62 S. V. Wood, Jun. — Sequence of the Glacial Beds. 



depressed to an extent sufficient to bring the sea up to the 1390 feet 

 level. 



More important than this, however, is the fact that the Middle 

 Glacial is overlaid by the great chalky clay (e") which forms the 

 largest member of the whole series, both in thickness and extent, 

 covering the chief parts of many counties, and possessing a thickness 

 that seems, before denudation reduced it to all thicknesses, to have 

 generally been 100 feet, and sometimes to have much exceeded this. 



During the accumulation of the whole of this clay the Chalk was 

 undergoing its icy degradation, and when, therefore, it is scarcely 

 probable that the land could have descended to such a depth as would 

 bring the sea up to the Moel Tryfaen level. And more especially 

 does this appear in the fact that from a section of this clay, overlying 

 the Middle Glacial, I obtained a piece of the Eed Chalk that nowhere^ 

 rises to elevations exceeding 300 feet, and is usually much lower. 

 So far as its bearing upon the relation of the underlying Middle 

 Glacial to the Cheshire and Moel Tryfaen beds is concerned, this 

 occurrence of lumps of red chalk at the base of the great chalky clay 

 is as significant as if it occurred at the top. 



It therefore appears to me, as clear as anything connected with 

 this difficult subject can be, that the Moel Tryfaen bed must be 

 posterior to all the beds from Ti up to and inclusive of that wherein 

 the Chalk begins to disappear, viz., e' ; because the Molluscan 

 evidence, as far as we have really got at it, and the physical evidence 

 go hand in hand together without a contradiction. 



How far this Moel Tryfaen bed may be identical in time with the 

 bed e, a clay formed without any contribution from the Chalk (and, 

 as it appears to me, under a great submergence that had engulfed 

 the Chalk strata beyond the reach of the degrading envelope of ice), 

 I venture not to saj'^ ; but as the period of the greater emergence, 

 to which I have before adverted, can scarcely have been other than 

 of long duration, there seems ample scope for placing the Moel 

 Tryfaen and Macclesfield sands in it in the order of their relative 

 levels ; the highest being the oldest, and the lowest the newest. 

 Nor does there seem to me to be anything in the evidence offered 

 by Mr. Darbyshire's lists that is repugnant to this, such difference 

 as exists between the fauna of Moel Tryfaen and that of the Cheshire 

 beds rather favouring it ; the fauna of the highest bed, that of Moel 

 Tryfaen, departing somewhat less from the Arctic character than 

 the others. In this point of view they would seem to belong to the 

 group d; none of them to the newest of that group, and Moel Tryfaen 

 among the very oldest. 



There seems, however, some dispute as to the position of the 

 Cheshire and Lanccishire fossiliferous sands relatively to the Boulder- 

 clay of those counties, some Geologists regarding them as identical 

 with the sands which intervene between the Boulder-clays — or, 

 perhaps, intercalated in the Boulder-clay — of that part, and some 

 not. If that identity do exist, I have, I think, pointed out enough 



' I think that this holds good even if we suppose the fragment to have come I'rom 

 one of the pink bands of the true chalk. 



