308 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1917. 



6. GREAT BRITAIN. 



In applying to the glacial deposits of Britain, the classification 

 worked out for north Europe, we find that even in eastern England, 

 where deposits of two glaciations occur associated, a direct proof of 

 a difference in age is more difficult. But the bowlder clays which on 

 stratigraphical and paleontological grounds are classified as belong- 

 ing to the first glaciation of England are vastly more weathered and 

 eroded than those of less extent which are classified as belonging to 

 the second glaciation. Moreover, almost without exception every 

 locality in England where older paleolithic implements have been 

 found lies outside the limits of this younger bowlder clay. These 

 implements are associated with the well-known warm-temperate 

 fauna of Chelles, which is incompatible with a climate appreciably 

 colder than the present ; they are indisputably younger than the older 

 bowlder clay and older than the younger bowlder clay, and on these 

 grounds alone we should be justified in inferring two glacial periods 

 in England separated by a temperate interglacial period. 



The starting point must be S. V. Wood's division of the East 

 Anglian drifts into contorted drift, middle sands and gravels, and 

 chalky bowlder clay. The lower tills of Cromer and the arctic 

 fresh- water bed can not be separated from the contorted drift. At 

 Cromer the middle sands contain Nassa reticosa, Anomia, Denfalium^ 

 and Scalaria Groenlandica (65). The same bed at Yarmouth con- 

 tains a much larger fauna of mollusks and ostracods, but still boreal 

 and arctic (06). They form no evidence for an interglacial period. 



Northwest of Cromer isolated hills rising above the Fens show 

 marine sands and gravels; these contain a northern but not arctic 

 molluscan fauna with in places Corhicvla ftwininalis, as at March. 

 They are associated with old valley gravels, containing Pleistocene 

 mammalia {Hippopotamus^ Elephas antiquus, E. prinilgenius, 

 Rhinoceros tichorhinus, and Felis spelaea) ; this resembles the fauna 

 of the older interglacial of north Germany. The beds also contain 

 flint implements, Chellean or Acheulian type; they rest on chalky 

 bowlder clay. 



The next clear sequence is that of the coast of Holderness (68), 

 where again there are four bowlder clays, the upper two separated 

 by stratified gravels. The uppermost division is the Hessle bowlder 

 clay, quite indistinguishable lithologically from the lower clays, but 

 with smaller bowlders and no shell fragments. S. V. Wood's sec- 

 tion was at Hessle, where it overlies the mammaliferous gravel, but 

 overlaps it on to the chalk. The relations of the Hessle clay can 

 be seen more satisfactorily at Kelsey Hill, in Lincolnshire, where 

 bowlder clay 13 feet thick, but very much weathered, overlies the 

 marine gravel, which here, opposite the Humber gap, contains great 



