Notices of Memoirs — P. Macnair — Schists of S. Highlands. 567 



Ballantrae in Ayrshire. Two distinct volcanic platforms have been 

 found in the Old Eed Sandstone of the island. One set of basic 

 lavas is intercalated in the lower division on the west side of the 

 island, and another occurs in the upper division of the North Glen 

 Sannox. In addition to the volcanic series previously known in the 

 Lower Carboniferous rocks two others have been discovered in the 

 upper part of the formation. That the island was the seat of volcanic 

 activity in times still more recent is proved by the recognition of 

 a large volcanic vent in the Shiskin district, which must be of 

 post-Cretaceous age, as shown by some of the fragments it includes. 

 From these facts we conclude that the island has been the scene of 

 volcanic action at no less than seven different periods. 



Much has also been learned with regard to the distribution and 

 age of the various intrusive igneous rocks. Two masses of a some- 

 what intermediate character found in Glen Rosie and in Glen Sannox 

 are probably of Old Eed Sandstone age, but nearly the whole of the 

 varied igneous rocks of the island must now be assigned to the 

 Tertiary period, not excepting the well-known granite mass of 

 the northern part of the island. The finer granite which occupies 

 the interior of the nucleus has a tortuous boundary. It is clearly 

 intrusive in the coarse granite which surrounds it, but both belong 

 practically to the same period, as they have one and the same system 

 of jointing. 



The ring of granite, granophyre, and quartz diorite which sur- 

 rounds the large volcanic vent was previously little known, and 

 the other numerous and varied intrusive masses, both acid and 

 basic, which occur in the island were but poorly represented on 

 existing maps. 



VI. — On the Crystalline Schists of the Southern Highlands; 

 THEIR Physical Structure and Probable Manner of 

 Development. By Peter Macnair.^ 



rpHE area under notice is defined as that lying immediately to the 

 X north-west of the great boundary fault which crosses Scotland 

 from the Firth of Clyde to Stonehaven. An account is then given 

 of the various opinions that have been held concerning the structure 

 of this region since the time of Macculloch up to the present day. 

 The author then proceeds to show that the schist zones traverse this 

 region in roughly parallel bands, and described a series of sections 

 at right angles to the strike of the principal foliation of the area. 

 The following is a summary of the author's conclusions regarding 

 the stratigraphy, physical structure, and the manner of development 

 in this part of the Scottish Highlands : — 



1. The sedimentai-y schists of the Highlands proceeding from the 

 mai'gin inwards may be divided into the following zones : — Lower 

 Argillaceous zone, Lower Arenaceous zone, Loch Taj' Limestone 

 zone, Garnetiferous Schist zone, Upper Argillaceous zone, Upper 

 Arenaceous zone. Associated with these are schists of igneous 



1 Read before the British Association, Section C (Geology), Glasgow, Sept., 1901. 



