388 PKOCEEDLNGS OJF THE GEOLOGICAL SOCIETY. [May 8, 



Discirssiois^. 



Prof. Ramsax agreed with the author as to the existence of these 

 rock-basins in the Yorkshire area, and as to the absence of marine 

 drift on great part of the slope of the Pennine chain. The terminal 

 moraines had to some extent become obscured by the washing-in of 

 soil by rain ; but their ancient existence in many of the Yorkshire 

 valleys was indisputable. The features of the country were, more- 

 over, in many instances such as could not be reconciled with the 

 deposition of the drift by marine action. 



3. On a Sea-coast Section of Botjlder-clat in Cheshike. 

 By D. Mackintosh, Esq., F.G.S. 



The threefold division of the great north-western drift*, established 

 by Professor Hull, extends into the peninsula of "Wirral, if not 

 further south, in Cheshire ; and I have found it strongly marked 

 near Padeswood station, Flintshire f. To the south of the Mersey, 

 the Lower Boulder-clay becomes very attenuated or patchy, while the 

 upper or brick- clay becomes thicker or more generally diffused. In 

 many places the upper clay is underlain by extensive and persistent 

 deposits of non-glacial sand and gravel (attaining at Gresford a 

 thickness of 150 feet) $, which rest on rock, excepting where they 

 are underlain by a few remnants of the lower clay which escaped 

 denudation. In other places the upper and loAver clays coalesce. 

 One of the best instances of the two clays in contact, with their dis- 

 tinctive characteristics still preserved, may be seen at Dawpool, on 

 the jST.E. side of the estuary of the Dee. Prom Parkgate the lower 

 clay (with large boulders), under a thin covering of the upper clay, 

 may be traced nearly all the way to the Dawpool cliff- section §, 

 which reaches about 50 feet in height, and extends for a distance of 

 three miles. In the part of this section S.E. of Dawpool cottage, 

 where it has not been obscured by talus or the effects of rain, the 

 upper may be seen to be separated from the lower clay by a line 

 (either winding or straight), which in some jDlaces is so sharply de- 

 fined as to indicate that the top of the lower clay had been cleanly 



* This classification does not include the comparatively local and more an- 

 cient blue clay, the relative position of which I have traced through the We.st 

 Hiding of Yorkshire, Cumberland, and along the coast of North Wales. 



t Here some portions of the middle gravel and sand have been converted into 

 "rockery" by the percolation of water charged with carbonate of lime from the 

 overlying clay, similar to what may be seen in many places along the east coast 

 of the Irish Sea. (See paper by the author on the Drifts of N.W. Lancashire, 

 Quart. Journ. Geol. Soc. vol. xsv. p. 411.) 



X Here, as in many other places, the sand and gravel rise to the surface from 

 beneath capping patches of the upper clay. Near Oswestry, the sand and gravel 

 form eskers, in some instances capped with the upper clay. Very striking eskers, 

 enclosing hollows with no outlet, may likewise be seen near Oakmere, and in 

 other parts of Cheshire. 



§ I visited the Dawpool cliffs four times, at intervals, with the object of finding 

 f t-esh faces exposed by clay-slips and the action of high tides. 



