22 8. V. Woodjun. — American and British Surface- Oeology. 



the Hessle clay and the Upper Boulder-clay of the North-western 

 counties of England ; and taking into consideration the latitude and 

 degree of glaciation in the various parts of Britain over which the 

 formations of the period of minor glaciation which I have in the 

 foregoing description supposed to be synchronous occur, there 

 appears to be a general correspondence between them both in 

 climatal conditions, and in the recent character of the moUusca 

 wherever these latter are present. 



Mr. Tiddeman also, whose attention has been chiefly directed to 

 the Lancashire mountain district, has in a paper read before the 

 Anthropological Institute on the 22nd May, 1877 (Nature, vol. xvi. 

 p. 70), expressed in precise terms his belief in there having been 

 a period of major glaciation, of which the evidences are most ap- 

 parent in the central or less northern parts of our island, and a 

 period of minor glaciation whose evidences are confined to those 

 northern parts ; while Mr. J. Geikie in the second edition of his 

 '•' Great Ice Age " takes a similar view of the synchronism of the 

 Hessle beds, the beds of the north-west, and of the gravels of the 

 Highland valleys, to that which I have done ; and I am gratified to 

 be able so far to agree with all these gentlemen. 



To this same time or nearly so, and long after the warmer waters 

 of the Biscayan and Lusitanian coasts had at the close of the major 

 glaciation been separated from the colder waters of the North Sea by 

 the conversion of a portion of that sea into land, I have referred the 

 gravel with great erratics of the Sussex coast which overlies the 

 marine mud-bed of Selsea, first described by Mr. Godwin-Austen 

 (whose list of shells was largely added to by Mr. A. Bell),' containing 

 semifossilized mollusca of southern facies all still living in South 

 British and Lusitanian waters, but among which are included some 

 that do not now range so far north as the British Channel. The 

 erratics of the gravel and clay which overlie this formation are 

 referred by Mr. Godwin-Austen to the action of coast-ice drifting 

 from the French side of the Channel.' 



We have thus, according to my apprehension of the case, a con- 

 vergence of evidence to show that a well-marked interval of minor 

 glaciation following upon the occupation of the sea-bottom along the 

 Southern coast of England by a fauna indicative of water some- 

 what warmer than that of our present British Channel, of our rivers 

 by the Gyrena fluminalis, and of the land by those mammalia whose 

 remains are present in the breccia at the base of the gravel at 

 Hessle (some of whose remains also, according to Mr. Godwin- 

 Austen, are associated with the marine mollusca in the Selsea mud- 

 bed), took place during the period which, from its having been pos- 

 terior to the elevation of Britain from its great glacial submergence, 

 we have for more than a quarter of a century been accustomed to 

 call post- Glacial. * 



^ A restoration of the supposed geographical features of the British Channel at 

 this time according to my views is given in the fig. No. III. of the Sheet of Maps 

 and Sections which accompanies my paper on the Weald in the 27th volume of the 

 Quart. Journ. of the Geol. Soc. ; see also Geol. Mag. Vol. III. p. 348. 



