Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/136

 region, which, in addition to its extent and difficulty, is nearly void of inhabitants. Whether it be well founded or not, the rocks which form this mountain can be traced, under certain modifications, beyond the boundary here mentioned, and as they add useful illustrations to the subject, while they also serve the purpose of determining a difficult tract in the geological topography of Scotland, I shall make no apology for describing them.

Granite is found at Balahulish, extending round the shore of Loch Leven on its southern side towards Appin, assuming during this course, various aspects; but it is generally grey and small grained, and of the most ordinary appearance and composition, consisting of quartz, mica, and felspar. Superadded to these, it frequently contains hornblende, or else it consists of quartz, felspar, and hornblende, a circumstance which as I have before remarked forms no distinction geologically considered.

It appears here to be the basis on which micaceous schistus and quartz rock repose, both of which conjoined form the group of mountains called Ben na vear, which rises above the house of Balahulish. It is not necessary for the purpose I have now in view to inquire into the further extent of these rocks. Branches of the same granite in no way altered in character pass through the schist, and probably the quartz rock, although I did not detect their actual junction with this last. I can only conclude that as the schist and quartz rock alternate, that vein which traverses the one must also traverses the other: The schist which is traversed by the granite often much indurated, and approaches by various undefinable gradations to a sort of hornblende slate. Masses of a similar substance may be found imbedded in many parts of the granite. Occasionally these masses appear on close examination to be only irregular spots of hornblende, such occur not unfrequently in those granites