318 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1917. 



erratics might occasionally survive from the period of greatest cold, 

 the molluscan fauna of the beach would be that existing when it was 

 finally elevated. On these grounds the raised beaches and associated 

 deposits of south and west England can be tabulated and correlated 

 as follows : 



SOUTH AND WEST ENGLAND. EAST ENGLAND. 



1. Bowlder clay of Pencoed and scat- North Sea drift. Chalky bowlder clay, 

 tered erratics. 



2. Raised beach of Chichester and the Marine gravels of March and Holder- 



west, ness. 130-foot terrace of Thames. 



3. Estuarine series of Selsey. Marine 100-foot terrace of Thames. Temper- 



and seolian sands of Devon with ate beds of Hoxne. 

 temperate fauna. Chelles fauna 

 of Caves. 



4. Raised beach of Selsey and Brigh- Middle terrace of Thames. " Warp and 



ton. " Head." Gravelly bowlder trail." Arctic beds of Bonder's End 

 clay of Gower. and Hoxne. Hessle bowlder clay. 



The Upper Head of Gower may belong to period No. 4 or may be 

 contemporary with the lower terrace of the Thames. 



There is no evidence that the south of England arid south Wales 

 have ever been below their present level in postglacial (or post 

 "■ head ") times, if we except the faint suggestions put forward for 

 South Devon by Hunt and Rogers (88), but there is abundant evi- 

 dence that the land stood at least 80 feet higher in the " submerged 

 forest " period. These forests are all neolithic, but seem to approxi- 

 mately fill that period, since both early and late neolithic implement 

 types are represented. The flora is poor, and composed of widespread 

 species, and so gives no definite evidence as to climate. C. Eeid con- 

 siders the submergence to have been fairly rapid, and to have termi- 

 nated about 3,500 years ago; it has left a tradition that St. Michael's 

 Mount once rose from the midst of a forest. 



NORTHWEST ENGLAND. 



In northwest England we again find a tripartite division of the 

 glacial deposits. At the base is a hard, stony till with marine shells, 

 overlain in many places by deposits with erratics and occasionally sea 

 shells, but only such as could have been derived from the neighbor- 

 ing bowlder clay ; they include the well-known deposits of Moel Tre- 

 faen and. Macclesfield. At lower levels these sands and gravels are 

 overlain by second bowlder clay. No evidence has yet been brought 

 forward of contemporary fossils in the sands and gravels, and there 

 is no evidence that they represent more than an oscillation of the ice 

 edge. The lower bowlder clay is in general gray, and gives no evi- 

 dence of a much greater age than the upper clay. 



