of our DUtrict during Historic Times. 279 



have rendered the natural drainage very imperfect, and probably 

 the rainfall would be much greater than at present. 



With regard to the fauna, the animals would be much the 

 same as at present, the beaver, the wolf, and the wild boar being 

 probable additions, while most probably the red deer existed in 

 considerable numbers. 



The chief factors in the formation of the soil, as we now see 

 it, have been (1) the clearance of wood and cultivation of the soil 

 by man, (2) subaerial denudation and dissolution of the chalk by 

 rainfall, (3) the action of earthworms. Before entering into 

 historical matters, it will, perhaps, be as well to treat of the two 

 latter factors. I do not think that subaerial denudation can have 

 had much influence in our district during the comparatively 

 short period we are considering. Until the slopes of the hills 

 were cultivated their natural clothmg of turf would protect them 

 from the disintegrating influence of the frost, and in most cases 

 from rain-washing, though on the clay and gravel soUs this may 

 well have had a greater influence. The amount of chalk dissolved 

 by the carbonic acid in rain-water has been calculated at 9-lOOths 

 of an inch per century, and even if we suppose the rainfall to 

 have been twice as great as at present, this would only amount 

 to 2-7 in. in 2000 years. 



In regard to earthworms, Darwin's well-known work on these 

 animals, largely based on observations in a district adjoining and 

 similar to ours, shows that they have played a very important 

 part. One of his experiments showed that a layer of chalk 

 spread on a meadow was buried to the depth of 7 in. in 29 years. 

 He states that over 10 tons of dry earth annually passes through 

 their bodies, and is brought to the surface on each acre of land, 

 so that the whole superficial bed of vegetable mould passes 

 through their bodies in the course of every few years. Their 

 habit of dragging leaves into their burrows adds to the soil, and 

 by the acids formed by their decay disintegrates the lower beds. 

 The castings ejected are washed by the rain, blown by the wind, 

 or spread by animals, until every irregularity is filled up. The 

 well-known ledges on the slopes of the hills, generally called 

 sheep-walks, are in all probabihty due to the worm-castings 

 rolling down until stopped by some irregularity of the surface, 

 plants, or grass. If these are carefuUy examined they will be 

 found to taper oflf at each end to other ridges, more like long 

 scales than definite paths. Although these tracks are used by 

 sheep, Professor Henslow and Darwin do not consider that they 

 are formed by them. 



But the most important influence on the aspect of the land, as 

 we now see it, has been man and his domestic animals. The 

 early races of prehistoric man, being solely hunters and not 

 cultivating the soil, would change it but little, but later races 



