GLACIAL SUCCESSION IN EUROPE. 129 



phenomena of precisely the same kind. My friends and colleagues, Messrs Peach and 

 Horne, had independently come to a similar conclusion ; and the more recent work of the 

 Geological Survey in the North- West Highlands, as they inform me, has demonstrated 

 that after the dissolution of the general ice-sheet, underneath which the upper boulder- 

 clay was accumulated, a strong recrudescence of glacial conditions supervened, and a 

 general advance of great valley-glaciers took place — the glaciers in many places coalescing 

 upon the low grounds to form united mers de glace of considerable extent. 



The development of these large glaciers, therefore, forms a distinct stage in the 

 history of the Glacial Period. They were of sufficient extent to occupy all the fiords of 

 the Northern and Western Highlands, at the mouths of which they calved their icebergs, 

 and they descended the valleys on the eastern slopes of the land into the region of the 

 great lakes, at the lower ends of which we encounter their outermost terminal moraines. 

 The Shetland and Orkney Islands and the Inner and Outer Hebrides at the same time 

 nourished local glaciers, not a few of which flowed into the sea. Such, for example, was 

 the case in Skye, Harris, South Uist, and Arran. The broad Uplands of the south were 

 likewise clothed with snow-fields that fed numerous glaciers. These were especially 

 conspicuous in the wilds of Galloway, but they appeared likewise in the Peeblesshire 

 hills ; and even in less elevated tracts they have left more or less well-marked traces of 

 their former presence. 



It is to this third epoch of glaciation that I would assign the final scooping out of 

 our lake-basins and the completion of the deep depressions in the beds of our Highland 

 fiords. All the evidence, indeed, leads to the conviction that the epoch was one of long 

 duration. 



It goes without saying that what holds good for Scotland must, within certain limits, 

 hold good also for Ireland and England. In Wales and the Cumberland Lake District, 

 and in the mountain regions of the sister island, we meet with evidence of similar 

 conditions. Each of those areas has obviously experienced intense local glaciation sub- 

 sequent to the disappearance of the last big ice-sheet. 



Attention must now be directed to another series of facts, which help us to realise 

 the general conditions that obtained during the epoch of local glaciation. In the basin of 

 the estuary of the Clyde, and at various other places both on the west and east coasts of 

 Scotland, occur certain clays and sands, which overlie the upper boulder-clay, and in some 

 places are found wrapping round the kames and osar of the last great ice-sheet. These 

 beds are charged with the relics of a boreal and Arctic fauna, and indicate a submergence 

 of rather more than 100 feet. In the lower reaches of the rivers Clyde, Forth, and Tay 

 the clays and sands form a well-marked terrace, and a raised sea-beach, containing similar 

 organisms, occurs here and there on the sea-coast, as between Dundee and Arbroath, on 

 the southern shores of the Moray Firth, and elsewhere. When the terraces are traced 

 inland they are found to pass into high-level fluviatile gravels, which may be followed 

 into the mountain valleys, until eventually they shade off into fluvio-glacial detritus 

 associated with the terminal moraines of the great local glaciers. It is obvious, in short, 



