AND THEIR MEETING WITH GRANITE. 10J 



in the junction, the progress of the granite vein was visible 

 through the outer part of the granitic mass ; the substance of 

 which last was there in a confused and undefined state : far- 

 ther in, the vein spread wider, and in the space of a few inches 

 more, was quite lost in the general mass. I account for this 

 by supposing, that the granite near the junction being partly 

 cooled, and partly contaminated chemically by the contact of 

 the strata, is rendered less liquid than elsewhere, and that a 

 quantity of more thoroughly liquid matter occasionally and 

 subsequently forces its way through this barrier, and through 

 the contiguous substances. 



We have thus a representation in miniature of one of those 

 events which I conceive to have happened on a large scale in 

 the formation of that mass, which, in its present elevated si- 

 tuation, constitutes the body of our island. One portion of 

 liquid granite, forcing its way among the strata of killas, then 

 lying low and flat at the bottom of the sea, and in a state of 

 softness and pliability from semifusion, has, by its swelling, 

 pressed them into a convoluted shape, and has taken its station 

 among them. By the progress of cooling, this whole assem- 

 blage, both stratified and unstratified, has become susceptible 

 of laceration, and has been rent by subsequent forces acting 

 from below. A fresh stream of liquid granite has penetrated 

 into the rents so formed, and has swelled and spread among 

 the convoluted and broken killas, so as frequently to occupy 

 an extent of many miles, constituting one of our external gra- 

 nitic masses. But this last-mentioned invasion, though doubt- 

 less producing a comparative elevation, has still, I conceive, 

 taken place at the bottom of a deep sea, where our sandstone 

 strata have since been deposited, on the rock both of killas 

 and of granite ; and where the fragments composing that 

 sandstone have undergone the moderate heat by which they 



have 



