Revieivs — Geological Survey of Scotland. 321 



Mr. Seymour. While the field-work was in progress petrographical 

 notes on various rocks from this area were also supplied by Mr. Teall, 

 F.R.S., Dr. Hatch, Professor Watts, Professor Grenville Cole, and 

 Dr. Flett. 



Considerably more than one-half (about five-eighths) of the area 

 of this Sheet is occupied by sea, the Firth of Clyde and its branches, 

 and the land amounts to only about 161 square miles. The land 

 area belongs to three different counties, and consists of no less than 

 nine separate portions, seven of them being islands or parts of 

 islands, and the other two belonging to the mainland. 



In the north-west corner of the map is a small portion (about 

 13 square miles) of the peninsula of Kintyre in the neighbourhood of 

 Skipness, Argyllshire. On the eastern border is a somewhat larger 

 area (about 16 square miles), part of the county of Ayr. It embraces 

 a strip of coast-land stretching from Largs to near Ardrossan, 

 together with the Horse Island opposite to its southern end. The 

 remaining portions belong to the county of Bute. Near the northern 

 edge of the map occur four of these — the southern parts of the 

 islands of Bute and Inchmarnock, the whole of the Little Cumbrae, 

 and neai'ly all of the Great Cumbrae. The largest land mass is the 

 northern portion of Arran, nearly three-quarters of the whole area; 

 and the northern end of Holy Island, which closes in Lamlash Bay, 

 completes the list. The extent of coastline in the Sheet is about 

 91 miles. 



Physical Features. — Naturally, from the small size of the separate 

 portions of land, there can be no large streams, but some of the 

 ground rises to a great height, especially in the Isle of Arran. The 

 Kintyre portion is an undulating tableland rising rapidly from the 

 sea-level to a height of 500 or 600 feet, and the highest point is 

 Cruach-an t-Samhlaidh, which reaches to 849 feet above the sea. 

 This area is drained by the Claonaig Water and the Skipness Water. 

 Inchmarnock is a low rocky island of less than 200 feet in elevation. 

 The western side of Bute rises to 279 feet above the sea. Birgidale 

 Butts is 400 feet above the sea. In South Bute the highest points are 

 Suidhe Chatain (517 feet) and Tor Mor (585 feet) near Glencallum. 

 The Great Cumbrae resembles Bute to the north of Kilchattan, and 

 rises to a height of 417 feet above the sea. Some intrusive igneous 

 masses, however, diversify its surface considerably. The Little 

 Cumbrae, rising to 409 feet, is rocky like South Bute, and has 

 a series of gently sloping terraces. On the Ayrshire side is the 

 rocky promontory of Portincross, 456 feet above the sea ; much of 

 the border of the Sheet is over 800 feet and at one place exceeds 

 1,000 feet in height. 



The tine peaks of the northern granite mountains, with their 

 deep-cut glens, are the dominant feature of the scenery of Arran. 

 These are contained within a circular area, about 8 miles by 7 

 across. All the principal streams take their rise in this mass or 

 from a smaller area on the southern edge of the sheet. Some of 

 the chief hills are Ard Bheinn (1,676 feet), A'Chruach (1,679 feet), 

 and Beinn Breach (1,649 feet). Nearly all the highest hills are 



DECADE IV. — VOL. X. NO. VII. 21 



