

CHAP. XIII.] PLEISTOCENE EPOCH. 267 



very striking and suggestive. From Hunstanton and 

 Burnhani to the latitude of Bury St. Edmunds, the whole 

 country presents the appearance of having been planed 

 down by some powerful agency. No part of the surface 

 rises above the level of 270 feet, and the greater portion is 

 much lower. The slopes of the Chalk hills do not present 

 the bold features which they possess in Cambridgeshire, 

 and there is no continuous ridge which could be dignified 

 with the name of an escarpment, that feature only really 

 commencing with the hills south-east of Newmarket. The 

 height of these latter hills is nearly 400 feet, and south of 

 the Cam Valley the escarpment rises to more than 500 

 feet. It is true that the Boulder-clay climbs these slopes, 

 but it dies out on the heights above Hitchin, at a level of 

 about 550 feet, giving place to loams which have been 

 formed from the material of the clays and sands of the 

 Reading Beds, and are often merely reconstructed plastic 

 clay, just as the chalky clay is often only reconstructed 

 chalk. At lower levels, however, the typical chalky 

 Boulder-clay continues much farther south, extending 

 through Herts and into Middlesex as far as Finchley, and 

 on the western side of the Chiltern Hills to the neighbour- 

 hood of Aylesbury and Buckingham. 



How far to the westward this clay originally extended we 

 do not yet know, but no trace of it has been found beyond the 

 limits of a line drawn through the central parts of Oxford- 

 shire, Warwickshire, and Staffordshire. Northward the 

 clay is known to extend through the counties of Notting- 

 ham, Rutland, and Lincoln, and it probably reaches into 

 the Vale of York. 



In these last counties, as well as in Staffordshire, Derby- 

 shire, Cheshire, and Lancashire, there is another very 

 different group of deposits. These consist of reddish or 

 chocolate-brown Boulder-clays, with interstratified beds of 

 sand, loam, and gravel, the latter containing in some 



