ARRAN. GEOLOGY. 343 



Machrie, the sandstone once more appears, extending to 

 the lorsa river where it terminates. It is not to be seen 

 from hence until we arrive at Loch Ransa ; beyond which 

 it occurs again, accompanied by various other secondary 

 rocks and continued in an uninterrupted manner to Bro- 

 dick, the point from which this description commenced. 

 As the Machrie rises from the east shoulder of Ben 

 huish and not far from the eastern shore, it will be found 

 to separate the whole of the sandstone, together with the 

 trap, from the granite and schist ; with the exception of 

 the narrow line of the former that skirts the shore from 

 Brodick to near Loch Ransa. 



The rocks which form the next most conspicuous tract 

 on the shore, are of a schistose nature and of various com- 

 position ; and they are found along the whole line from 

 the lorsa to Loch Ransa. To the north of this place 

 they retire within the outer belt of sandstone, occupying 

 a narrow space between that rock and the granite in 

 some parts, and, in others, intruding into several of the 

 valleys which descend from the high mountain group 

 of the northern division of the island. But they are 

 not found beyond Brodick on the eastern, nor the lorsa 

 on the western side ; a tolerably decided mineralogical 

 line being here drawn between the two divisions of 

 the island ; and the sandstone only, or latest stratified 

 rock, being common to both. The lofty summits of 

 the northern division consist entirely of granite ; which, 

 to whatever unknown depths it may extend, rarely occupies 

 the valleys or lower skirts of these mountains, which are 

 formed either of the schists, or of the sandstone strata 

 already described. 



It is difficult to give any accurate idea of the districts 

 occupied by the several kinds of rock which constitute 

 all that part of the southern division of the island which 

 is not sandstone. The gently rounded forms, or flat 

 surfaces of these hills, are so favourable to the accu- 

 mulation of soil, and that soil is so concealed by deep 



