86 Renews— Geological Survey of Scotland — 



sj'stem of deformation, they have again suffered a repetition of the 

 process more than once. They consequently represent secondary 

 and tertiary, perhaps even quaternary, structures, probably due to 

 mechanical movements with accompanying recrystallization. The 

 regional metamorphism thus produced is not uniformly distributed, 

 but seems to increase in intensity both from the south-east and 

 north-west towards a nearly central line, ranging about north-east 

 and south-west, which is an anticline of the foliation. It has not 

 been traced to any intrusion of igneous rock, and is so general and 

 diffused that it can hai'dly be regarded as in any sense a contact 

 phenomenon. Where intrusive masses occur in the district they 

 have given rise to their own accompanying alteration, quite apart 

 from the general metamorphism of the whole area. These in- 

 teresting and complicated structures, so well displayed in Cowal, 

 are fully discussed in the present Memoir." 



The Director-General further observes that "Mr. Clough, having 

 mapped by far the largest part of the whole district, has had general 

 charge of the Memoir, which is mainly written by him." 



The extreme length of the district in question, from Ardlamont 

 Point on the south-west to the granite edge in a north-easterly 

 direction, is about 44 miles; with a breadth of about 18 miles from 

 Toward Point on the Firth of Clyde to Otter Beacon on Loch Fine. 

 The country is mountainous, though the elevations nowhere quite 

 attain 3,000 feet, and may be said to decrease rather uniformly towards 

 the south-west. By far the larger portion of the area is occupied by 

 metamorphic rocks. Subjoined is a list of these, not to be regarded 

 as representing a stratigraphical sequence. 

 Schists probably of Sedimentary Origin : — 



Phyllites, including the two series of Dunoon and Ardrisliaig, whicli consist 

 of phyllites and thin limestones, mixed in the first series with schistose 

 grits and in the second with quartzite schists. 



Schistose grits and greywackes. 



Quartzite schist or quartz schist. 



Albite schist. 



Garnetiferous mica schist. 



Graphite schist. 



Schistose limestones on various horizons, including the Loch Tay limestone. 



Mica schist. Areas coloured thus in the maps may also include unseparated 

 albite schists, sheared grits and greywackes, and phyllites. 



Green beds : chlorite -epidote schists. The group lines may include some 

 mica schists and schistose greywackes. 

 Igneous Eocks : — 



Epidiorites, hornblende and chlorite schists, serpentine. 



Besides the above a number of unfoliated igneous rocks occur 

 intrusive in the schists. 



The age of the schists, even in relation to each other, is not 

 certainly known, but the different bands are seen to traverse the region 

 in a north-east and south-west direction. The intimate structure 

 of the rocks is described with much detail. Amongst the physical 

 features of the more quartzose beds may be noted the occurrence of 

 pebbles, mainly of quartz, felspar, or clay-slate. These pebbles have 

 been subjected to a stretching action, which is supposed to have 



