PERMIAN ROCKS OF CLYDE DRAINAGE AREA. 519 



the close of its formation (so far as seen here) volcanic activity had again set 

 in. A volcanic vent is seen at the north end of the Mossgiel tunnel. Car- 

 boniferous Coal-measure rocks extend all round this Permian area, and 

 doubtless under it. 



ARRAN. 



The geological position of the red sandstone strata of Arran had long 

 been a matter of dispute till the discovery on the N.E. shore of a con- 

 glomeratic underlying sandstone which closely resembles that of Mauchline, 

 proved at least that they were of post-Carboniferous limestone date and were 

 in all likelihood of Permian age. (Trans. Geol. Soc. of Glasgow, vol. xi., 

 1898, p. 29.) The sandstones closely resemble those already described, but 

 the conglomerate is entirely different from that of Ballantrae, and that of 

 the Snar Valley to be presently mentioned. It contains pebbles of limestone 

 with at least 29 species of Carboniferous fossils ; the other pebbles consist- 

 ing of quartz, varieties of 'trap, and fragments of sandstone. 



The patches of red sandstone near Corrie and at Maoldon may be of 

 Permian age, and have evidently been influenced, as to their dip, by the 

 granitic nucleus of the island. 



SNAR VALLEY.* 



In the Snar Valley, between Crawfordjohn and Leadhills, there is a sub- 

 oval area of two miles by one mile, its long axis running N.N.W. and S.S.E. 

 With the exception of a few feet of sandstone it is entirely composed of 

 conglomerate with pebbles of greywacke and radiolarian chert. It dips 

 towards Glendowran Hill (1543 feet) and Brown Hill (1603 feet), at about 20 

 on an average. Close to the east boundary, on these hills, the dip becomes 

 reversed and increases to as much as 60, which apparently indicates that 

 since the Permian strata were deposited they have been let down or the 

 hills have been elevated. They rise from 850 to 1350 feet above sea-level. 

 The conglomerate has a considerable resemblance to that of Ballantrae, 

 and like it is occasionally cemented bycalcite, the greywacke pebbles being 

 stained (generally to their centres) of a reddish colour, and occasionally 

 reaching a diameter of two feet. (Trans. Geol. Soc. Glas. vol. xi.) It is seen 

 at one part to rest on the upturned edges of Silurian strata, also stained to 

 some depth by the red colouring matter of the conglomerate. 



At Bothwell the Clyde cuts through red rocks, but they are probably just 

 the upper part of the Coal-measure strata, although some of the beds closely 

 resemble the sandstone of Ballochmyle. 



No fossils having been found in the Permian patches of the Clyde area, 

 it is entirely on lithological and stratigraphical evidence that these remnants 

 of an evidently once more extensive formation have been relegated to the 

 Permian period. 



* For a detailed description of this deposit see the author's paper, Trans. Geol. Soc. 

 of Glasgow, vol. xi., part 2, 1900, page 250. 



