DRIFTS OF FLAMBOROUGIl HEAD. 415 



before the ice-bhcet reached this area, during wliich a severe cli- 

 mate was acting upon the exposed surfaces of chalk, so that a con- 

 siderable thickness of disintegrated rock may have been formed upon 

 the surface. This would be swept down into the hollow places 

 during the summer Hoods, for the frozen condition of the upper 

 layers of the Chalk probably prevented the ready absorption of 

 surface-water. In the inner recesses of the Wolds, never reached 

 by the North Sea ice-sheet, a siuiiiar deposit, often of considerable 

 depth, has accumulated in high-lying dejiressions, as at Middletoii, 

 Huggate, and ^fowthorpe *, and also in the upper reaches of some 

 of the Wold valleys f ; I'-nd has remained unmodified. 13ut within 

 the area invaded by the ice-sheet this surface-deposit could scarcely 

 remain undisturbed, and under such conditions it may have occa- 

 sionally had erratic blocks and pebbles incorporated with it, as 

 at South Sea Landing and other places, while the Chalk was some- 

 times contorted below it, as at Danes' Dyke J. Its presence below 

 the Basement Clay at Jiridlington, 20 feet below sea-level, and its 

 position in some of the buried valleys of the headland, point to an 

 elevation of the land during its formation. 



There is, of course, nothing peculiar to the locality in the occurrence 

 of this rubble of the country-rock at the base of the drift-series ; it 

 is what is commonly seen in glaciated areas, especially on tiat ground 

 and at low levels §. I3ut, whereas in most instances this rubble 

 m?y be explained as the direct result of the grinding action of the 

 ice-sheet, on Flamborough Head and on the ^\'olds generally such an 

 explanation alone is quite inadequate to account for many of its 

 features, and especially for the distribution of the deposit. 



3. Tlie Basement Clcuj. — I have shown in the foregouig description 

 of the sections, and more fully in another paper |!, that the Lower 

 Clay of Plamborough Head is the northward continuation of the 

 Basement Clay of Holderness. It is now quite clear that, though it 

 includes the scrapings of a boulder-strewn Glacial sea-bottom with 

 an Arctic fauna, the clay cannot on this account be reckoned 

 marine, any more than it can be reckoned Liassic because of its 

 inclusion of large quantities of Liassic debris. The presence of 

 scratched (Fileyj and contorted (^ilamborough) rock-surffices beneath 



* See Rev. E. M. Cole ' On the Oi-igiu and Formation cf the Wold Dales,' 

 Proc. Yorks. G-eol. & Polytechn. So^. vol. vii. (itsTD) p. loi ; and 'Note on 

 Dry Valleys in the Chalk,' ihld. vol. ix. (1887) p. 344. 



r J. R. Mortimer, Pi'oc. Yorks. Geol. & Polytechn. Soc. vol. aH. (1881) p. 378, 

 and Proc. Geol. Assoc, vol. viii. (1883) p. 267, also Geul. 8urvey Mem. ' Dritlield,' 

 p. l«. 



\ There is a close analogy between this chalky rubble and the ' Coombe- 

 Rock ' of the South Downs, and the views here put forward are etsentially tho=e 

 adopted by Mr. Clement Reld to explain that deposit, in Quai-t. Journ. Geol. Soc. 

 vol. xliii. (1887) p. 304. The Coombe-Rock has not, however, been modified by 

 suosequent glaciation, and is probably of newer date than the deposits under 

 discussion. 



§ E. g. T. Mellard Reade, Quart. Journ. Geol. Soc. vol. xxxix. (1883) p. 122 ; 

 Jus. Geikie, ' Great Ice Age,' 2nd ed, p. 21, &c. 



II * Glacial Sections,' (JLc, part iv. supra cit., which treats almost exclusively 

 of tills clay. 



