REVIEWS. 
271 
level, or two hundred and twenty feet above the Ulleswater ; and it enables us 
to measure with exactness the dimensions of the glacier which formed it. Taken 
from the tarn at the head of the valley, this glacier was three miles in length, 
about five hundred feet in depth at its centre, and from two hundred to four 
hundred yards in width. On the eastern side it was bounded by a continuous 
and nearly vertical escarpment of bedded trap ; but the western side was very 
irregular and indented. The phenomena of this region appear to show: first, a 
period when glaciers protruded far down the main valleys ; secondly, an interval 
when the land was submerged about one thousand two hundred feet or more, 
during which the boulder-clay was spread over the flanks of the hills and valleys; 
thirdly, a period when the laud had been again elevated, and glaciers extended, 
some distance down the minor valleys and ploughed out the drift. It was a 
glacier of this third period which has left the terminal moraine of Grisedale. 
The glacial vestiges of the Highlands of Scotland are on a scale more grand 
than those of the lake district or Wales, in proportion to the greater extent and 
loftiness of the mountains, and their higher latitude. Ben Nevis, in lat. fifty- 
six deg. fifty min., attaining an elevation of four thousand three hundred and 
sixty-eight feet, falls only a little short of the snow line, and is said to have 
patches of snow all the year round in the fissures near the summit. The 
observations which have been recorded regarding the direction of the stria, go 
to prove that the Highlands formed a centre of dispersion, from which the ice- 
streams and bergs radiated in every direction from the central range. 
The southern slopes of the Grampian Hills in Angus and Forfar have received 
a detailed exammation at the hands of Sir C. Lyell. The striations follow 
the lines of the main valleys south-south-east, and several fine examples of 
lateral and terminal moraines are mentioned. Of these the great transverse 
barrier of Glenairn seem to be the most remarkable. The valley of the south 
Esk here contracts from a mile to a half a mile in breadth, and is flanked by 
steep mountains. Seen from below, this barrier resembles an artificial dam 
two hundred feet high, with numerous hillocks on the summit. Its breadth 
from north to south is half a mile. Sir C. Lyell considers this to be the ter- 
minal moraine of the receding glacier, and considers it probable that it once 
banked up the river so as to form a lake, which has since been drained by the 
Esk having cut a channel for itself thirty feet deep on the eastern side. 
The Sidlaw Hills claim particular attention on account of the examples of 
transported boulders which they afford. Separated by the great valley of 
Strathmore from the Grampian range they reach an elevation of one thousand 
five hundred feet. They are formed of Old Red Sandstone, and on their flaiJks 
at elevations of seven hundred and eight hundred feet are strewn blocks of 
gneiss and mica-slate, which have been floated across the intervening space over 
a distance of fifteen miles. One of these blocks on Pitscanby Hill is thirteen 
feet long, and seven across. This is an example, on a much smaller scale, of 
the erratic phenomena of the Alps, where enormous blocks have been trans- 
ported across the great valley of Switzerland from the Mont Blanc range, and 
stranded along the flanks of the Jura hills. The Pierre a hot, one of these 
boulders, is one of the noblest monuments in the world of the transporting 
power of ice. 
The Highlands of Perthshire have been examined along their southern water- 
shed by Buckland and Agassiz, who detail numerous examples of glacial traces 
in the shape of moraines, roches nioutonnees, strise, and perched blocks. 
The wild district of Inverness-shire and Ross-shii-e remain yet to be described, 
as far as its glacial history is concerned. Erom what we know of the adjoining 
regions, however, we may surmise that its long channel-shaped valleys and arms 
of the sea, stretching from the coasts far into the mountains, must have presented 
a series of physical conditions very similar to that of Norway, where the glaciers 
