalumnae, thus enshrining the name of its discoverer and the location off the River Chalumna.

Smith sent details of the discovery to various British ichthylogists who suggested that this creature was some denizen of the deep sea. However, this specimen was clearly not of such an origin. Peter suggested that there was some imperial snobbery being exhibited towards the `colonial' Smith.

Smith continued his search for another specimen of Latimeria, employing tactics such as a poster campaign and the offer of an enticing reward. Eventually there was a success, and on December 20, 1952, he received the information that a specimen had been found off the Comoros Islands. With some persistence, he was able to persuade the then Prime Minister of South Africa to provide an S.A. Air Force Dakota to fly him to the Islands. A little twist in the story occurs here, for the Comoros Islands at that time were a French dependency. Learning of the discovery, some local French scientists woke up and decided to take an interest in the fish. Fearing that an embargo would be placed on its removal, Smith whisked it away from under their noses, the time from landing to take-off being only one hour! There was only time for the French governor to be photographed with the specimen. It can safely be concluded that the French were not particularly delighted by the turn of events. Consequently they made such a furore that they were given access to the specimen, and the disgusted Smith retired from the scene, concentrating on his catalogue of South African Fishes.

As the story continues, it became clear that the local islanders had been catching coelacanth specimens for years. However the fish is of little commercial value, the flesh being heavily laden with urea and quite inedible. In fact, the local fisherman call it 'gombessa' implying that it is taboo. Since that time, a fair number of specimens have been caught and studied. The French retained control of the specimens, or thought they did. A specimen was released in 1975 to the American Museum of Natural History in New York, on the strict condition that it was not to be examined internally. The Americans took little notice of this embargo, and the recipients immediately opened it up! They made the remarkable discovery that there were five young 'pups' or Christmas, she was unable to obtain sufficient formalin to preserve the specimen entire. She did the best that could be done in this emergency: a local taxidermist preserved the outer form at the expense of losing the internal organs.

She communicated her find with J.L.B.Smith, sending him a sketch which was, in Peter's words, rather child-like but in that respect it emphasised the important and salient features of her discovery. Smith recognised her find as a coelacanth, and named it Latimeria chalumnae, thus enshrining the name of its discoverer and the location off the River Chalumna.

Smith sent details of the discovery to various British ichthylogists who suggested that this creature was some denizen of the deep sea. However, this specimen was clearly not of such an origin. Peter suggested that there was some imperial snobbery being exhibited towards the `colonial' Smith.

Smith continued his search for another specimen of Latimeria, employing tactics such as a poster campaign and the offer of an enticing reward. Eventually there was a success, and on December 20, 1952, he received the information that a specimen had been found off the Comoros Islands. With some persistence, he was able to persuade the then Prime Minister of South Africa to provide an S.A. Air Force Dakota to fly him to the Islands. A little twist in the story occurs here, for the Comoros Islands at that time were a French dependency. Learning of the discovery, some local French scientists woke up and decided to take an interest in the fish. Fearing that an embargo would be placed on its removal, Smith whisked it away from under their noses, the time from landing to take-off being only one hour! There was only time for the French governor to be photographed with the specimen. It can safely be concluded that the French were not particularly delighted by the turn of events. Consequently they made such a furore that they were given access to the specimen, and the disgusted Smith retired from the scene, concentrating on his catalogue of South African Fishes.

As the story continues, it became clear that the local islanders had been catching coelacanth specimens for years. However the fish is of little commercial value, the flesh being heavily laden with urea and quite inedible. In fact, the local fisherman call it 'gombessa' implying that it is taboo. Since that time, a fair number of specimens have been caught and studied. The French retained control of the specimens, or thought they did. A specimen was released in 1975 to the American Museum of Natural History in New York, on the strict condition that it was not to be examined internally. The Americans took little notice of this embargo, and the recipients immediately opened it up! They made the remarkable discovery that there were five young 'pups' or foetuses within, each with an associated egg-sac. Presumably the French were less than pleased at being pre-empted in this fashion

After the Comoros had acquired their independence from France, other nationalities were allowed in to further the research on the coelacanth. Two Germans, Frike and Schaur, devised a submersible from which they were able to make further investigation. It is now known that this fish is a carnivore, resides in caves which occur in volcanic rock, has reflective eyes for greater sensitivity, and has one feature which will be important later in the story - each individual has a unique pattern of white spots. A distinctive feature of its behaviour which has been observed is its practice of making 'head stands'. It has been shown to have an electro-receptor organ in its snout: and can make use of this for the detection of prey.

So what of their distribution? Artistic artefacts found at various places around the globe might depict a coelacanth, so are they known from other areas? However, in 1998 specimens of coelacanth were obtained from the seas around Sulawesi, Indonesia. It was initially discovered by an American marine biologist, Erdmann, who sent samples to Texas for genetic examination. However, the Frenchman, Laurent Pouyaud, happened to be in the vicinity. With the help of some Indonesians he was able to make the genetic tests immediately. Against all the usual scientific conventions, and displaying exceedingly bad manners and perfidiousness, he stepped in and named it Latimeria menadoensis, pre-empting Erdmann.

Yet more perfidy was to come. Erdmann had submitted photographs of his discovery to the journal Nature. Some years later, a photograph which it was claimed had been had lost, of a coelacanth, was submitted by three Frenchmen, Seret, Pouyaud and Serre, to justify their claim that indeed it was they who had discovered the first specimen from Indonesia. However, a sharp-eyed editor on that journal noted that the photograph submitted by the Frenchmen showed a specimen of a coelcanth, mounted on a slab alongside other fish, which was identical in every way to that submitted by the American. At this stage it needs to be remembered that each individual Latimeria has a unique pattern of white spots. These spots were identical in both photographs, which rather gave the game away! The forgers had even lacked the wit to do a simple manipulation on a digital image. The Frenchmen were subsequently disgraced professionally.

Peter then returned to the more savoury part of the story, the actual science, and the questions which have been raised. How different are the Comoran and Indonesian species, how did they diverge, when did they diverge, how were they transmitted across the Indian Ocean?

He gave us some insight into the use of the molecular clock and its application for establishing the elapsed time since species have become separate. If the calibrations are correct, a timespan of 40 m.y.b.p. is a possibility. It is thus possible for the tectonic opening of the Indian Ocean to be of significance here.

This was yet another fascinating lecture. The twin strands of the sequence of events in the discovery of this 'living fossil' maintained interest. There was the straightforward sequence of events, but intertwined with that strand is the story of scientists who were prepared to bend the rules to further their own ambition.

I would like to thank Peter Foley for his talk, I note with interest that he has offered to come to the club again. I'm sure he will be invited!

Peter Webster

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The Geology of the Arun Basin

The lecture for November 2008 was my interpretation of how I perceived the interaction between the Geology of the Arun Basin and its effects on our local landscape, land use and history. I was influenced in the choice of topic by several factors. I have lived in Horsham for 30+ years, and my wife, Dorothy, and I walk the countryside in this area a great deal. The digital camera now encourages the taking of many photographs, and they can be examined that evening rather than when the roll is finished three months later, and their relevance is lost and forgotten.

A further factor in putting this talk together was my access to Google Earth. This software, that is available on the Internet, enabled me to generate exceedingly realistic 3-D 'aerial' images illustrating the topology of the area, without access to a private Cessna. The output is far superior to the alternative, mere sketches and diagrams. My aim was to illustrate the influences that Geology has had on a wide variety of factors, such as topology and landscape, transport, land use and industry to name but a few.

I took the Arun Basin to be limited by the Greensand ‘Surrey’ Hills to the north, the Horsham - Rusper road to the east, by the South Downs to the south, and to the west the upper reaches of the River Rother. I structured the content of my talk by following the progress of the Arun, which flows over the sequence of deposits of the Cretaceous period, from the oldest in our area, the Tunbridge Wells Sandstone, to the most recent, the Chalk. Diversions from the route of the Arun took me to the Greensands of Leith Hill, drained by the North River, and to the Rother.

The Arun rises in St. Leonard's Forest, just to the east of Horsham, on the rump of the Forest Ridge which occupies the central E - W axis of the Weald. The beds here are the Tunbridge Wells Sandstones, comprising sandstones interspersed with layers of softer clay. A number of rivers have their origins hereabouts hereabouts: the Mole, the Medway, the Sussex Ouse, the Adur and, of course, the Arun. The watersheds are also well-delineated, such as that between the Arun and the Mole along the Colgate - Pease Pottage Road. In particular, the streams flowing southwards into the Arun have cut gills, long narrow valleys, a consequence of interspersed beds of harder sandstone and softer clay. The presence of the mediaeval iron industry illustrates the influence of Geology on an area. The sandstones of the Forest are iron-bearing, but this in itself would not have led to the establishment of the major industry of its time. Indeed it was of national importance in the defence of the Realm. Of more significance to the Iron Industry were those long narrow valleys, the gills, across which dams were easily erected. Mechanical energy was generated using waterwheels, which was used to drive the bellows and the hammers used in the various processes in the production of iron. A further factor was the large amount of woodland available, enabling charcoal to be produced to provide the necessary heat energy.

The other local stone deposit is that of Sussex Marble, synonymous with 'Paludina Limestone'. This is not, of course, a metamorphosed 'marble', but a deposit containing the calcite-filled shells of the gastropod Viviparus fluviorum. It takes a good polish, and has thus been much employed for ornamental stonework, for instance, in memorials in the Wealden churches, and for many of the fonts to be found in our area.

Of interest is the picturesque Horsham Cricket Ground, given to the Club in 1851, it sits neatly on an ancient terrace of the Arun, a naturally-prepared plane area and most suitable for the game. Again this is a function of the local geology, as the Arun has been hemmed in by Denne Hill leading to the formation of that terrace.

Moving northwards we looked at the Lower Greensand around Leith Hill. This prominent ridge has a scarp facing the Weald. There is some interesting Geology in the area. The cap of Leith Hill is largely chert, and thus erosion-resistant, but beneath this cap are free-draining sandy facies and beneath those is a layer of impermeable clay, the Atherfield Clay. This has led to a succession of landslips, resulting from the familiar mechanism whereby the rainwater, collecting on the clay, lubricates the overlying sands. We made visits there after the catastrophic landslip of December 2001, taking photo-graphs so that 'then-and-now' comparisons could be shown. The road has been restored, but it looks rather insecure.

Leaving the Greensand, we examined some of the features encountered by the Arun as it passes across the Weald Clay, which are influenced by the local Geology. For example, there is a 'double bridge' across the Arun carrying the now-defunct Shoreham - Guildford railway. There is a ridge to the north in Rudgwick which had to be crossed, and the line as it was initially constructed was deemed to have too steep a gradient for safe working operation. It was necessary to raise the embankment by some four metres for a considerable horizontal length. Thus the original brick span over the Arun was some four metres too low, and thus no longer usable. An iron girder bridge was thrown over the gap to carry the line.

The clay of the Weald is sticky and heavy. Transport was difficult. The Sussex Ox, strong and biddable, was developed as a draught animal to move loads around the area. The difficulties of transportation led to the development of a number of canals in the area, which were based on the Arun and the Rother. Horsham was served also by the Baybridge Canal connecting the Adur to the Knepp Castle area. I looked at the the canal system based on the Arun, which at first extended only to Pallingham Lock. The canal was subsequently extended to Newbridge, and finally a link was made with the Wey on the completion of the Wey & Arun Canal.

The Arun meets the Greensand at Stopham near Pulborough, cutting quite a narrow valley through the resistant Hythe Beds. From here we were able to look at some of the features along the Sussex Rother. Comparing this river with the Arun, it has a different relationship with the Greensand, for the Rother flows parallel to the various beds as it moves from the west via Midhurst and Petworth to join the Arun. The Arun, of course, has had to cut a valley through the Greensands. We were able to look at the problems of erosion of the light sandy soils originating on the Folkestone Beds, now filling the bed of the Rother with sand and soil washed from the fields.

At Duncton there is a magnificent spring, from which issues some three million gallons of water per day. It is a classic example of a spring: water which has permeated through the chalk aquifer issues at a change in the permeability of the horizons. This and other chalk springs feed the Rother, enabling this river to provide a more consistent flow for the once-important canal, the Rother Navigation. The Arun, by comparison, flows largely over clay and has a far more variable flow between winter and summer. It was described by one bargeman as 'a miserable river, full of sandbanks, and with no water in summer, fast flowing in winter'.

Returning to the Arun, we looked at the wide valley which it has cut as it flows over the soft Gault Clay. Known as the 'Wild Brooks' in Sussex, both the Pulborough and Amberley Wild Brooks are havens for wildlife. Indeed, the R.S.P.B. has developed a most successful bird reserve on this flood plain, and a further bonus for the bird-watcher is that the ridges of Greensand in the vicinity provide elevated views for 'scoping over the expanse of the winter floods’. The Arun meets the Chalk between Amberley Station and Houghton. We were able to look at the changes made to the course of the Arun in that area to facilitate the building of the Arun Line. By isolating part of the Arun and making the 'New Cut', fewer, perhaps expensive, bridges were needed for the railway to cross the river.

Finally we took a brief look at the dominant location of Arundel Castle on its spur of chalk. The chalk springs associated with the Downs are important to wildlife. The Arundel Wildfowl Trust uses the spring water issuing from the chalk to provide clean water for their collections of rare and endangered wildfowl.

Finally, I looked at some of the local building stones. It is interesting but certainly not surprising that in most cases, stone from the immediate vicinity was used in the construction of churches, for example. A particularly good case to illustrate this point is Southwater Church. Built relatively recently in 1848, the records relating to its construction are still extant and these detail the quarries from which the stone was obtained. The bulk of the material travelled only a few miles, much of it coming from Stammerham only two miles distant.

Since starting this project, and looking in detail at the area, I have been astounded as to the manifold effects that the Geology of the region has had on numerous features such as local landscape, land use and history.

I would like to thank Dorothy, who has supported and encouraged me in the research for this talk. We have walked miles over the paths of West Sussex, although in such beautiful countryside this has hardly been a chore.

Peter Webster

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Great balls of mud

From the Department of Wacky Theories

(This is a piece based on a small section of a library book I've been reading. I had never heard of the idea before (although that's not saying much), so I though others might enjoy it too).

In the Meishan quarries of northern China, you can see where, as Michael J Benton puts in the title of his 2003 book¹, ‘life nearly died’. Some 251 million years ago, ninety percent or more of the species on Earth succumbed to a breakdown in the planet’s normal self-regulation systems, triggered, according to Benton, by repeated eruption of perhaps two million cubic kilometres of basalt to form the Siberian Traps. The tell-tale rock sequence shows the change from limestones and mixed sediments rich in fossils and burrows, to anoxic deeper-water mudstones, dark grey or black with undecayed vegetation and few signs of life.

The same general pattern can be seen in Greenland, where the Schuchert Dal Formation (late Permian) is overlain by the Wordie Creek Formation (Triassic). But there’s a puzzle here. If the junction marks the end-Permian mass extinction, as in China, how is it that you can find ‘‘Permian’’ fossils –– brachiopods, corals, foraminifera, crinoids, echinoids, bryozoans –– as much as twenty metres into the Wordie Creek Formation? In 1976, two American geologists, Curt Teichert and Bernhard Kummel, proposed an answer².

What had happened, they said, was that early Triassic sea-bed currents had cut into the Schuchert Dal beds and eroded out some of their Permian fossils. So why, after having been swept along by a raging current and dumped in later sediments many metres higher up in their Wordie Creek layer, was there little sign of having been smashed to pieces? Teichert and Kummel had an answer to that, too. Great balls of mud, they declared, had been swept by the Triassic torrents over the end-Permian surface, picking up delicate shells and fragments on their sticky surfaces. When these ‘armoured mudballs’ eventually came to rest in truly Triassic layers, they somehow dissolved, leaving their Permian fossils to be found 251 million years later in Triassic rocks.

Not surprisingly, their fellow geologists rubbished this heroic theorising, pointing out the ‘Permian’ fossils in the Wordie Creek Formation are preserved more or less in life position: the shells are lying on their backs, and the corals and bryozoans are upright, like little trees. Oh, and no-one had ever reported sighting an actual giant, dissolving mudball.

But Benton’s book doesn’t attempt a better solution, noting only that a more detailed examination of the Greenland sections, published in 2001, confirms the presence of the Permian ‘mudball’ species (still no mudballs, though) in the Triassic Wordie Creek Formation and reports their rapid subsequent disappearance from the fossil record. It’s implied that they might have been just a few resilient members of their species that found a way through the boundary beds of the main extinction event, only to find that they could not adapt rapidly enough to the new Triassic ecosystems.

Plausible? Possibly, and no doubt politically correct in geological circles. But not such a fun idea as Great Balls of Mud.

Gordon Judge

References:

1. Benton, Michael J. When life nearly died, Thames & Hudson, 2003. ISBN 0-500-05116-X

2. C. Teichert C and B. Kummel, Permian––Triassic boundary in the Kap Stosch area, East Greenland, Meddelelser om Grøønland, 597 (1976), 1––54

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Arthur Holmes: Number-one-top-piece-rock-pidgin-man

This was the Burmese people’s splendid version of Arthur Holmes’ job title after Yomah Oil promoted him in 1921 to ‘Up Country’ Manager and Geological Advisor. Arthur Holmes, born in Gateshead in 1890, will be known to many geologists by his 1944 textbook Principles of Physical Geology. ‘Holmes’ became an international bestseller: the first print run of 3000 copies went in a flash, and it was then reprinted eighteen times in twenty years –– the geologist’s thirty-shilling ‘Bible’ of the mid-twentieth century. The book had been written while on fire-watching duty, and had been aimed at RAF cadets. However, the final chapter of ‘Holmes’ nearly didn’t make it into the book, not because of the war but because it would challenge current dogma on the structure of the Earth.

Alfred Wegener’s ideas on ‘continental drift’, first advocated in 1912, had hitherto lacked a physical mechanism which could produce the prodigious movements he envisaged. But in December 1927, Holmes proposed such a mechanism: that differential heating of the earth’s interior, generated by the decay of radioactive elements, caused convection of the mantle (substratum as he called it). In turn, this convection could produce a force sufficient to drag continents sideways, allowing the substratum to rise up and take its place in the ocean floor. But rocking the geological boat by sticking out one’s neck made the die-hards seasick. The British geologist, Harold Jeffreys, declared that no force was adequate to move continental slabs over the surface of the globe. And on the other side of the Atlantic (what he would have still believed to be a flooded 5000-mile land bridge between Brazil and West Africa), an American critic declared ‘Holmes brings out a new thought which is even more impossible than Wegener’s.’

Arthur Holmes had always felt that the sequence of rocks should be more firmly anchored to the sequence of geological Periods. Picking up on recent developments, he thought that the decay of radioactive minerals in certain rocks could be used to set dates for the transitions from one Period to another. In 1911, just before embarking on an expedition to Mozambique, he had done this on a rock from Norway, and dated the base of the Devonian Period to 370 million years. That implied a date for the formation of the Earth which was seriously earlier than the prevailing views allowed. The Mozambique trip gave him blackwater fever, a severe and often fatal form of malaria; but he survived, and on his return he wrote a small book, The Age of the Earth, first published in 1913, to promote his ideas to a wider audience.

But, as with the ideas on Wegener’s theory which he put forward fourteen years later, the wider audience was scared of deviating too far from the current dogma. In this case it was Lord Kelvin’s Earth age of around 20 million years, based on his (revised) assessment of the planet’s cooling time. Thus, Samuel Haughton, geology Professor at Trinity College, Dublin, had felt the need to decimate to 200 million years his initial estimate (2000 million years) for the time needed for the Earth’s sediments to be deposited. Likewise, a noted American geologist of the time, George Becker, raged that it ‘must be between 70 and 55 million years’, relying on time-scales computed from rates of sedimentation and build-up of marine salinity –– the ‘hour-glass’ methods. Because of this, he concluded, ‘radioactive minerals cannot have the great ages which have been attributed to them’. And all this was despite Charles Lyells’ work on Etna’s lavas indicating an ‘immense’ age for the Earth, Charles Darwin’s calculation in the 1859 first edition of On the Origin of Species that the Chalk dome which originally spanned the Weald would have taken some 300 million years to be eroded away, and Ernest Rutherford’s 1904 dating of a piece of pitchblende to 700 million years.

Kelvin, of course, had not taken into account that radioactive emissions inside the planet were continuously adding heat. It was that very radioactivity which now seemed able to provide a definitive answer: measure the amounts, within a rock sample, of a radioactive element and of the element into which the decay process changes it. Then, if you know the element’s rate of decay, you should be able to do a back-calculation to the date of the rock’s solidification from a molten state. But, as ever, things were not that simple. Take radium, the first radioactive element to be discovered. As radium decays, it emits helium gas, so by measuring the amount of helium within a rock you should be able to deduce its age. But inevitably, some would escape in the process, making the calculated value too young. The decay of uranium to lead looked to be a better bet, but it took a while to realise that uranium has two radioactively-unstable isotopes, each of which produces a different (stable) isotope of lead, lead-206 and lead-207.

As usual, Holmes had kept abreast of work by others, and was particularly interested in analyses carried out using a mass spectrometer by Alfred Nier, a young Harvard physicist. In 1947. Nier had deduced the ages of a couple of dozen rocks, the earliest of which was a scary 2570 million years, for a pegmatite from Manitoba. Holmes recalculated Nier’s data and got a similar answer - 2480 million years. As a geologist, Holmes realised that the pegmatite was the youngest rock in a much older sequence which was the end result of a lengthy series of geological processes: sedimentation from an ancient continent in a primordial ocean; burial to depths where they partially melted and metamorphosed into a gneiss; uplift; intrusion by a series of molten lavas; and cooling, during which the pegmatite –– a coarse-grained igneous rock –– would have formed. So the gneiss it intruded must have been, what, another 500 million years old? And how old was that ancient continent which had generated the sediments in the first place?Holmes was eager to get an answer. He realised that some lead within a rock would have always been lead, in its stable form as lead-204, right from the Earth’s formation. More lead, made by the radioactive decay of uranium and thorium, would have been added to the rock from the time the Earth’s crust formed. So a uranium-containing rock might have three different, chemically-indistinguishable, varieties of lead within its minerals. The question was, how much of this ‘primeval lead’ was present in a rock?

Fortunately, one of Nier’s samples was a very ancient lead ore, galena, from Invigtut in Greenland, which contained no uranium or thorium, and very low levels of lead. Holmes assumed that this sample represented primeval lead, so that he could gauge its contribution to Nier’s other samples. He spent just over £74 on a Marchant Calculating Machine, and used it to deduce, in February 1946, that ‘the time that has elapsed since the Earth’s primeval lead began to be contaminated by radiogenic lead’ was about 3000 million years. He then added on the time he considered would have been needed for the uranium in the rocks to ‘begin to deteriorate’ within the gas cloud from which the Earth was formed. The total he arrived at –– what he called ‘the age of uranium’ –– was 4460 million years. A few months later, he revised his ‘‘contamination’’ date from 3000 to 3350 million years. (Unknown to Holmes because it was published in Russian, in 1942 the Russian, E. K. Gerling had already arrived at 3950 million years for the age of the Earth.)

The trouble was that the Invigtut sample, nor any other sample found in the Earth’s crust, actually contained truly primeval lead. Holmes realised that the solution to this conundrum might be to analyse a suitable meteorite. Another problem was that he had used up the small number of meteorite specimens which were ‘detached from a small collection which belongs to the Geological Museum of the Imperial College’.

In the 1952, Claire Patterson, a (male) research student, and his supervisor Harrison Brown, moved to the California Institute of Technology. (After he found it affecting his measurements of lead in igneous rocks, Patterson was the first to draw the world’s attention to atmospheric pollution from the lead in car exhausts.) In 1953, using top-notch equipment in an ultra-clean laboratory, he managed to determine the lead content of the Canyon Diablo meteorite –– the one that made the 200-metre deep Meteor Crater in Arizona, and suggested that his value represented that of the elusive primeval lead better than that from the Invigtut sample. That year, he and, independently, Fiesel Houtermans published figures

that put the age of the Earth at around 4500 million years. Patterson went on to confirm that the Earth and meteorites really did have a common ancestry and produced a final figure for the age of the Earth as 4550±70 million years.

Surprisingly, Holmes now argued that ‘to use the isotopic composition of lead from iron meteorites as part of the basic data for calculating the age of the Earth or its crust is unsound in principle . . . the correct procedure is to use terrestrial materials’. But he was gracious enough to admit that ‘my own attempt to solve the problem from terrestrial evidence alone leads to essentially the same result, which may be expressed as 4500±100 million . . . It is a pleasure to record my indebtedness to many younger friends who are now boldly accepting the challenge and meeting it with all the resources and superb techniques of the atomic age’.

Holmes died of bronchial pneumonia at Bolingbroke Hospital in London in September 1965. He had written: ‘Looking back, it is a slight consolation for the disabilities of growing old to notice that the Earth has grown older much more rapidly than I have – from about six thousand years when I was ten, to four or five billion years by the time I reached sixty. But it is a greater consolation to find that one’s work has not gone unappreciated.’

Gordon Judge

[Main source: Cherry Lewis, The Dating Game, One Man’’s Search for the Age of the Earth, CUP 2000. ISBN 0 521 79051 4]

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Banking problems in Japan and the Indian Subcontinent

In the last seven days Origami Bank has folded, Sumo Bank has gone belly up and Bonsai Bank announced plans to cut some of its branches.

It was announced that Karaoke Bank is up for sale and will likely go for a song. Today shares in Kamikaze Bank were suspended after they nose-dived.

Samurai Bank is soldiering on, following sharp cutbacks. Ninja Bank is reported to have taken a hit, but remains in the black.

Five hundred staff at Karate Bank got the chop. Analysts report that there is something fishy going on at Sushi Bank, where it is feared that staff may get a raw deal.

Oh yes, and the Karma Sutra Bank finds itself in an awkward position.

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Magnetite - Apatite & Related Copper Deposits in Sweden and Kazakhstan, from Oxide Lavas to Salty Water.

Our speaker for October 8th was Dr Martin Smith from the School of the Environment of Brighton University. Like many previous speakers he has had a varied career in places of learning and research in the field. The mineral research in which Dr Smith participates has been sponsored by the European Union, Anglo American, University of Alberta and the Natural History Museum.

In 1992 Hitzman defined Magnetite-Apatite deposits of the Kiruna type. These included deposits of iron oxide, copper and gold. These are in an areas of much igneous activity resulting in oxidised source rocks. They are found along large faults and one characteristic is the relative lack of iron sulphide but are associated with salt deposits (sodium). The material has a very distinctive chemistry.

The centre of research in Sweden was at Kiruna. This is situated north of the Arctic Circle on the eastern shore of Lake Luossa between the rich iron-ore Kiruna and Luossa mountains. It was founded in 1889 with the extension of the railway from Gallivare some 100 miles to the south. Mining at Kiruna developed rapidly after the railway linked it with the port of Narvik in Norway in 1902. The area is part of the pre-Cambrian shield which includes Archaeon and Proterozoic volcanics and granite. The Kiruna iron ore was formed around 1600 mya following intense volcanic activity with the precipitation of iron-rich solutions on a syenite porphyry base. The ore bed was then covered by further deposits of quartz porphyry and sedimentary rocks. The ore in this region contains a very high percentage of magnetite/apatite mix. ( Syenite is mainly formed of alkali feldspar and sodic plagioclase).

Dr Smith showed a diagram of the area indicating the iron and copper deposits. At Kirunavaara, magnetite,actinolite and titanite has been found. At Gallivare is located Europe’s largest copper mine.

In the region of Rakkurjarvi there are large bodies of magnetite in the shear zone and recorded finds here date from 1898. The magnetite breccia is so highly magnetic that compasses in passing aircraft can be affected. At Luossavara the hypersaline brine in quartz has been noted with the iron and copper deposits.

Dr Smith also spoke of the increasing tourism in the Kiruna region. Although the terrain is largely birch forest or marsh, a great attraction is that this area is very good for viewing the midnight sun.

Dr Smith then turned our attention to Kazakhstan, a country entailing a great deal of red tape to enter. The western part of Kazakhstan lies at the southern end of the Urals. This mountain range was formed by the subduction of a long-vanished ocean, bringing together the eastern edge of Baltica and Siberia. This occurred some 290-360 mya in the Carboniferous period. The rocks are volcanic and its associated deposits are younger than those of Sweden. The region is rich in minerals such as gold, platinum, magnetite and titanite. The latter occurs as an accessory mineral in alkaline igneous rocks. The area contains some of the largest copper mines in the world,

The Kachar deposits contain scapolite, quartz and granite porphyry. The scapolite crystals are large and sometimes contain a saline solution. The Valerianovka deposits contain wave ripples, corals, brachiopods, bivalves and goniatites. The latter are preserved in chalcopyrite which is the most important ore of copper.

Dr Smith asked the question:- Are the Ural skarns the same as the Swedish? (Skarns are metamorphic rocks which have derived from nearly pure limestone. They are often hot rocks for deposits of magnetite and copper sulphide). He concluded that although the Swedish deposits were of a different age from those of Kazakhstan, both shared many of the same characteristics, especially that of salty water.

Dr Smith then answered some interesting questions from the members, after which Frank thanked him for a most interesting talk.

Valerie Bell

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Sixty-five million year-old maths

Here is a way to estimate the size of the meteorite that smashed into the proto-Caribbean at Chicxulub 65 million years ago. It’s one of the four methods that Professors Luis and Walter Alvarez et al used in their 1980 paper in the journal Science. You’ll recall that dust from the meteorite’s impact can be seen today distributed around the Earth in sediments at the Cretaceous-Tertiary (C-T) boundary, and contains minute traces of iridium.

I’m afraid that, like the Professors, you have to make a number of ‘reasonable assumptions‘. Their first was that the iridium layer had been spread around the Earth by the same mechanism as the ash from a major volcanic eruption, such as Krakatoa’s 1883 blow-out; that is, by being blown high into the stratosphere where it was spread out to encircle the Earth, to be dropped a couple of years later as a fine ‘rain‘ over the ground and waters beneath. The ash which fell into the oceans from the Chicxulub impact, the Professors assumed, formed the sedimentary layer visible around the globe today.

Then you assume that whatever fraction of Krakatoa’s erupting material got into the stratosphere was also the fraction of the impacting K-T meteorite’s material that got sent up there. For Krakatoa, the volumes involved have been estimated: some 18 cubic kilometres of magma resulted in about 4 cubic kilometres of stratospheric ash, so the fraction is 0.22. (As the Alvarez paper notes, the ‘Krakatoa fraction’, 0.22, is used ‘simply because it is the only relevant number available’. It could, they admit, ‘differ seriously from the correct value as the explosions are of quite different character.’)

Next, assume that the proportion of iridium in the K-T meteorite was the same as you would find in modern meteorites, namely about half a millionth. If the mass of the K-T meteorite was M, we can now reckon, from the paragraphs above, that the mass of iridium which it spread around the place was half a millionth of 0.22 of M, or 0.11 millionths of M.

Now look at what the Alvarez group found when they analysed the C-T boundary layer in the Bottacione Gorge near Gubbio in the Umbrian Apennines of northern peninsular Italy: about 8 billionths of a gram of iridium per square centimetre of Earth surface, a major ‘spike’ compared to the general Upper Cretaceous level of around 0.3. Our Earth has about 5.1×10¹⁸ such square centimetres, so the total iridium fall from the impacting K-T meteorite must have been about 41×10⁹ grams.

We have two expressions for the same thing: 0.11 millionths of M, and 41×10⁹ grams. Set one equal to the other, and you can estimate the mass M of an impacting meteorite 65 million years ago. The answer is about 370 billion tonnes! (The Alvarez group made it about 340 billion tonnes², but might have used a different value for the Earth’s mean radius. I used the Kaye & Laby value of 6371 km.)

By contrast, the Earth weighs 5.976×10²¹ tonnes (Kay & Laby again), which is some 16 billion times as much as the meteorite. The impact would have been like a 0.45 mg flea crashing into a 7-tonne African elephant!

Gordon Judge

References:

1. Luis W. Alvarez , Walter Alvarez , Frank Asaro , and Helen V. Michel. ‘Extraterrestrial cause for the Cretaceous-Tertiary extinction’, Science, 208:4448 (6 June 1980), 1095-1108.

2. The Alvarez calculation is also presented on pp.100-101 of Michael J Benton’s book When life nearly died (Thames & Hudson, 2003). Benton uses the same data but the book declares a result (34 billion tonnes) with, confusingly, a typographical omission of the final zero!

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Great balls of mud

From the Department of Wacky Theories

(This is a piece based on a small section of a library book I've been reading. I had never heard of the idea before (although that's not saying much), so I though others might enjoy it too).

In the Meishan quarries of northern China, you can see where, as Michael J Benton puts in the title of his 2003 book¹, ‘life nearly died’. Some 251 million years ago, ninety percent or more of the species on Earth succumbed to a breakdown in the planet’s normal self-regulation systems, triggered, according to Benton, by repeated eruption of perhaps two million cubic kilometres of basalt to form the Siberian Traps. The tell-tale rock sequence shows the change from limestones and mixed sediments rich in fossils and burrows, to anoxic deeper-water mudstones, dark grey or black with undecayed vegetation and few signs of life.

The same general pattern can be seen in Greenland, where the Schuchert Dal Formation (late Permian) is overlain by the Wordie Creek Formation (Triassic). But there’s a puzzle here. If the junction marks the end-Permian mass extinction, as in China, how is it that you can find ‘‘Permian’’ fossils –– brachiopods, corals, foraminifera, crinoids, echinoids, bryozoans –– as much as twenty metres into the Wordie Creek Formation? In 1976, two American geologists, Curt Teichert and Bernhard Kummel, proposed an answer².

What had happened, they said, was that early Triassic sea-bed currents had cut into the Schuchert Dal beds and eroded out some of their Permian fossils. So why, after having been swept along by a raging current and dumped in later sediments many metres higher up in their Wordie Creek layer, was there little sign of having been smashed to pieces? Teichert and Kummel had an answer to that, too. Great balls of mud, they declared, had been swept by the Triassic torrents over the end-Permian surface, picking up delicate shells and fragments on their sticky surfaces. When these ‘armoured mudballs’ eventually came to rest in truly Triassic layers, they somehow dissolved, leaving their Permian fossils to be found 251 million years later in Triassic rocks.

Not surprisingly, their fellow geologists rubbished this heroic theorising, pointing out the ‘Permian’ fossils in the Wordie Creek Formation are preserved more or less in life position: the shells are lying on their backs, and the corals and bryozoans are upright, like little trees. Oh, and no-one had ever reported sighting an actual giant, dissolving mudball.

But Benton’s book doesn’t attempt a better solution, noting only that a more detailed examination of the Greenland sections, published in 2001, confirms the presence of the Permian ‘mudball’ species (still no mudballs, though) in the Triassic Wordie Creek Formation and reports their rapid subsequent disappearance from the fossil record. It’s implied that they might have been just a few resilient members of their species that found a way through the boundary beds of the main extinction event, only to find that they could not adapt rapidly enough to the new Triassic ecosystems.

Plausible? Possibly, and no doubt politically correct in geological circles. But not such a fun idea as Great Balls of Mud.

Gordon Judge

References:

1. Benton, Michael J. When life nearly died, Thames & Hudson, 2003. ISBN 0-500-05116-X

2. C. Teichert C and B. Kummel, Permian––Triassic boundary in the Kap Stosch area, East Greenland, Meddelelser om Grøønland, 597 (1976), 1––54

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Gold in the Emerald Isle

Our speaker for 12 March 2008 was Dr Norman Moles of the University of Brighton. Before outlining the topics to be covered, he apologised for the not surprising fact that he had no samples to display! The topics were:-

1) Prehistoric and historical evidence for sources for gold.

2) Gold mineralisation in north west Ireland.

3) Microchemical characterisation of alluvial gold.

4) A source of Bronze Age gold in the Mourne mountains.

5) The origin of alluvial gold in the Gold Mines River, Co.Wicklow.

Irish gold artefacts from the Bronze and Iron Ages are unique in Europe. 1100 pieces have been found, the majority being from the Bronze Age. The provenance of about a third is known to be a particular area. The actual years covered are therefore 2,500BC (early Bronze Age) to 500 BC (Iron Age). The examples illustrated showed the increasing skill and sophistication of the workmanship. It had been thought that much of the gold had been imported, but now it is known that it is more likely to be Irish gold from many sources. Although there is no evidence of mining at these sites, there are recorded references to early discoveries of gold in Ireland. One such reference being The Annals of the Four Masters - 1632, which refers to the discovery of gold in 1600 BC approx. and also mentions that gold was smelted in the forests south of Dublin. One source here was a gold-rich vein from Tipperkevin to Wicklow. Other historical references include the panning of gold from the Moyola River in Northern Ireland - 1652 and Avoca to Wicklow in 1753. The finding of gold in what was later called Gold Mines River, started a local gold rush in 1795. At this latter location, Ballinagore to Red Hole, was a particularly rich source. Panning here by local people lasted some six weeks before the government took over.

In the north of Ireland the presence of gold was reported before 1980 in many localities, but systematic searches did not commence until that date. An important site in the north was at Curraghinalt and Cavanacaw near Omagh. The gold here occurs in the Dalradian (Pre-Cambrian) sediments and is associated with Arsenopyrite-Stibnite veins of the Lower Paleozoic. Dr Mole then showed us a number of maps which revealed the mineralization of north west Ireland. A map was produced in 1976 by John Arthurs and in 2002 the mapping of north west Ireland was completed. It was then realised that the presence of arsenic in stream sediments coincided with the gold that is now mined in the Curraghinalt and Cavanacaw region. In 1981 exploration licences were obtained as part of the Ennex Exploration program.

In 1999 Nickelodeon acquired a licence for 0.5 million dollars and in 2003 Turnagain Resources implemented further exploration with a view to opening a mine. Curraghinalt is located in the Omagh Thrust alignment with east west faults of the Carboniferous half-graben. Together with Cavanacaw, which is five miles WSW of Omagh, serious mining began in 2000 with the production of Certified Irish Gold and the making of high-end jewellery by the company Galantas.

Dr Mole then demonstrated some of the investigations he and his colleague, Rob Chapman, of the University of Leeds have carried out. Careful study of the characteristics of gold grains may show the source of gold artefacts. Physical size and microchemical analyses were both important. Alloy composition and inclusion assemblages (transparent and opaque) were used to describe populations of gold. Samples collected were mounted up and examined with an electron microscope. Levels of copper, silver and other elements were measured. A map of the British Isles was shown which indicated in particular where high levels of silver are present.

One important source of gold in Ireland is the Mourne Mountains, north of Dublin. Richard Warner and Rob Chapman have produced a study of gold and other artefacts to prove their provenance. Some contain copper, which is red in colour but deliberate alloying was not likely. In the region, Hilltown and Ballincurry produced good samples, indicating levels of copper and silver. Irish gold has less copper than the artefacts and so Dr Mole will return in April for more exploration to find any copper-rich gold.

The final aspect demonstrated was the origin of gold in the Gold Mines River area. The source of gold in this region is in the periglacial and glacial till in the river valleys. Particular places mentioned were: Avoca, Woodenbridge and the Croghan Kinshelagh Mountains, which are the source of the local rivers. The deposits found were divided into types according to their mineral content. For example, Red Hole, being type 3, grains contain 8-14% silver. Also present could be sulphide and antimony.

The geological make-up of the Avoca area is Felsic volcanics with the intrusion of dolerite. Bedrock source in the valley is close to the alluvial cut-off point dating from the Late Tertiary or inter-glacial. The sediments are preserved in the deep valleys formed by glaciers. The general conclusion to date is therefore that the gold in the artefacts was obtained locally and not transported. Dr Mole then answered questions from members before Frank expressed heartfelt thanks for a most intriguing and interesting talk.

Valerie Bell

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Gordon's garden, again

Last year, as part of a long-overdue redesign of our garden, I dug some trenches to drain the lawn, and others to take the concrete footings of a low wall curving across its width. To my surprise, I found some interesting bits of ripple-marked Upper Tunbridge Wells Sand, and wondered what I might find if I dug up the rest of the lawn. But I sensed that my garden didn't share my enthusiasm.

I am Gordon’s garden, and although I had my say,

He’s taken not a scrap of notice, gone his own sweet way.

Not satisfied with dumping stuff he’s brought from far away,

He’s recently been eyeing me in quite a different way.

He’d noticed how my lawn becomes so boggy when there’s rain,

And dug a string of trenches filled with gravel so they drain.

(It’s ruined my appearance. Oh, he really is a pain!)

But what he found took me aback –– perhaps I’d best explain.

For as he dug, he came across a sandstone block or two.

I saw him get his hand-lens out to get a closer view.

He looked at them . . . he looked at me . . . and all at once I knew

He wouldn’t stop at drainage trenches. Help! What could I do?

And, sure enough, he came with spade and shovel in his hand,

And devastated even more of my once-virgin land.

He claimed it was for footings, that the whole thing was pre-planned.

Pre-planned, my foot! Such willful desecration should be banned.

He says I’ll look much nicer when he’s dug a little more.

He says his stone is ripple-marked and shows how, long before,

My ancestors had lazed around upon some wave-kissed shore.

Oh no! I bet he’ll dig until he finds a dinosaur

Well, I am Gordon’s garden, and it’s time for me to say

That up with this I will not put. That’s it. No more, okay?

I have a secret weapon: when it’s wet, it’s sticky grey;

But when his drains dry out my soil, it’s hard, rock-solid clay !

Gordon Judge

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More on the Deccan Traps

The ‘huge volumes of gases’ referred to in my article on pages 17-18 of the March issue of Stonechat have now been quantified by a group from the Open University, according to an article in the magazine Science. They conclude that the eruptions which formed the Traps released an annual flux of at least 300 - 500 million tonnes of sulphur dioxide, which would have persisted high in the ancient atmosphere for decades and been likely to have had serious effects upon Late Cretaceous environments and climate. (Worryingly, this is ‘only’ two or three times the 150 million tonnes or so said to be emitted by today’s industrial processes.)

The group examined hundreds of rock samples from the Traps and cut thin slices from them. In just a few of these slices, they found find tiny pockets of glass. They were able to measure the sulphur and chlorine ‘frozen’ in the glass, and so determine the lava’s original gas content.

‘This research,’ said the OU’s Dr. Mike Widdowson, ‘can provide vital data that we can now hand over to climate modellers as they search for ways to explain how pollution will hurt the atmosphere.’

Gordon Judge

[Main source: www3.open.ac.uk/media/fullstory.aspx?id=13340]

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Building Stones of Sussex

The April Evening Talk was given by Roger Cordiner. Following a varied career, he is now a lecturer at the University of Brighton. It is here that he met, and has became a collaborator with, Roger Birch, their mutual interest being the Geology of Sussex. It is in this capacity that he came to speak to us on the local building stones. He and Roger have been concentrating on West Sussex, making numerous weekend forays to churches and other ancient local buildings in order to examine the various stones used in their construction.

Roger pointed out that there were relatively few exposures of rock in Sussex, and thus the local buildings afford an excellent opportunity for the examination of the underlying rocks of the county. Prior to the advent of the railways and the easy transportation of heavy materials (circa 1850), much of the stone used in the construction of a building was quite local to a given area. Thus buildings serve as accessible 'exposures', although of course there can be no recourse to a good hammering! Even the use of HCl has to be a rather surreptitious operation! Furthermore, many of the quarries which were open in the past have now been filled and consequently have disappeared.

He went on to describe the geology of West Sussex: the map showing the familiar 'horseshoe' at the west of the Weald, and the associated vertical geological column. Roger then looked in detail at the geological divisions and described the rocks associated with them. For instance, from the Quaternary, Iron Pan is obtained. From the Holocene comes Travertine, whilst the Neogene holds Sarsens. In the Paleogene, there is Bognor Rock. From the Upper Cretaceous comes the Flint and Hythe Stone, and finally from the Lower Cretaceous, Horsham Stone and Ardingly Sandstone have been quarried.

He then described some of the buildings that he and Roger have visited, taking them in order of the era in which they were built, from Roman times through to the Medieval. He described various architectural styles, from the robust Saxon by way of the solid Norman to the beautiful English Perpendicular. He illustrated his talk with images of the local buildings associated with these styles and, of course, the stones listed above that were used in their construction. He gave an excellent account of our two local stones from the north of the county, the Horsham Stone and the Sussex Marble. The whole was illustrated by some superb photographs. Roger gave us a most interesting lecture, and it was particularly compelling because of the relevance of his material to our own area. Not only were the building stones familiar, but also many of the buildings themselves were well known to us. Clearly he and Roger have put in a great deal of enthusiastic research, not to mention the distance which they must have covered in the process. I was quite relieved to hear the admission from these two professional geologists that even they could not identify all the stones which they encountered, an experience all too familiar to myself! Thanks again to Roger for making the journey from Bognor to give us an excellent talk.

Peter Webster

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An Amazing Water Source.

This was seen on a label of bottled water on a recent visit to Spain:

'VICHY CATALAN starts life at the Earth's centre. It ascends slowly before finally emerging at 60degC. Along the way it generates its characteristic personality and is enriched with minerals that help you feel better.’

I wonder how it percolates through that lump of nickel-iron thereabouts.

Peter Webster

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The Urals

The Urals were named after the Uralian tribe that was once native to the northern region of Asia. They were hunter/gatherers, but lack of plentiful resources in the area forced them to relocate, spreading throughout the Asian region.

The range is aligned north/south and lies mostly just to the west of longitude 60E E, forming a natural boundary between Europe and Asia. It stretches for 1500 miles northwards from the Kirgiz Steppe to the islands of Vaygach and Novaya Zemlya in the Arctic Ocean. It is rich in minerals, including gold, platinum, coal iron, nickel and silver, and the semi-precious topaz and beryl.

Much of the range is heavily forested. In the south the tree line reaches 1400m (4600 ft.), dropping to sea level in the north. The virgin Komi Forests towards the north are recognised as a World Heritage site.

Towns and settlements are mostly small, often based on mining, but where the Trans-Siberian Railway crosses the range stands the fifth largest town in Russia, Yekaterinburg, whose latitude is about 57E N (that of Fort William). Between 1924 and 1991 the town was known as Sverdlovsk, named after a communist hero of the Russian Revolution. It now has a population of 1,300,000 and is a leading industrial and cultural centre, having numerous institutes of higher education covering forestry, mining, agriculture, law, medicine, teacher-training and scientific research. It was here that Tsar Nicholas II and his family were murdered.

Near the mountains in the south, in the province of Chelyabinsk, is the Soviet nuclear facility called the Mayak Chemical Combine. From 1948 until 1990, when the last of five reactors was shut down, the Combine contaminated the region to such an extent that it is now known as the most polluted area on Earth. The region received this title due to the Combine’s disregard for environmental and public safety; more specifically there are three incidents that stand out - intentional dumping of radioactive waste into the Techa River, an explosion at a radioactive waste storage facility in 1957, and a 1967 wind storm that deposited irradiated sediments from Lake Karachay on to the surrounding province.

Sir Roderick Murchison was commissioned by the Tsar of Russia to assess the mineral wealth of the country and as part of his journey of 14,000 miles in the summer of 1841, Murchison drew a number of cross-sections of the Urals. He took the opportunity to observe the strata from river cuttings. An extract from my book, King of Siluria, tells part of the story: Murchison’s journal had the following entry: ‘The descent of the Serebrianska [about 58E N] was one of the most memorable days of my life. The distance to be accomplished by this winding stream was seventy versts, or nearly fifty English miles. When I went to rest, the bed of the river was almost quite dry, with not water enough to drown a rat, and yet we were to effect the miracle of floating down in a six-oared boat. When I awoke a furious stream was rushing down, and the natives were beginning to get canoes. The good commandant [M. Moskvin], having the Imperial order that I was to descend by water, had let off an upper lake [the Zavod], and thus made a river in a fine dry sunny day!

‘The waters having been let off for us, and the river bed filled, we effected our embarkation amid three cheers. The river was muddy, and had rocks hidden, with very sharp curves of the stream. With a hundred groundings and stoppages, we got tired of our big boat of honour, and took to the canoes. These answered well for a while, but trusting to shoot through some stakes and nets (myself on my back at the head of the canoe), we (i.e. de Verneuil and myself) were capsized in a strong current. I saved my notebook (see the stains), but my cloak, bag, pipe, etc., went floating down. A curious scene followed, after we had scrambled out to the shore. The other canoe shot by and picked up our floating apparatus. Fortunately this letting off the waters had brought down some natives to catch fish, and they had a fire, by which we dried ourselves, whilst their large wolf-dogs lay around us. When we re-embarked, we shot several ducks (Merjanier), and here and there found limestones and shales striking to the N.N.W. Some of the limestones were charged with Devonian fossils.

‘After this, evening began to fall. Saddles, anticlinals and synclinals arose in magnificent masses on the rocky banks, but our boat-bottom was soon knocked to pieces by grounding at least a hundred times, and whisking round as in a waltz at each shock. It now filled so rapidly that we had just time to escape. We had then a fine evening scene. We landed on shingle, and got into the forest, not having seen a house or hut for fifty miles. The dense wildness of the scene, the jungle and intricacy of a Russian forest, can never be forgotten. We had to cross fallen trees and branches, and to force through underwood up to our necks.

‘After our various night evolutions, sometimes by land and sometimes by water, we finally reached our “derevna” (Ust Serebrianska) at two a.m., wet up to the middle, by walking through moist jungle and meadow. Our men were very amphibia, and required no food. They had been half the day in that stream, pulling, hauling, shoving, and shouting, and never eating or drinking. We had to awake the chief peasant’s family, and were soon in a fine hot room, with children sleeping all about.’

                                                                                  John Morton

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Dinosaur dam

(A short note in New Scientist, followed by a bit of Googling, has produced this.)

In the Heilongjiang Province of north-east China is Dinosaur Mountain. According to a recent report (22 October 2007) in the China Daily, Dinosaur Mountain ‘sits right on the river that forms the boundary between China and Russia’ - the Heilongjiang River. The mountain used to be called Mountain of Dinosaur Bones because thousands of dinosaur bones have been unearthed from it in the past. Some thirteen skeletons have been assembled from these remains and are now exhibited in several museums throughout China.

But Dinosaur Mountain is believed still to hold enough fossil bones to put together another hundred or more dinosaur skeletons. Every summer, rising waters and strong currents erode parts of the mountain, leaving dinosaur fossils exposed. ‘Many fossils have been washed away in the past,’ said Li Jinshan, Vice Director of Jiayin Dinosaur National Geologic Park Administrative Bureau. (An opportunity for geologists downstream?)

So three years ago the Land and Resources Department of Heilongjiang Province ordered that a 1450 m earth dam, 5.5 metres high and 10 metres wide, be built on the Chinese bank of the river, to stop the fossils from being washed away. For three years workers have contended with rising waters and strong currents in summer and long cold winters at high altitude, but the job is now completed, says the report.

                                                                                    Gordon Judge

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 Geological Anniversaries and `Local Heroes'

Dr Frederick Dixon (1799-1849) was the youngest of three sons of Rector of Sullington, a downland parish. He qualified as doctor at St Bartholomew's Hospital, married, honeymooned round the Mediterranean and then came to live in Worthing in 1827. He had a lifelong fervent interest in fossils of the Chalk and Early Tertiaries of West Sussex. He was a friend of Gideon Mantell, Peter John Martin, etc, and, in particular, of Richard Owen. He was elected FGS (1840) supported by Mantell, Lyell and Murchison and died suddenly in September 1849, leaving his magnificent opus on Geology of Sussex unfinished. This was brought to publication by Richard Owen in Dec 1850 and contains 44 superb plates of fossils: it is still a standard work of reference. He spent 20 years amassing a significant fossil collection (4500 specimens), which his widow sold to the BM. The collection was dispersed but its catalogue survives. His work is second only to that of Mantell in its geological significance in Sussex. Dr Dixon was well-known in geological circles in the 1830s/40s, decades of great significance in the history of geology, and was influential in many of the important debates in those times. The West Sussex Geological Society will celebrate Dixon in three events:1) A two-week Exhibition in the foyer of Worthing Library about the Life, Times and Work of Dr Dixon either side of:

2) A Public Evening Lecture in Worthing Library Lecture Theatre on Friday 4 April on Frederick Dixon and the Geology of Sussex, by Anthony Brook

3) A Field Trip on Saturday 5 April to The Trundle and Bracklesham Bay, led by David Bone (who has been researching this area for 35 years) on a day with a mid-afternoon low tide, to view Dixon's field area, collect similar fossils and evaluate his pioneering contributions, alongside work by 20th-century researchers such as Martin Venables and the Tertiary Research Group.

For further details contact: Tony Brook e-mail: Anthony.brook27@btinternet.com

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 Libya’s Great Man-made River

It’s a geological fact, a geographical mis-match and an expensive logistical challenge: Libya has large reserves of fresh water beneath its Saharan deserts, far away from the large urban populations along its coastline. But in October 1983, the Great Man-made River Authority was created to respond to the challenge.Work started in Sarir in 1984. Pipeline water had reached Benghazi from the eastern desert by 1993, and Tripoli, from the western well-fields, by September 1996. In March 2006, Phase III, which links the two earlier Phases, was ‘still under construction’. In September 2007, the water had reached Gharyan, 50 km south of Tripoli. The final two Phases involve the extension of the distribution network together with the construction of a pipeline linking the Ajdabiya reservoir to Tobruk, and finally the connection at Sirt of the eastern and western systems into a single network.Articles on the internet about the project are full of big numbers (not always mutually consistent): total costs are in the region of $30 billion; two special factories, built to manufacture the pre-stressed concrete pipe sections, used some 2500 tonnes of cement per day; each pipe section is 4 m in diameter, 7.5 m long and weighs up to 86 tonnes; there are 1300 wells, and about 5000 km of pipeline laid in trenches about 7 m deep. When complete, the plan is that some 155,000 hectares of land will be irrigated by up to 6.5 million cubic metres of fresh water a day to produce 270,000 tons of crops, three times as much fodder and an ‘abundance’ of fruit and vegetables. The Lonely Planet’s 2002 guide to Libya notes that the project aimed to set up 37,000 model farms and increase wheat production in the north by 180,000 hectares. The water lies deep underground in four major basins. In total, they are said to hold over 35,000 cubic kilometres of ‘fossil’ water.The sedimentary basins from which the water is to be drawn were formed during the tectonic plate movements at the end of the Mesozoic which created the Red Sea and Morocco’s Atlas Mountains. The water now trapped in this porous Nubian Sandstone has been there since North Africa had a temperate climate between 40,000 and 10,000 years ago.Although tectonic activity has quietened, there are still rumbles of the geo-political sort. Bizarrely, in 1997 the CIA was apparently convinced that the pipelines were hiding a vast infrastructure of secret military tunnels and underground weapons storage facilities. Perhaps more significantly, some hydrologists believe that the rapid depletion of the aquifers could lead to seepage from the Nile; and if the Nile is threatened, says an Egyptian journalist, Egyptian intelligence services are ‘not averse to invading’. Geologists, meanwhile, fear that seepage, combined with freezing desert temperatures, could cause trapped frozen water to crack sub-strata, and damage the desert. Lonely Planet quotes ‘evidence to suggest that the GMMR has begun to lower the ground-water table in north-western Libya, with potentially disastrous consequences for agriculture’. Tuareg tribes have reported drier wells, though there’s no proven link to the GMMR. And in 2002, a project manager reported that some pipes were so corroded that the River was shut down at least three times.

Libyan leader Colonel Muammar al-Qaddafi has described it as the ‘eighth wonder of the world’. For now, perhaps. But this is a project with a limited life. The basins are not expected to refill. If you divide their huge volume by the daily flow rate given above, you get a lifespan of 14,752 years. But that must be too simple a calculation: sceptical experts reckon the water will flow for only between 15 and 50 years. Perhaps coincidentally, 50 years is also the reported design life of the concrete pipe sections.

Gordon Judge

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Lisbon, 1755

The Reverend Charles Davy knew what an earthquake felt like. He had endured a fairly mild one in Madeira some six or seven years ago. Today, November 1st, 1755, as he sat writing after breakfast, he was reminded of his earlier experience. In his first-floor apartment among the narrow streets of Lisbon, his writing table trembled gently and his papers moved as if blown by the wind. But there was no wind: the sun shone brightly in a cloudless sky.

Then the house itself shook. The Reverend quickly rejected any idea that passing coaches must be rumbling past in the street below, in favour of his Madeiran memory. The hollow thundering, ‘a strange frightful kind of noise underground’, lasted less than a minute but was enough to convince him that it was the sound of an imminent earthquake. Abandoning his pen, he hesitated, wondering whether, like Madeira, it might not be too bad –– would it be it safer to stay in the house or risk injury in the streets? But a mighty crash, ‘’as if every edifice in the city had tumbled down at once’, soon resolved his quandary.

The house shook, and its upper stories collapsed. In his first-floor room, the walls rocked and fell away in several places; large stones and roof timbers fell all about him; and the sky took on ‘an Egyptian darkness’. Choking with the dust, Charles hurried out of the remains of his house and through the streets towards the River Tagus. He dodged collapsing buildings and clambered over the ruins of St. Paul’s Church to arrive at the riverside among ‘a prodigious concourse of people of both sexes and all ranks and conditions’. He noted priests, purple-robed church dignitaries, and ‘ladies half dressed and some without shoes’ among the crowds who were now on their knees, praying for mercy.

A second shock then completed the destruction of the remaining buildings, including a parish church on St. Catherine’s Hill, to where another crowd had fled. Many were killed on the spot, others mortally wounded. Though less violent than the first, this second shock nearly toppled Rev. Davy from his knees. Then came the cry: ‘The sea is coming in, we shall all be lost!’ The river, some four miles broad at that point, was ‘heaving and swelling in the most unaccountable manner’, and on this swell appeared a huge wave, ‘rising as it were like a mountain . . . foaming and roaring’. The whole company ran for their lives: many were swept away; others who had reached higher ground were up to their chests in water; and our hero survived by clinging to a large beam until the surge had passed.

Clearly, the Davy brain reckoned, the idea that the river bank was safer than the city was now questionable, so with dripping clothes, he retreated to where St. Paul’s had been. Here, he watched ships being tossed about on the violent waters below ‘as if in a violent storm’, yet without any wind; and he witnessed ‘the fine new quay, built of marble, at an immense expense . . . entirely swallowed up, with all the people on it who had fled thither for safety’.

In his account, the Reverend Davy records another incident reported to him by a friend on the opposite side of the Tagus. No sooner had the river surge passed his friend’s house, than ‘immediately a great number of small fissures appeared in several contiguous pieces of ground, from whence they spouted out, like a jet stream, a large quantity of fine white sand to a prodigious height’. People around him had reported sulphurous smells, though he had not noticed this himself.

Then came the third shock. Again the sea rushed in, reaching, even at his now more elevated position, up to his knees. The surge retreated rapidly, but then repeated its actions several times in succession. Davy notes that the devastation would have been greater if ‘the force of the waves had not been somewhat broken by the winding of the bay’.

So even on this higher ground he was not safe. Where could he go now? Of course –– why hadn’t he thought of it before? What building in the city is built low and very, very strong? Why, the Mint, of course! When he arrived at its entrance he found it guarded only by the eighteen-year-old commanding officer of the guard, remaining loyally at his post after all his soldiers had fled. Davy was most impressed with the young man’s courage and steadfastness, and told him so; but with the tremors continuing, and the houses opposite the Mint tottering alarmingly, the two men ‘retired inward to a hillock of stones and rubbish’.

When darkness came, fires which had broken out in the city were so bright that one could see to read. They continued unabated for six days. Davy suspected they had been started, not by the earthquake, but by the combination three causes: burning lamps and wax tapers that decorated every church for All Saints’ Day setting fire to curtains and timber when the buildings fell; the houses’ own kitchen fires; and arson by ‘hardened villains’ released by the destruction of their prison.

Ever interested in detail, the Reverend Davy noted that ‘with regard to the buildings, it was observed that the solidest  in general fell the first’. He reckoned that ‘the whole number of persons that perished, including those who were burned or afterwards crushed to death whilst digging in the ruins, is supposed, on the lowest calculation, to amount to more than sixty thousand’.

Gordon Judge

[Based on a modernised version of Rev. Davy’s account given in the Internet Modern History Sourcebook, on-line at www.fordham.edu/halsall/mod/1755lisbonquake.html.]

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Postscript: Lisbon and Atlantis

A paper in the European Review by M.-A. Gutscher, of the Institut Universitaire Europeen de la Mer, last year suggests that the 1755 Lisbon earthquake was of magnitude 8.5––9. Although the fault that generated it has not been identified, recent data from the Gulf of Cadiz suggests an active east-dipping subduction zone beneath Gibraltar. Given that eleven out of the twelve strongest earthquakes in the past 100 years have happened along ‘subduction zone megathrusts’ –– including the December 2004 and March 2005 Sumatra earthquakes –– the author declares that ‘it appears likely that the 1755 earthquake and tsunami were generated in a similar fashion, along the shallow east-dipping subduction fault plane’.

Enthusiastically, the author goes on to interpret other records as possible evidence for ‘great earthquakes off south-west Iberia every 1500––2000 years’. What’s more, Roman records from Cadiz of just such an event around 200 BC are apparently ‘supported by tsunami deposits’. Now at academic fever pitch, the author notes that, according to Plato, it was ‘strong earthquakes and floods’ that destroyed Atlantis some 11,600 years ago.

With steam now erupting from an overheated brain, the author finally makes the crucial link. ‘A 1 m thick turbidite deposit, containing coarse-grained sediments from underwater avalanches, has been dated at 12,000 BP and may correspond to the destructive earthquake and tsunami described by Plato. The effects on a paleo-island (Spartel) in the Straits of Gibraltar would have been devastating, if inhabited, and may have formed the basis for the Atlantis legend.’

                                                                                Gordon Judge

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