90 REPORT—1850. 
On Traces of Ancient Glaciers in Glenmessan. 
By C. Macraren, F.R.S.E. 
Certain deposits of clay and gravel in Glenmessan (Argyleshire), resembling the 
moraines of glaciers, were described in this communication. The valley of Glenmessan 
is about three miles north-west from Kilmun. The upper part is narrow and steep 
in the sides, and bounded on the east and west by mountains probably 1500 feet in 
height. Two ridges of clay and gravel, lying side by side, cross this part of the valley 
at right angles to its length, the one 77, the other 40 feet in height above its bottom. 
The northern one is about 350 feet long, the southern and higher 320. Both seem 
at first to have extended completely across the valley, the river Messan having sub- 
sequently cut a narrow passage for itself between their east ends and the rock. The 
two ridges are similar in shape, and both are covered with herbage. Externally, each 
resembles the roof of a long thatched barn or row of cottages. At the truncated 
ends, the materials are seen to consist of clay and gravel with a few considerable 
blocks of stone intermingled, and withont any apparent trace of stratification. Below 
these ridges the valley widens, and its bottom assumes the form of an undulating 
plain, on the surface of which, half a mile southward, four detached eminences pre- 
sent themselves. Two of them are sharp ridges 200 feet long and 30 feet high, and 
stand transversely to the direction of the valley ; the other two are in the form of 
flattish mounds, from 20 to 30 feet high, and are placed obliquely to the line of the 
valley. Several large boulders rest on the surface of these ridges and mounds, and 
their materials, position and appearance suggest the idea that they are remnants 
of terminal moraines formed during the gradual and final retreat of the glaciers from 
the valleys of the Grampians. It is confirmatory of this conclusion, that the rocks 
on the sides of the valley exhibit most distinct marks of powerful abrasion. Some- 
times they present a smooth and a rough side, the former always facing the head, 
the latter the foot of the valley; sometimes they are cut into vertical planes 50 or 
100 feet in height. These planes run across the laminz of the slate, are as smooth 
as a wall of dressed masonry, and at many parts show well-marked horizontal strie 
and groovings, such as are seen on rocks in contact with the sides of glaciers in the 
Alps. It seems scarcely possible to account for the abraded and striated surfaces 
of the rocks and ridges and mounds of gravel, except upon the hypothesis that they 
have been produced by glaciers at an ancient epoch. 
Parallel between the Superficial Deposits of the Basin of Switzerland and 
those of the Valley of the Po in Piedmont. By Dr. CHArLEs Martins 
and B. GASTALDI. 
1. Ancient Moraines (part of the Terrain Cataclystique of Necker).—In proceeding 
from the higher to the lower ground in both basins, we find great accumulations in 
the form of ridges, composed of erratic blocks, sand, angular gravel, of striated peb- 
bles, derived from the Alps, and of clay (lehm), all mixed together, and without any 
trace of stratification, indicating the long existence of glaciers at the localities. In 
Switzerland, the towns of Berne, Zurich, Sursee, &c. are built on moraines; also the 
moraine of Mont Sion, between Geneva and Annecy, and finally the great moraine 
of the ancient glacier of the Rhone, which extends from the Fort de l’Ecluse to 
Soleure, along the eastern declivity of Jura, In Piedmont there is the moraine of 
Rivolri at the opening of the valley of Susa ; that of Ivrea formed the ancient glacier, 
which, descending from Mont Blane, Mont Rose, and the mountain of Coyne, filled 
the valley of Aoste, and extended in the plain as far as Calosso. 
2. Scattered Erratic Formation (part of the Terrain Cataclystique of Necker).—It 
is composed of gigantic angular blocks brought from the Alps, of gravel composed of 
striated angular pebbles, and of lehm or glacier mud. These materials have been 
brought by the glaciers at the period of their greatest extension, and show that they 
had not remained long at the place where the materials are found. In Piedmont the 
scattered erratic formation forms a band round the moraines, and is seen on the hill 
of Superga. In Switzerland it covers all the plain from the lake of Geneva to the 
lake of Constance, and penetrates into the valley of Jura. 
3. Glacier Diluvium.—This great formation is formed of rolled and rounded 
