Of a New Granite Tract in Arran. 19 



tion of it, as has hitherto been done, from the sandstones underlying 

 as even a rudimentary development of the New-Red system. 



Now, this remarkable difference in physical aspect, as well as the 

 extraordinary variety of geological phenomena which the island exhibits, 

 alike arise from a single peculiarity often overlooked by those who have 

 undertaken to describe it. This consists in the abnormal position of 

 the granite nucleus. Granite usually forms an anticlinal axis to the rocks 

 amid which it rises ; these being symmeti'ically disposed on opposite 

 sides of it. But in Arran it is not so ; the granite has been protruded 

 close to the outer or eastern border of the slate rocks, so as to come 

 almost into contact on one side with the newer sedimentary strata. So 

 near is it, that the slate band between it and these strata, on the 

 hill side west of Corrie, is only a few yards in thickness ; and it is even 

 probable that in some places it is in contact with the sandstone. The 

 protrusion of so large a body of igneous rock by plutonic fires, along the 

 line of junction of the old slates and secondary formations, and its ele- 

 vation to so great a height in a space so limited, have produced all 

 those varied and interesting phenomena which have given so much 

 celebrity to Arran, and rendered it such an admirable field of study. 



Such being the remarkable position of the granite in the northern 

 mountains, it is not perhaps more than was to be expected, that in its 

 protrusion from beneath sedimentary formations already deposited before 

 it was raised to the day, this granite should also pierce through and appear 

 as an intrusive rock among them. Yet its occurrence in such a situation 

 long escaped notice, and was not observed till 1837, when Mr. Eamsay, 

 in his careful survey of the island, discovered it amid sandstones of car- 

 boniferous age on the west side of Glen Cloy. M. Neckar, however, was 

 the first to describe the district, which he named Ploverfield, in 1839. 

 This granitic outburst, and the interesting attendant phenomena, are well 

 and fuUy described in Mr. Ramsay's admirable Guide, and need not now 

 be further referred to. Our own inquiries have given a very considerable 

 extension to the Ploverfield granite ; and in the summer of 1855, we 

 were so fortunate as to discover another tract of granite, overlooked by 

 all previous observers. 



Driving along the lower portion of the String road towards Shiskin, 

 with a party of friends on an excursion to King's Cove, I noticed an 

 extensive talus of blocks reaching from the base of a high cliff on the 

 left, to wtihin a few hundred yards of the road. These struck me as very 

 unlike the blocks of sandstone, which strew the surface all along on that 

 side ; and going up to the boundary of the talus, I found that it was 

 composed of granite blocks. I then also perceived that the cliff itself 

 was formed of granite ; and it struck me as remarkable that on a route 



