DRIFTS OF FLAMBOROUGH HEAD. 427 



this correlation, in spite of its having received the sanction of S. V, 

 Wood, will not, I expect, be considered sound in view of the Mid- 

 Lincolnshire evidence. However, after having examined some of 

 the Lincolnshire sections, and after close study of much of the 

 literature of the area, I am still inclined to endorse it. 



In Lancashire and some other parts of the west coast the triple 

 division of the drifts * corresponds ver}^ closely with that of York- 

 shire in many important features, such as the frequent presence 

 of a rubble of the local rock under the Lower Clay, the occurrence 

 of shell-fragments in the Boulder-clay and in the intervening strati- 

 fied beds, the differences in character and composition between the 

 Lower and Upper Clays, and the general inconsistency and final 

 disappearance of the stratified beds in certain directions. 



Not that there is anything peculiar to the North of England in 

 this tripartite arrangement of its Glacial deposits, for similar 

 features seem to have been observed all over these islands, and 

 indeed in almost every glaciated region, especially where the ground 

 is low and flat. The concurrence is rendered the more striking 

 by the fact that the bottom clay is almost invariably the darker 

 in colour, usually dark blue, grey, or purple, while the top clay is 

 as commonly reddish or yellowish. It has been suggested that 

 such an arrangement is a necessary result of the action of laud-ice 

 when acting in wide sheets f. 



From the foregoing account it will be gathered that in my 

 opinion there is no good evidence in East Yorkshire for a mild inter- 

 Glacial period, but that, on the other hand, the formation of the 

 drifts, from the Easement Clay upwards, was directly dependent 

 upon the presence of land-ice in the bed of the North Sea, and went 

 on uninterruptedly, though with wide fluctuations of the ice- 

 margin, to the closing stages of the period. But as the higher 

 portion of the Wolds was never submerged, and their lower slopes 

 not always covered, animal life may not have been entirely shut 

 out from the region, and may have existed at times not far from 

 the edge of the ice-field. The occurrence now and again of animal 

 remains, in stratified beds formed near the borders of the glacier, 

 can be thus explained without postulating the total disappearance 



* D. Mackintosh, Quart. Joum. Geol. Soc. vol. xxviii. (1872) p. 388, &c. ; 

 T. MeUard Reade, ibid. vol. xxxix. (1883) p. 83, &c. ; 0. E. De Ranee, ibid. 

 vol. xxvi. (1870) p. 641 ; and Geol. Survey Mem. ' S. W. Lancashire.' 



t Dr. O. Torell, Am. Joum. Sci. vol. xiii. (1877) p. 77 ; Warren Upham, 

 Canad. Naturalist, vol. viii. (1877) p. 327, &c. It is remarkable how well the 

 descriptions of some American Drift-sections would answer for others on this 

 side of the Atlantic. See also Warren Upham on ' Work of Prof. H. C. Lewis,' 

 in Geol. Mag. (1889) p. 159. 



\ Gravels of uncertain age, but apparently Glacial, yielding a few mamma- 

 lian remains, occur in some parts of the East Riding, both East and West of 

 the Wolds. See Geol. Survey Mem. 'Holderness,' p. 50 ; John Phillips, ' Geo- 

 logy of Yorkshire,' 3rd ed. vol. i. p. 13 ; and Proc. Yorks. Geol. & Polytechn. 

 Soc. vol. ix. (1887) p. 407, for examples. 



2g2 



