514 J. Lamplugh — Marine Shells in Boulder-clay. 



Divisions adopted by Messrs. "Wood 

 and Rome, Quart. Journ. Geol. 

 Soc. vol. xxiv. p. 147 (omitting 

 the freshwater marls). 



Diagrammatic section of the Drift 

 at Bridlington, proposed by J. 

 Lamplugh. 



Gravel, principally of Chalk. 



Sands and Gravels. 



Hessle Boulder Clay. 



Hassle Sand and Gravel. 



Purple Boulder Clay, with Sands 

 and Gravels, inclusive of the 

 Bridlington Crag. 



Sands, with Gravel. 



Chalky or Basement Clay. 



Chalk. 



Chalky Gravel. 



Sand, "Warp, and Gravel. 



Hessle Series absent from the 

 immediate neighbourhood, 

 unless represented by the 

 lower 



Gravel. 



Purple Boulder Clay, with Sands 

 and Gravels. 



Locally a bed of laminated Clay. 



Bridlington Crag Deposit, consis- 

 ting of Sands and Sandy Clays 

 lying on and mingled with 

 the Basement Clay. 



Chalk. 



ported in an immense frozen mass, whicli is rendered highly 

 improbable by the fact that most of the shells are of deep-water 

 species, and also by the position of the shells, with closed valves, and 

 even, as was witnessed by Mr. Bed well (see subsequent note), in 

 their natural position as when alive. 



The only probable solution of this problem which has presented itself 

 to me, is to suppose that during the earlier periods of the Glacial epoch, 

 a sandy sea-bottom was formed, probably founded on the already 

 partially accumulated * Basement ' clay, on which the shells in 

 question lived and died ; and that this bottom, during a period of 

 extreme cold, was ploughed up and destroyed by floating-ice (coming 

 mainly from the north), which, melting, incorporated the sand and 

 broken shells with its own burden, consisting in part of masses 

 gathered on its southward journey. This disturbing process would 

 doubtless be often repeated, thus giving rise to the sandy clays, 

 which have already been described as being the stronghold of the 

 shell-fragments, and as forming part of the ' Basement ' clay. 



Under this view, the Bridlington and Dimlington ' Crag ' beds 



