James Geikie — On Changes of Climate. 107 



later stages of the Glacial epoch, which preceded the era of great 

 submergence and the accumulation of the kames and esker-drift. 

 But the stony clay or till which is described by Mr. De Kance as 

 underlying the Lower Boulder-clay, represents in all probability the 

 Scottish Till.! 



I think, therefore, it is hardly possible that the Middle Sand 

 series of the north of England can be the equivalent of the 

 Scottish kames. The kames are found, over and over again, to 

 rest upon, and to be made up out of the denuded " boulder-earth 

 and clay," which is the youngest stony clay in Scotland. It is true, 

 indeed, that the later brick-clays occasionally contain a few stones, 

 but no one on that account would think of calling them Boulder- 

 clay. Thus even apart from the fact, mentioned by Mr. De Ranee, 

 that his Upper Boulder-clay underlies in some places true esker- 

 drift, the evidence, I think, is yet sufficiently strong to show that 

 the Middle Sands of the north-west of England cannot be the 

 equivalents of the Scottish Kames. 



Messrs. S. V. Wood and Harmer, in a series of interesting papers, 

 have clearly pointed out a certain succession of boulder-clays and 

 intercalated beds in the eastern maritime districts of England. Mr. 

 Wood, if I follow him rightly, seems inclined to the opinion that his 

 "great chalky boulder-clay " may be the English equivalent of the 

 Scottish Till, the older glacial deposits of England not being re- 

 presented in Scotland. But the Scottish Till, as I have shown, is 

 not merely one single bed of stony clay : in places sheltered from 

 the grind of the old glaciers, it exhibits several intercalated deposits 

 of gravel, sand, mud, and clay, which, along with the separating 

 Till, may very likely represent, to some extent, the middle and 

 lower glacial groups described by Mr. Wood. The series in East 

 Anglia is much better developed, simply, I believe, because that part 

 of Britain has not been subjected to the same degree of glaciation 

 as Scotland. It appears to me highly probable, therefore, that the 

 whole series of Boulder-clays and intercalated sand and gravel beds 

 of the east of England, up to and including the ''purple boulder- 

 clay of Yorkshire," are represented (inadequately, no doubt) by the 

 Scottish Till, boulder-earth and clay, and the subjacent and inter- 

 calated silt, sand, clay, and gravel ; and that the changes of climate 

 which are indicated by the succession of the English drifts referred 

 to, took place before the great submergence which ushered in the 

 period of kames and that of erratics. This conclusion harmonizes 

 with the results obtained by Mr. Wood in co-operation with Eev. J. 

 L. Eome and Mr. F. W. Harmer. These geologists distinctly place 

 the " great denudation and principal unconformity " after the depo- 

 sition of the purple clay of Yorkshire. Thus, in East Anglia, 

 marine gravels rest upon the denuded glacial deposits, and form a 

 sharp line of demarcation between the accumulation of Boulder-clay 

 and the formation of the later drifts, a succession which is precisely 

 the same as in Scotland. 



1 Much of the "pinel" described by Mr. Mackintosh is also in all likelihood the 

 same kind of deposit as the Scottish Till. 



