106 James Geikie — On Changes of Climate. 



and the American (1) "unmodified drift," and (2) "moraines." These 

 marine beds {i.e., kames, eskers, and osar) invariably occupy this 

 position, and as they do so over such a vast extent of land in the 

 northern hemisphere, they come to form a kind of datum line. If 

 similar deposits occur in England, and if it can be shown that those are 

 clearly of more recent date than certain other glacial accumulations, 

 then these last must necessarily be to some extent the equivalents 

 of the Scottish Till and associated beds. It is in the highest degree 

 unlikely that the Glacial epoch in England differed materially from 

 the same epoch elsewhere ; yet the conditions under which the 

 glacial and interglacial accumulations were laid down may have de- 

 parted considerably from those that obtained in higher latitudes and 

 in mountainous regions. We should naturally expect that the dis- 

 tricts least exposed to the intensity of glacial action will contain 

 more varied and more abundant series of deposits than those areas 

 which have been subjected to a greater degree of glaciation. If, 

 even in Scotland and North America, interglacial beds occur in the 

 Till and "unmodified drift," surely in the low-lying districts of 

 England these should be much better developed. And such, indeed, 

 is the case. Both in the east and north-west maritime regions of 

 England there occur beds of sand, gravel, etc., included between 

 glacial deposits, just as in Scotland sand, clay, and gravel are over- 

 lain and underlain by till. The English stony clays are partly 

 ground moraines and partly also deposits from floating ice; while 

 others would appear to have been thrown down at or near where 

 glaciers terminated in the sea, and hence resemble in origin the 

 boulder-earth or clay of certain maritime districts of Scotland. 



Some years ago Professor Hull showed that in Lancashire there are 

 two Boulder-clays, separated by an intervening series of sand-beds. 

 My colleague, Mr. De Eance, has since pointed out that under- 

 neath the lower of these Boulder-clays there occurs a deposit of Till 

 answering in all respects to the Scottish Till, and being in Mr. 

 De Eance's opinion a product of land-ice.^ The overlying Boulder- 

 clays he thinks are clearly of marine origin, that is to say, they have 

 been deposited upon a sea-bottom. He writes to me also that the 

 " Upper Boulder-clay " is covered by esker-drift. This being so, 

 it would follow that the Lancashire Till and Lower and Upper 

 Boulder-clays, with their intervening deposits of sand, are the 

 equivalents of the Scottish Till and interglacial beds. There is 

 nothing absurd in supposing that while some portion of the Till was 

 being formed in Scotland, marine Boulder-clay was accumulating 

 here and there in England. Yet the descriptions given of the Upper 

 and Lower Boulder-clays of the north of England tally better with 

 the character of the Scottish Boulder-earth and clay than with that 

 of the Till ; and the Lancashire beds may therefore represent those 



^ Mr. Hull was the first (1863) to point out clearly the threefold division of the 

 drift of Lancashire into Upper and Lower Boulder-clay with the intervening Middle 

 Sands (see his Memoir, Mem. Lit. and Phil. Soc. of Manch. 1865, p. 449). Mr. 

 Binney had, however, previously mentioned the existence of sand-beds in the Boulder- 

 clay, but these beds he believed to be of inconstant occurrence. 



