G. W. Lamjjlugh — The Shell-bed at Speefon. 179 



out, but without further signs of shelly sand, which probably 

 therefore thins out as the Neocomian clays rise to a higher level, 

 and we approach the high-water mark of the old estuary. It is, 

 indeed, tolerably certain, that in this exposure the beds have 

 reached their greatest development, for northward from this point 

 the underlying Secondary clays show a steep denudation slope, 

 which reaches the beach at the north end of New Closes Cliff; 

 so that if all the drift were removed, a broad flat terrace of 

 Neocomian clays, coinciding perhaps with the tidal flat of the old 

 estuary, would stretch along under the chalk-scarp. And, as might 

 be expected, it is on the crest of this terrace that the sands are 

 thickest, for in the deeper central portions of the valley the current 

 from the land would probably run too strongly to allow sand-banks 

 to form. 



1 have found traces of the sands here and there amongst the 

 slips across New Closes Cliff, following the denudation slope of the 

 Secondaries till they reach the beach- line, where the sands may be^ 

 seen at the cliff- foot when the sand and shingle of the beach 

 happen to be removed from the base of the cliff. The distinction 

 between upper and lower parts still holds, but the sands are only 

 about two feet thick, and shells are not at all plentiful. 



Northward beyond this they may be seen at intervals between 

 slips, being often little better than a re-arranged form of the 

 Speeton clay, till "The Gill" is reached, where they finally disappear 

 from the cliff- foot. 



In May, 1879, however, there was a very interesting exposure on 

 the beach, nearly opposite the village of Eeighton, about a mile 

 north of "The Grill," and here again I obtained traces of the deposit, 

 and also had direct evidence as to its being older than any Yorkshire 

 Boulder-clay. 



As has been shovvn, in the chief exposure, in New Closes Cliff, 

 the shelly sands are overlaid by a dark Boulder-clay, above which 

 a red Boulder-clay is seen — a parting of gravels occurring between 

 them. I have also mentioned that, if the upper clay be traced 

 northward, it is found to consist really of two separate clays, the 

 division here having been obliterated. The top clay ' I believe to 

 be the northward extension of the " Hessle Clay" of Holderness. 

 The other two form the "Purple Clay" of Messrs. Wood and Rome,'^ 

 but I have also endeavoured to show ^ them to be really distinct, 

 and as good divisions as any of those now i-ecognized, and which 

 may be readily traced wherever the " Purple Clay " is well developed, 

 either north or south of Flambro. The shell-bed is therefore 

 overlaid here by what we may call the " Lower Purple Claj'." 

 The exposure on the beach, however, revealed older divisions. It 

 extended nearly 500 yards, and had a varying width of about 30 

 yards. In it the following beds were seen, appearing to dip slightly 

 towards the cliff: — 



' Proc. Yorkshire Geol. Soc. for 1879 (On the Divisions of the Glacial Beds in 

 Filey Bay). 



2 Quart. Journ. Geol. Soc. vol. xxiv. p. 147. ^ V. supra. 



