original regular position and the posterior disturbance of these stratified rocks. The limestone which is here visible, is a portion of an enormous series of beds, which are to be found in a regular position occupying the left ridge which bounds Glen Tilt, interstratified with quartz rock and with different varieties of schist. This regularity of position is destroyed wherever these beds come in contact with the mass of granite which occupies the right ridge before mentioned. Consequently, the limestone involved in the schist and granite now under review, is a portion of a bed the original position of which is perverted and lost. Are we now to suppose that this bed of limestone was originally deposited in its present form with alternating layers of granite? Admitting that the reticulating veins have been the consequence of a posterior intrusion, this cannot possibly be true of the lamina, as independently of the difficulties, or impossibility as it may more properly be called, of such a process, it is plain that the simultaneous flexure and contortion of the laminated mass is the result of the disturbance produced by the granite veins, and consequently that it was deposited before the intrusion of those veins.[1] Must we then allow that there are cases where granite, or a matter resembling it, has been deposited like schist and bedded limestones from solution or suspension in a fluid? In the mean time, however, the igneous hypothesis respecting granite may perhaps allow of another mode of explaining this appearance. It is conceivable that a mass consisting of alternate layers of micaceous or argillaceous schist and limestone, a compound of which abundant examples are seen in the immediate vicinity of the rock under review, might be so acted on by heat
- ↑ Vide Plates 16, 17.
