n8 Geological Notes from Arr an. [Sess. 



II.— GEOLOGICAL NOTES FROM ABBAN 



By Mr T. CUTHBERT DAY, F.C.S. 



{Read Dec. 26, 1894.) 



I daresay most of the members of this Society have some time 

 or other visited the island of Arran. Such a lovely spot cannot 

 fail to attract many visitors in the summer, especially as the 

 place is within easy reach. I only propose to-night to lay before 

 you a few geological observations made during a fortnight's stay 

 in Arran, and to exhibit some specimens of various rocks and 

 fossils collected at the same time. To all people proposing a 

 geological visit to the island I would recommend a perusal of 

 Bryce's book on Arran. Mr Bryce spent many years in the 

 place, and mastered the geological details with much energy and 

 perseverance. His book is divided, for convenience, into a 

 series of very interesting excursions, in which he points out 

 what to look for and where to find it. It is very evident that 

 Mr Bryce was a man of great endurance, for I found, when 

 trying to carry out his directions, that I could not get over 

 half the ground or get through anything like the amount of 

 work which he gives for a day's excursion. I must acknow- 

 ledge, however, that without his guidance I should not have 

 been able to see one-fourth part of the interesting details 

 which actually came under my notice. 



Geologically, Arran may be divided into two districts of 

 very different character by a line drawn from Brodick Bay in 

 the east to Dougrie in the west. North of that line we have 

 metamorphic rocks of a slaty nature, which occupy the coast-line 

 on the west and for about 1 J mile inland ; they also occur 

 to the east, but are separated from the sea by a narrow margin 

 of Old Eed Sandstone, and rocks of carboniferous age. They 

 also follow in a narrow band the line drawn from Brodick 

 Bay to Dougrie. Inside this belt of metamorphic rocks there 

 occurs an immense intrusion of granite which makes up the 

 bulk of the northern part of Arran. It is to the denudation 

 of this great granite mass that we owe the picturesque assem- 

 blage of rugged heights which characterise this portion of the 



