S. V. Wood,jun. — American and British Surface- Geology. 19 



in tlie Fen district there occurs in certain localities a profusion of 

 the river-shell Gyrena fluminalis, which now lives in the Nile and 

 in the rivers of Thibet and China, and which is fossil in Italy 

 and other places, as well as in the gravels of the Somme, the Thames 

 Brick-earth, and at Barnwell near Cambridge, and which also 

 lived during the later Crag and earliest Glacial formations. The 

 presence of this shell, which seems peculiar to running water, proves 

 that the valleys of the lower grounds were, during the Hessle 

 gravel, occupied by rivers of water and not glaciers, but the valleys 

 of the higher and mountainous regions may at this time have been 

 occupied by glaciers, and, indeed, during the formation of the over- 

 lying Hessle clay, were, as it seems to me, so occupied. The debris 

 shed out by these glaciers, together with that supplied from the 

 coast waste of ground at lower altitudes than the mountains, such as 

 the Yorkshire Wolds and Moorlands, the Durham Permian terrace, 

 etc., appear to me to have furnished the material of this clay. 



The completeness of the break between these formations of the 

 minor glaciation and those of. the major, as well as the considerable 

 period covered by it, is shown partly by the way in which the 

 purple clay (c and d) has been removed by denudation prior to the 

 deposit of the Hessle beds, so that the Hessle clay wrapping over 

 the denuded edges rests in the valleys, which are cut through the 

 purple and down to the basement clay (a), on that clay itself; and 

 partly by the occurrence of the Gyrena in gravels of Hessle age, and 

 of mammalian remains in the breccia at Hessle (bed No. 4 of Sec- 

 tion VII.) ; for these furnish evidence that the interval indicated by 

 this break was accompanied by the introduction of a terrestrial fauna. 



Mr. Thomas Jamieson, in a paper read before the Geol. Soc. of 

 London in 1874,' has endeavoured to show that after Britain had 

 arisen from its great submergence, the valleys of the Scotch High- 

 lands were filled with glaciers, which in some places reached to 

 the sea ; and that to the glaciers of this period the Kame drift of 

 that region is due ; and as I have already observed and explained 

 in detail while discussing the Ohio Eskers,, an examination which 

 I made in the year 1870 of the drift of the Scotch Highlands leads 

 me to agree with Mr. Jamieson in this view. 



We have been furnished with a description of the Glacial fea- 

 tures of the Westmorland mountain district by Mr. J. C. Ward, in 

 three papers read during the years 1873-4-5, and published in the 

 Journal of the Geol. Soc. of London (vols. xxix. xxx. and xxxi.). 

 Mr. Ward considers that we have evidence there of three periods ; 

 the first being that of confluent glaciers, or ice-sheet, the origin 

 of which he regards as altogether British, finding no indication of 

 the action of any ice-cap from the Polar regions. He also observes 

 that he cannot find any facts to suggest a cutting up of this period by 

 several mild seasons. The second period is that of submergence 

 and amelioration of temperature ; and the third that of a minor 

 glaciation which the district underivent subaerially, and in which 

 the glaciers were not confluent, but confined to the valleys. This 

 1 Quart. Journ. Geol. Soc. vol. xxx. p. 317. 



