314 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1917. 



eastern types. In the coombe rock implements of Acheulian-Mous- 

 terian type have been found near Brighton. West of Brighton there 

 is a section at Portslade showing typical "head" underlain by sand 

 and clay with Mytilus, Litorina^ and pebbles, some igneous. 



At the bottom of the sand was found a piece of hard purple quart- 

 zite, 4 inches long, quite angular, and broken into two pieces in situ. 

 The marine beds here are about 10 feet lower than east of Brighton, 

 either because they were formed farther seaward or because the 

 submergence at this period diminished westward. 



At the base, resting on and squeezed into Bracklesham clays, are 

 the Selsey erratics, overlain by marine and estuarine beds with tem- 

 perate (southern) Mollusca and redeposited erratics. The Mollusca 

 include Corbicula fluminalis and Bithynia tentaculata. These beds 

 are overlain by the raised beach, resembling that of Brighton, but at 

 a lower level, and this again by "head," here a loam. 



Farther west the raised beach and head are well seen at Selsey Bill 

 and near Chichester, but the phenomena here are more complicated. 

 They have been described by C. Eeid in several papers (82). Reid 

 correlates these temperate deposits with Corbicula fluminalis with 

 the Thames gravels with the same shell, the Clacton raised beach, 

 with C. fluminalis and Paludina diluviana, and the gravels of March 

 and Holderness. He remarks: 



Though the land and fresh-wator species show little change of climate be- 

 tween south and east, there exists a marked difference in the marine Mollusca. 

 In Sussex the marine fossils seem to indicate a sea warmer than the air, 

 while in the eastern counties the air was apparently warmer than the sea. 



The Selsey Peninsula is backed by a line of old cliffs which cut 

 obliquely across the chalk and Eocene, and associated with this in 

 places are remains of the corresponding marine sands and gravels, 

 at a level of about 100 to 105 feet at Tortington Common, 120 feet 

 near Arundel, 90 feet near Boxgrove, 130 feet at Waterbeach, where 

 it contains large blocks of Pholas-hored and worm-eaten chalk, and 

 occasional small shells. Here it is overlain by coombe rock, chalky 

 paste with angular flints, which passes southward into loam. 



North of the Chalk Downs no trace of these marine deposits has 

 been found, so that the submergence must be older than the erosion 

 of the valleys. Further, as the marine sands and shingle can not be 

 related to the much lower beach shingle at Selsey and Brighton, they 

 must correspond to an earlier submergence of 100 feet, which may 

 be related to the submergence of 100 feet (130-foot terrace) in the 

 Thames Valley, immediately succeeding the first glaciation. 



The large bowlders of the Selsey foreshore must have been ice- 

 carried, and evidently indicate a considerable submergence, for the 

 ice which floated a 2-ton bowlder must have been thick, so that it is 

 probably not far different in age from the raised beach of Chichester. 



