REVIEWS. 
269 
far-famed Lakes of Killarney. On approaching this region from the east, it is 
impossible not to be struck with the vast accumulation of detritus, vnih large 
boulders derived from the rocks of which the mountains are composed. This 
deposit of the age of the northern drift is spread over the low-lying district of 
Carboniferous limestone which extends to the lower lake. On the western and 
southern sides of tliis lake the mountains rise abruptly and attain at Cam Tual 
an elevation of three thousand four hundred and four feet, and here the glacial 
phenomena are as strongly pronounced as in any part of Wales and Scotland. The 
Elack Valley, one of the most wild and striking, which stretches from the head of 
the lower lake to the base of Macgilly cuddy's Reeks, exhibits these appearances 
in their most marked form. The surfaces of the rocks are here worn into smooth 
oval bosses, lying with their major axes in the direction of the valley, and ex- 
tending several hundred feet up the sides. These polished rockes moutonnees, 
however, assume a singular appearance when traced mto the upper lake. They 
rise above the surface in the form of small oval islands, lying parallel to each 
other, and, though frequently clothed with luxuriant vegetation, are generally 
smooth and bare. It is impossible to give an idea of these ice-moulded bosses, 
protruding their naked backs above the calm waters of the lake, bearing some 
resemblance to a number of up-turned hulls of ships, or to a shoal of whales 
swimming half out of the water." 
Nearly all the main valleys present similar appearances. The rocks, wherever 
freshly exposed, are grooved and striated : the picturesque valley of Glengariflf 
being specially remarkable for the freshness of the ice-groovings and scratches. 
These striae point west-south-west, stretching along the valley till it is sub- 
merged in the sea at Bantry Bay. 
The years 18il-42 appear to have been remarkably prolific in researches inio 
the glacial phenomena of our islands, for we find Professor Agassiz, Dr. Buck- 
land, and Sir C. Lyell announcing consecutively their convictions of the former 
existence of a state of things in these islands, which have their analogues only 
in Greenland, South Georgia, or Tierra del Fuego, at the present day. M. 
Agassiz pointed to the Caernarvonshire mountains as one of the centres of dis- 
persion of glacial and erratic detritus ; and Dr. Buckland speedily followed 
witli details tending to prove that the seven valleys of Snowdonia were once 
occupied by as many glaciers, discharging loads of boulders and gravel over the 
lower grounds or into the sea, and covering the bottoms and sides of those 
valleys with flutings and furrows. He also shows that on the northern flanks 
of this district, boulders and marine drift coming from Anglesea, Cumberland, 
or Ireland, and containing, as shoNAii by Mr. Trimmer, marine shells, have been 
deposited at an elevation of one thousand three hundred and ninety-two feet on 
Moel Tryfane. 
The observations of Dr. Buckland were followed by those of Mr. Darwin, 
and more recently by those of Professor A. C. Ramsay. This author has shown 
that many of the tarns, such as Llyn Llydaw and Llyn Idwal, have been pro- 
duced partly through the damming up of the waters by moraines, as Agassiz 
had previously shown to be the case in the Alps, and Lyell in Forfarshire. The 
same author, m order to account for the fact that several of the mountain tarns, 
as those near the summit of Cader Idris, Moel Wynne and Snowdon, are in the 
form of basins hollowed out in solid rock, has suggested an explanation which may- 
be called " the scooping theory." These tarns are generally surrounded through 
half their circumferance by precipitous walls of rock ; and Professor Ramsay 
supposes that solid masses of ice, descending from these heights, charged with 
imbedded fragments of rock, have actuaUy scooped these hollows, which are so 
numerous in all mountain districts. 
But there is one interesting fact brought out by Professor Ramsay, and 
which, according to my own observation, is repeated amongst the valleys" of the 
