All the above were classes of peasants dependant on the Lord of the Manor. The Villein was the highest class of peasant often holding between 30 and 100 acres. Then there was the Bordar who was a middle class peasant. The lowest class of peasant cultivators at the time of Domesday was the Cottar.
Bovate/ Carucate/ Acre
A carucate is a measurement of an area of land. The measurement varied
from region to region and was often approximated to 120 acres. A Bovate
was an eigth of a carucate and hence was approximated to 15 acres. An Acre
was traditionally taken as a days ploughing for one plough team. It now
equates to 220 x 22 yards. 20 were reckoned to be the average to support
a family.
Originally this title was given to towns where veteran soldiers could retire after being discharged from the legion. Later the title lost its military significance and became the highest ranking civilian town in Roman Times ranking higher than a municipium (a self governing town).
Imagine the scenario where part of field contained a wall. The wall has collapsed and all that is left is a few inches of stone below the surface of the ground. These stones will affect the drainage of the soil immediately above it and (if the stone is limestone) will affect the fertility of the soil above it. Thus when crops are grown in the field, the plant immediately above the wall will grow more slowly than elsewhere in the field. Thus although the wall cannot be seen above the ground, on a late clear evening when the sun is at a low angle, the difference in length of the crops due to the difference in fertility of the soil will show as a long shadow indicating where the wall is. This principle applies to walls, pits and virtually any large man made objects.
A Terminal Moraine is a ridge of hills that are formed at the edge of a glacier during the ice age. During the summers, the warm temperature makes the ice retreat. During the winters the cold temperature makes the ice advances. As it retreats and advances it 'carries' boulders and earth to the edge of the glacier and deposits them. These build up over the years to become small hills. (This was how it was explained to me at school but like the explanation of evolution, you need a top notch imagination to appreciate the mechanism and the time scales.)
A suitable analogy is imagining the effect of the huge glacier being
like a giant iron. As the glacier advances and retreats, the sheer weight
of the glacier acts like a giant iron, smoothing the ground underneath.
Where the huge iron consistently stops at a point, then the ensuing 'crease'
is the position of the Terminal Moraine