DRIFTS OF THE VALE OF CLWTD. 



93 



papers, and especially to the recently published Mem. Geol. Survey, 

 " Geology of Holderness," by Mr. Clement Reid, to whom I am in- 

 debted for the revision of my list and for much kind assistance. The 

 percentages have been changed by Mr. Reid's work, and the state- 

 ments of Gwyn Jeffreys and others will have to be modified ; but 

 the main conclusions to which I would draw attention remain un- 

 altered, viz. that " with the Bridlington Crag, notwithstanding the 

 close proximity of the deposits, the marine gravels show little con- 

 nexion" (Clement Reid, p. 69). I am inclined to refer the glacial 

 character of some of the newer marine beds of Eastern Yorkshire 

 to the wasting of old boulder- clay cliffs and the using up of old 

 material, rather than to the recurrence of arctic conditions, and so 

 compare the Arenig land-ice drift of the west with the Bridlington 

 Drift of the east, and the St. Asaph Drift with the shell-bearing 

 sands and gravels of Kelsea and Hessle. 



There is more doubt respecting the fauna of the glacial beds south 

 of the Humber, Searles Wood's Mid-glacial, for instance, in conse- 

 quence of the difficulty of discriminating between the contemporaneous 

 shells and those derived from the Crag, which occurs close by. (See 

 a useful review of the literature of this part of the subject by 

 H. B.Woodward, Proc. Geol. Assoc. vol. ix. See also Jukes-Browne.) 



Table of Distribution of Fossils in Drifts 



Kkynchonella psittacea, Chemn. 



Anomia ephippium, Linn 



Ostrea eclulis, Linn 



Pecten islandicus, Mull 



opercularis, Linn 



pes-lutrse, Linn 



Mytilus edulis, Linn. 



(Modiola) modiolus, Linn. . 



Crenella decussata, Montagu ... 



Nucula Cobboldise, Leathes 



nucleus, Linn 



tenuis, Montagu 



, var. inflata, Hanc 



sp. 



Leda intermedia, M. Sars 



lenticula, Moll 



limatula, Say 



minuta, Mull 



, var. buccata . 



pernula, Mull 



tenuis, Phil 



Pectunculus glycymeris, Linn. 

 Area lactea, Linn. 



Montacuta Dawsoni, Jeffr. 



II. 



III. 



IV. 



VI. 



VII. 



VIII. 



* Column I. St. Asaph; II. Colwyn Bay; III. Moel Tryfan ; IV. Minera 

 &e. ; V. Lancashire and Cheshire ; VI. Macclesfield ; VII. Kelsea ; VIII. Brid- 

 lington. 



