100 REPORT—1850. 
The results of the researches of M. Barrande will soon be published in extenso ; 
and Sir Roderick Murchison concluded his review of them by exhibiting several 
plates of the forthcoming work, with the accuracy of which he had made himself 
well acquainted by visits to Bohemia, and which he had no doubt would take its 
place as one of the most remarkable geological productions of our century. 
Notes on the Geology of the Southern Extremity of Cantyre, Argyleshire. 
By James Nicot, F.R.S.E., F.G.S., Professor of Geology, Queen's Col- 
lege, Cork. 
The peninsula of Cantyre is very remarkable both for its geographical and geological 
peculiarities. Its general direction from north to south differs widely from the usual 
N.E. to S.W. range of the Scottish mountains. At Tarbet, it is connected with the 
mainland by an isthmus only a mile in breadth, and a depression of the land for a 
few feet would convert it into several detached islands. ‘The great formation of 
mica-slate which runs nearly S.W. along the border of the Grampians, through the 
whole of Scotland, in this place seems to turn to the south; whilst the clay-slate 
resting upon it disappears on the east side of the granite of Goatfell in Arran. The 
geology of this district has, however, been scarcely noticed, except in some incidental 
remarks in the works of Professor Jameson and Dr. Macculloch. 
The oldest or fundamental rock of the district examined is mica-slate, forming the 
wild country round the Mull of Cantyre, the mountain Bengollicn near Campbeltown, 
and most of the high ground north of that town. It is generally a light gray, arena- 
ceous rock, often more resembling a micaceous sandstone than the typical mica-slate 
of the northern Highlands. The beds are also less contorted, and dip at a low angle, 
or about 30° on the average to the east, or correctly to Εἰ. 8° S. Occasionally it is 
connected with a dark-coloured, large-grained, crystalline limestone, in several beds. 
In Knock Scalbert, north of Campbeltown, this limestone group differs in direction 
from the mica-slate, the beds dipping more to the south (EH. 33° S.), and hence it 
may perhaps form a distinct part of the series. The primary rocks are followed by 
red sandstone and conglomerate, which often rest almost conformably on the older 
-strata. This parallelism is seen in Knock Scalbert; on ‘the north shore of the 
harbour; very markedly in Glenramskill Burn; and at the south of the peninsula 
near Keills. In all these places the dip and direction of the two formaticns ap- 
proximate as closely as those of the separate beds in each. The conglomerate is 
often of immense thickness, and consists of rounded blocks, varying in diameter from 
a few lines to three feet or upwards, imbedded in a red ferruginous, sandy basis. 
The blocks have a very local character, being in some places almost exclusively a 
clove-brown porphyry ; in others, hard sandstone or horustone; in others, again, 
quartz or trap rocks. It is remarkable that no fragments of the mica-slate on which 
they rest, or of other primary rocks, were observed in these conglomerates. The 
red sandstone on the east and south-east coast of the peninsula is often almost a 
tufa, and consists merely of the materials of the claystone porphyries, with which it 
seems in part at least contemporaneous. 
To the west of Campbeltown, in the low valley named the Laggan of Cantyre, coal 
has long been wrought. The true character of these beds, as a portion of the great 
central coal-field of Scotland, was pointed out by Prof. Jameson in his ‘ Mineralogical 
Travels.’ Dr. Macculloch, in his “ Western Isles,’ seems to have adopted the same 
opinion, but afterwards, in his map, coloured this region as lias. The remains of Le- 
pidodendra, Sigillarie, Stigmaria, and other plants found in the coals, as well as in 
the connected shales and sandstones, prove the true age of these beds, and no trace 
of lias fossils was anywhere seen in this place. The coal is broken up by dykes; and 
in Tirfergus Burn, where some fine sections are exposed, they are seen to rest upon, 
and to be overlaid by trap. The igneous rocks are chiefly claystone and felspar por- 
phyries, some of them, like those in Davar island, of great beauty; others, as at Kil- 
kivan, containing large fragments of jasper or altered shale. Augitic trap rocks also 
occur, especially to the east of Southend, and connected with the limestone series 
north of Campbeltown. In the cliffs south of Losset, veins of trap are seen rising 
—— SF 
—_ ν 
