Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/43

 point it out so distinctly. The certainty of a transition between these two rocks is equally well marked by another circumstance, although that indication does not appear at Loch Eishort; namely, by the alternation of the beds of schist with the red sandstone, a phenomenon to be observed at Loch Scavig, as I shall presently show. Following this sandstone it is to be seen forming a considerable part of the hills which rise on the northern side of Loch Eishort, and extending along that shore as far as the farm of Borrereg where it ceases. The beds succeed each other with great regularity, and are of considerable thickness; as far as I should judge from a rude estimate formed by comparing the measures of their edges with the space which they occupy, I should imagine that the collective mass does not here fall much short of a thousand feet in thickness, tallying in this respect very nearly with the dimensions which it seems to maintain in Rum as well as in Soa, both of which I have no doubt are different portions of the same rock.

This red sandstone is also found skirting the southern shore of Loch Eishort in different places, and is particularly conspicuous at the castle of Dunscaich, a building of no high antiquity, but situated on a rock, the traditional residence of Cuchullin “ King of the Isle of Mist.” This position is readily explained by observing that the line of Loch Eishort crosses that of the direction of the sandstone in an oblique manner, leaving thus a portion of it on the southern shore; it is here often in contact with the white quartz rock, the intermediate blue rock having disappeared. From this I should be inclined to suspect that there is a real chasm between the conjoined rocks consisting of mica slate and quartz rock, and the stratified ones now under review, how much soever some of their portions may appear consecutive. I have pointed out at some