NORTH-WEST OF ENGLAND AND NORTH WALES. Ill 



other. The " Middle Sands and Gravels " are supposed by some 

 to represent " Interglacial," and by others " milder " conditions, in 

 consequence of the stones being all rounded and unglaciated. If this 

 be the case, what do the sands and gravels of St. Bees represent ? 

 They are even a more distinct deposit, and overlie a lower clay with 

 an eroded surface : but here the conditions are reversed ; for the sands 

 and gravels contain in places more and larger blocks than the 

 " Lower Boulder-clay" of Blackpool, and they are full of contortions 

 and evidences of violent action of some sort. 



It is noticeable that the Blackpool Drift lies upon an extensive 

 district of the Keuper marls, and Mr. Binney specially notices 

 as " an interesting fact" the "quantity of both granular and 

 fibrous gypsum and waterstone from the upper red marls of the Trias " 

 occurring in bed 4 (the lower clay). I have no doubt that the 

 greater abundance of sands and gravels in the Drift here is due, the 

 first to the abundance of sand-producing rocks in the uplands, and 

 the second, together with the preponderance of stones in the lower 

 clay, to proximity to the mountains of Westmoreland and Cumber- 

 land. It is also noticeable that in the neighbourhood of the Carboni- 

 ferous hills the Boulder-clay possesses a much greater proportion of 

 rocks that have come from these hills. 



At Carnforth the shingle and large blocks partake of the nature 

 of the rocks of the valley in which they are situated. 



At Grange we have another striking instance of the effect of 

 drainage-lines on the nature of the Boulder-clay ; for here it is 

 richly calcareous, being largely made up from the Mountain-lime- 

 stone rocks of the valley of the Kent. 



At Rampside the Boulder-clay overlies Permian rocks ; and it is 

 also far from improbable that the Keuper marls may extend from 

 Fleetwood across Morecambe Bay in that direction. 



At St. Bees the lower clay has that purple haematitic colour which 

 would lead to the belief that its origin has been local ; and the sands 

 and gravels evidently have been formed from the detritus of the 

 Permian and perhaps Carboniferous sandstones mixed with that from 

 the Silurian mountains of Cumberland. 



Drift of the North Coast and Mountain-District of North . 

 Wales. 



At Colwyn is a ballast-pit used by the Chester and Holyhead 

 Railway : a very great amount of material has been taken out of it. 

 I examined it in 1872 and again in 1874. In descending order is a 

 bed of yellowish- white clay and shingle, from 2 to 3 feet thick ; red 

 brick-clay with blue facings and containing only a few stones, about 

 12 feet ; gravel and shingle-ballast, about 25 feet ; yellow stratified 

 sand not bottomed, tested to 20 feet deep. 



These dimensions will not by any means hold good over the whole 

 area, as by a comparison with my notes in 1872 it appears that the 

 clay lies in lenticular patches interbedded or wedged in with other 

 strata. The stones of the ballast are all rolled ; and among them are 

 granites, most of the stones being of local Welsh rocks. 



