KKVIEWS. 
330 
again declined ; and the terminal nioniiues of tiic Rhone glacier, arranged oou- 
centrically one within another, bear witness to its recent gradual diniiuution. 
The great (lorncr glacier of Monte llosa, also, is even now steadily advancing, 
and is said within the memory of men not old, to liave already swallowed np 
forty chalets and a considerable tract of meadow-land. But all such historical 
variations in the magnitude of glaciers are trilling compared with their wonder- 
ful extension in pre-nistoric periods. There is, perhaps, scarcely a valley m tlio 
High Alps in which the traveller, whose eye is educated in glacial phenomena, 
will not discern symptoms of the former presence of glaciers where none now 
exist ; and in numerous instances, far from requiring to be searched for, these 
indications force themselves on the attention by signs as strong as if the 
glacier had disappeared but a short time before the growth of the living vege- 
tation. So startling indeed, are these revelations, that for a time the observer 
scarcely dares to admit to himself the justness of his conclusions, when he finds 
in striations, niorauies, roches moutonnces and hlucs perches unequivocal marks of 
the former extension of an existing glacier more than a long day's march 
beyond its present termination ; and further, that its actual surface of to-day is 
a thousand feet and more beneath its ancient level." 
As it is with the glaciers of the Aar, which the professor selects as examples, 
so is it with many other alpine valleys, and so has it been in North Wales. 
After this foUow interesting observations on the disappearance of moraines, 
the former state of the Grimsel, the Aletech glacier, the Kirehet, on the inter- 
esting question whether a glacier ever reached the Jura? and on the great 
percbed blocks of Monthey, one of them twenty paces in length, and eight 
thousand or nine thousand tons in weight. 
These blocks lie in great quantities m and upon sandy gravel roughly strati- 
fied, comparable more in their semi-angular character to the partially-rounded 
chalk-flints of our ordinary " drift" gravels. " Similar drift-like strata encircle 
the Lake of Geneva, rising high above its level, and thence range across the 
low lands of Switzerland, at the base of the Jura towards Zurich and Schaff- 
hausen, covermg the hiUs hundreds of feet above the level of the lakes of 
Zurich and Zug, each of which lies more than a hmidred feet above the Lake of 
Geneva. 
"If this view of the subject be correct," it is argued, "it foUows that 
during part of the period when the North of Europe w'as submerged to receive 
the drift, Switzerland also lay ■beneath the sea, at least two thousand feet 
beneath its present level, that being about the height of the blocks of Monthey 
above the sea." 
The ancient glacial phenomena of Switzerland are then shown to accord with 
those of North Wales ; and the tract between the Snowdon range and the 
Menai Straights is described, in which we are favoured with examples of blocs 
perches, roches moutonnees, erratic blocks, polished and striated rocks, and 
moraines, by which the region of Snowdon is brought prominently before us as 
the site, in geological and pre-historie times, of mighty glaciers^ of which the 
only evidences that now remain are the inscriptions they have themselves en- 
graven, ages since, in their irresistible passage. 
Snowdon, the highest and noblest mountam of the district, "is bounded on 
three sides by six vast hollows or valleys, which have been scooped out from 
time to time in the rock-masses of which the mountain is formed. In one of 
these, Cwm-glas, some of the most perfect remains of glacier-action, are to be 
found in the form of moraine-debris and heaps of clay, boulders, and angular 
blocks identical in composition and in general aspect with the Swiss moraines." 
Professor Ilamsay then proceeds with others of these valleys describing their 
beauties and their evidences of ancient glacial phenomena, coming to the con- 
clusion that Snowdon formed the centre of six glaciers having an ice-thickness 
