THE GEOLOGICAL RECORD 207 



Pleistocene Deposits are found in many parts of the country. 

 They are usually unconsolidated, and have mostly been formed 

 on land. Their most striking member is the boulder-clay 

 (Figs. 22 and 23), formed by the action of glaciers and ice sheets, 

 the climate having been sufficiently cold to allow these to 

 extend over the whole country north of the Thames. Fossils 

 are not common, but they include arctic shells, and mammalia 

 which could live in a cold climate, such as the woolly elephant 

 or mammoth and the woolly rhinoceros. The vegetation also 

 was sparse and of an arctic character, including the dwarf birch 

 and willow. 



After the Glacial Epoch the climate gradually ameliorated, 

 and such materials as raised beaches, cave-earths, river gravels 

 and alluvia, blown sands, peat, lake, and fen-deposits were laid 

 down. The most important fossils are the remains of man and 

 his contemporaries, the former in the shape of stone weapons 

 made at first of flint rudely chipped into shape. Eventually 

 man learned to finish stone implements by grinding them to an 

 edge, later still to work in bronze, and at last in iron. 



