24 Rev. A. Sedgwick and Mr. Murchison 07i the Geological 



These phsenomena, and the conclusions derived from them, have been so 

 often stated, that we only mention them in this place by way of introduction 

 to the conclusions which follow from the relations of the same granitic nucleus 

 to those secondary rocks of the neighbouring coast, which we now proceed 

 to describe*. 



§ 2. Coast section from Loch Ranza to Brodick. (See Plate III.) 



Having thus in a general way explained our objects in writing this paper, 

 we now proceed to describe in detail the coast section from Loch Ranza to 

 Brodick, which exhibits at the same time the succession of all the secondary 

 deposits, and their relation to the inferior rocks which form the nucleus of the 

 northern part of the island. 



In following the coast southwards from Loch Ranza, a patch of red sand- 

 stone and conglomerate of about three hundred yards in length occurs upon 

 the shore under the farm of Newtown, resting unconformably in a depression 

 of the schist ; the sandstone dips at a moderate angle to the N.W., whilst the 

 schist is highly inclined to the N.N.E. The junction of these rocks is well 

 worthy of notice, the bed of conglomerate for a foot or two in depth appear- 

 ing to graduate into the chlorite schist, and exhibiting lines of slaty cleavage. 

 Near this place several trap dykes penetrate through the sandstone and schist. 

 At AuUmore (the large burn) the schist finally recedes from the shore, and 

 the strata of red sandstone, consisting of coarse conglomerate alternating with 

 beds of fine sandstone, rise in the clilT and form round-topped hills of the 

 elevation of eight or nine hundred feet, from the side of which a vast ecroule- 

 ment called the Screetenf has encumbered the beach with fragments ; one of 

 the largest of which. The Cock, is a well known landmark, and is laid down 

 in all the maps of the island. 



To the south of the Screeten the sandstone and conglomerate form a succes- 

 sion of lofty terraces ; and their junction with the slate range of the interior is 

 marked by a deep depression or bowl, called by the natives Clach-rachen, near 

 which the sandstone is in a finely comminuted state, alternating with marls 

 and green earth. Looking back from the bay south of the Cock, the whole 

 thickness of the red sandstone series above described is seen at one view ; 

 the lowest beds of it terminate in a very coarse conglomerate alternating 



* The above sketch may serve as an introduction to the matter contained in the next section 

 of this paper. For more perfect details respecting the general structure of the Isle of Arran, we 

 must refer to the " Description of the Western Islands of Scotland," by Dr. MacCulloch. 



t This and the other Celtic words made use of in the present memoir are written as they are 

 pronounced by the islanders. 



