66 THE PRINCIPLES OF 



it actually does form the soil, gives land of retentive 

 character, but, as I have had occasion to point out previously, 

 the general stiffness of the London clay is interrupted by 

 the Bagshot series, the Thanet sands, and the Bracklesham 

 beds, which predominate largely in the neighbourhood of 

 Windsor and Epsom, and pass onwards towards Aldershot, 

 giving in that part of the field, soils of a light and poor 

 character. 



The valley of the Thames also, with its large accumulation 

 of alluvial soils, in the neighbourhood of London, modifies and 

 alters the general character of the soil, so that in many cases 

 within this area a light soil occurs, and in other cases an 

 unusually fertile soil. Where the London clay comes into 

 close contact with the upper chalk, which it does around its 

 entire margin, a favourable change in the general character 

 of the soil is noticeable. The drainage is improved by reason 

 of the underlying chalk sub-soil, and the admixture of a large 

 number of flint stones with the clay tends to open it up and 

 make it more fit for ordinary agricultural operations. 



Another large area covered by the soils of the London clay 

 may be described as follows : It also is triangular in shape, 

 and upon reference to a geological map, we shall find the 

 apex of the triangle at Salisbury, and the boundary stretching 

 in a south-easterly direction from Salisbury to Worthing, and 

 in a south-westerly direction from Salisbury to Wey mouth ; 

 the base of that triangle being the sea-coast passing the Isle 

 of Wight, and extending from Worthing to Weymouth. 



Although the London clay proper yields strong lands, yet 

 by far the greatest area is composed of light-toppod, sandy, 

 gravelly soils, frequently of very poor character indeed, in- 

 cluding the whole of the large district known as the New 

 Forest. This interesting tract is of such poor character that 

 it is difficult to believe the truth of those old stories which 

 tell us that the Conqueror devastated a fertile country, and 



