CUMBRAY (GREAT). GEOLOGY. 477 



bourhood, it contains beds of the conglomerate generally 

 attached to the sandstone. The' finer varieties however 

 predominate ; nor do the beds present those various sub- 

 stances which occur among them in Arran, and, although 

 more sparingly, in Bute. Almost the only exceptions are 

 found on the shore at Millport, and in two small islands 

 which form the little harbour at that place. These consist 

 of beds of white and of grey sandstone ; the former being 

 predominant, and resembling those which are found in 

 Arran at Corry. The latter are in small quantity, and 

 appear to derive their colour from a portion of blueish 

 clay entering into their composition. There is also a 

 small quantity of limestone to be seen in the island, which 

 has been wrought for agricultural purposes. Appearances 

 of coal have also been observed, and some attempts were 

 made to ascertain its extent by digging. But these were 

 not attended with success, nor does there appear any 

 temptation in an economical view to pursue these indi- 

 cations. As a geological fact it is no longer interesting 

 after the description of Arran, since it evidently belongs 

 to the same variety occurring there at the salt pans. 



The sandstone of the great Cumbray dips, in a general 

 way, towards the north, in an angle, at a medium, of 

 about ten degrees. This remark is not to be taken strictly, 

 since, as in most other situations where they occupy low 

 angles, the strata, from their undulating disposition, pre- 

 sent different elevations, and even in some cases become 

 horizontal. 



It might have been expected from the structure of 

 the adjoining coast, as well as from that of the little 

 Cumbray and of Bute, that overlying trap would have 

 been found in this island also. It does indeed occur, 

 but in very small quantity ; being limited to a minute 

 patch existing on the western shore, where it is indicated 

 in the map and in the general section of these islands.* 



* Plate XXXIII. fig. 3. 



