Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/286

 alternating. These veins originate in the mass of granite which forms the mountain, and this observation is important, as I shall hereafter shew that the granite seen in the Criny is a portion of the great central granite mass which forms the whole range of hills on the right bank of the Tilt.

From Glen Criny a succession of schist and quartz rock is to be observed, extending till within a few hundred yards of Gow's bridge; but the bed of the river being here inaccessible, we can only obtain a general view of it. The last bed of quartz rock in this direction is immediately followed by a bed of limestone, and this again is succeeded by an alternation of beds of schist, limestone, and quartz rock for some hundred yards below that bridge, together with masses of porphyry both of a reddish and a greyish colour, but whether disposed in beds or veins I have been unable to ascertain, though I imagine that they are beds, since they seem to conform to the stratified rocks. As this collective mass presents some interesting circumstances it will require a more minute detail.

The position of the whole of these beds is regular, with two very slight exceptions, and they occupy a space extending from 320 yards or thereabouts above Gow's bridge to 200 below it.

We have seen that all the irregularities of the beds take place wherever the granite comes into contact with them. Here there is no granite present, but, on the contrary, the mass of limestone of which these beds form a part, and which has hitherto been found terminating in the bed of the river, is continued to the right hand ridge, and may he traced high up in the hill, where the contact with the granite takes place. The only exception with regard to the