Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/37

 Oransa, the point being much less accurately defined on the eastern than on the western shore. The shores which it forms are generally flat and shelving, but in some particular places, as at Tormore, it rises into high cliffs. The whole tract is however but little interesting, since the uniformity of this rock is only varied by the occasional occurrence of veins of trap and of quartz. If I could determine that the beds of mica slate had a regular position, I would say that they were succeeded by quartz rock, and that this rock terminated near Loch Eishort, being followed by a succession of rocks to be described immediately; but to determine such a succession, a regular disposition is indispensable, since, without that, the uppermost in place may not always be the uppermost in order. I must therefore content myself with remarking that the quartz rock follows the mica slate in geographical position, and that its main body will be seen occupying two hills which lie above Ord, from which the skirts reach to the shores of the southern boundary of Loch Eishort. The mica slate has no peculiarity of structure or of aspect, such as to render a detailed description of it necessary, but I think it proper to remark, that like many other districts of the western isles which contain this rock as the basis of their structure, it is by no means so unmixed as it is generally met with in the extensive tracts of it which occur on the main lands. On the contrary, it is frequently found passing into clay slate as well as into talc and chlorite slates, affording an example like Arran, Isla, and Jura, of the intimate geological union which subsists between these several substances. Of the quartz rock I may remark that it is extremely compact, of a highly crystalline aspect in general, and that its weathered surface is so white as to render the hills which are formed of it distinguishable at a great distance by their snowy appearance, while at the same time it is frequently varnished, as it were, with the