406 Searles V. Woodjun. — Sequence of Olacial Beds. 



V. — Further Eebiarks on the Sequence of the Glacial Beds. 

 By Searles V. Wood, jun., F.G.S. 



THE paper of Mr. Hull, " On the General Eelations of the Drift 

 Deposits of Ireland to those of Great Britain," in the July 

 number of the Geological Magazine, induces me to recur to one by 

 myself on the Sequence of the Glacial Beds, Vol. VII. p. 17 of the 

 same Magazine. 



In that paper I adverted to what seemed to me to be illusory in 

 the classification of the Glacial beds, viz., the intercalation of a 

 formation of sand or gravel between an under and an overlying 

 Boulder-clay (Vol. VII. p. 20, foot-note) ; and I endeavoured to 

 show that, though to be received with due care, the evidence of 

 organic remains should have its weight, and go hand in hand with 

 the physical evidence in this classification ; and attention was called 

 to the antagonism that seemed to exist between the molluscan evi- 

 dence afforded by the Middle Sands of the North-west of England 

 and that afforded by the Middle Sands of the East. Since then this 

 antagonism has come out more distinctly ; for while Mr. Harmer 

 and I have made considerable additions to the fauna of the Middle 

 Glacial Sands of East Anglia, the former took the opportunity, when 

 attending the British Association Meeting in 1870, of collecting from 

 the Middle Sands of Blackpool Cliff; and Mr. T. M'K. Hughes (who 

 sent me all he could collect) has tried to obtain the same molluscan 

 evidence at St. Asaph ; down to which place, and over the northern 

 portion of Wales, it would seem (from the observations of Mr. 

 Hughes around St. Asaph, and of Mr. H. F. Hall about Llandudno), 

 the Lancashire arrangement of an Upper and Lower Boulder-clay, 

 divided more or less by sand, prevails. 



In the paper referred to, I ventured to suggest with some con- 

 fidence that a parallelism might perhaps be found between the fauna 

 of the East Anglian sands and that of the so-called Crag gravels of 

 Aberdeenshire, described by Prof Jamieson ; but this also has failed, 

 as Prof. Jamieson kindly sent the specimens he had obtained up to 

 me for examination ; and they proved to be derivatives in the gravels 

 in question, many of them being filled with a matrix foreign to this 

 gravel, which had been rolled with the shells prior to their deposit 

 in it ; and although they clearly showed that some bed of Crag, or, 

 more probably, of very early Glacial age, had existed in the North- 

 east of Scotland (and been destroyed probably by the ice-grind of 

 some later Glacial epoch), yet ihej threw no light on the relation of 

 the Aberdeenshire gravel to the East Anglian Mid-glacial. 



Last year Mr. Harmer and I made a superficial examination of the 

 Glacial beds from Yorkshire (which was the northernmost limit to 

 which our field knowledge of those beds previously extended) as far 

 north as Inverness and Cromarty ; and the conclusion we came to was 

 that these so-called Crag gravels of Aberdeenshire were but a part 

 of the great expansion of Boulder-bearing sand and gravel which, 

 overlapping (and about Inverness resting on) the Ked Boulder-clay 

 of Cromarty, occupies a great part of the maritime borders of the 



