Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/133



A similar greyish basis with dispersed crystals of hornblende only.

A basis of hornblende with distinct crystals of felspar; of a porphyritic character.

An uniform mixture of hornblende and felspar, approaching to common greenstone, and at length not to be distinguished from it.

These latter varieties appear to form a regular series of a transition from porphyry to trap, of which I shall immediately speak; first remarking that besides these leading varieties which I have now described, there are many others which it would be superfluous to notice, as the variations of colour, aspect, and composition, are endless. Together with the veins of decided porphyry, various parts of the mountain are intersected by veins of grey rock, having as I have just remarked, the general character of the trap rocks, and sometimes porphyritic. Veins of perfectly characterized basalt also occur in some places, and these, or fragments of them may in particular be observed in great quantity strewing the top of the first summit, (that one which is marked by two cairns,) and laying fair claim to an equal antiquity with the veins of porphyry. It is easy to procure detached specimens of the junction between the granite and basalt in great variety and abundance. The line of junction is in all cases clear and well defined, but does not admit of ready separation even after long exposure to weather. My observations on the base of the hill were terminated here, some way before the place where the foot of Ben Starive interferes with that of Cruachan.

I have already said that in ascending Cruachan the schist soon disappears: at the same time the accumulation of soil and the covering of plants are so great, that it is scarcely possible to meet with the natural rock for at least half the ascent. Many masses which