86 SECTIONAL ADDRESSES 



the existence of even older and cruder forms. I must leave the debatable 

 question with the picture of this very primitive man driven from his hunting- 

 grounds by the advance of the first great ice-sheet, and only note in passing 

 that the remains of Piltdown Man, although found in a Pleistocene gravel, 

 are not datable with exactness, being accompanied by derived bones of 

 Pliocene animals and flakes which, if referable to any particular period, 

 must be attributed to the Chellian or even an earlier industry. 



The retreat of the Scandinavian ice appears to have been followed by 

 a long interval, during the earlier stages of which the area of East Anglia 

 was a shallow sea or lake, inhabited by a cold moUuscan fauna. Into 

 its waters were discharged large quantities of sand and gravel, released 

 from the waning ice-sheet. During the later stages of retreat the area 

 was uplifted and the East Anglian valley-systems were carved out of the 

 deposits of brickearth, gravel and sand. Little evidence is forthcoming 

 regarding conditions in Yorkshire and northern England during this 

 First Interglacial interval, but in the Midlands and Thames Valley certain 

 high-level plateau-gravels may have originated as outwashes from the 

 ice, and some of the oldest river-gravels may have been the products 

 of the subsequent erosion and aggradation of the pre-existing valleys. 

 By inference, Chellian Man advanced into such parts of the British area 

 as were available to him, for, although we find no ' floors ' of unabraded 

 tools of the Chellian industry, derived and abraded implements are not 

 infrequent in later deposits. 



The First Interglacial interval was brought to a close by the develop- 

 ment of ' home-grown ' ice -caps on the Scottish mountains, the Lake 

 District and the Pennines. The chief glaciers thus produced appear 

 to have developed and flowed east of the Pennines, possibly because 

 of the cooling effects of the proximity of the Scandinavian ice, for the 

 manner in which the earlier Cheviot ice and the Purple Boulder Clay 

 ice hug the low ground to the East Coast, taking a southward course 

 parallel to it, suggests that most of the North Sea was still filled with ice. 

 The Lower Purple Boulder Clay ice does not appear to have risen 

 sufficiently high to override the Lincolnshire Wolds westwards. On the 

 west of this escarpment the Great Chalky Boulder Clay ice, augmented 

 by the sheets which had flowed down the Yorkshire Plain (together 

 with Lake District ice which had come over Stainmore), travelled up the 

 valley of the Trent and down that of the Witham, fanning out across the 

 low ground of the eastern Midlands. Part of the sheet, which crossed 

 the Fen district, spread eastwards and southwards over East Anglia, 

 reaching to Finchley in North London. Other portions of the ice- 

 sheet spread south-westwards over the central Midlands and may have 

 given rise to the most far-flung example we know, the Moreton Boulder 

 Clay of the Cotswolds. The ice which had descended eastwards from 

 the Pennines seems only to have been sufficiently powerful to travel 

 southwards side by side with the Great Chalky Boulder Clay ice, and 

 thus to have been elbowed into the Avon Valley. At the same time, 

 ice appears to have advanced from the North Sea in a south-easterly to 

 southerly direction on to the Norfolk Coast, thereby influencing the 

 course of the Chalky-Neocomian and Chalky-Jurassic glaciers. 



Over the greater part of England this Second Glacial Episode was that 



