﻿136 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Dec. 19, 



boat-quay, in the Kyles of Bute. There in the brow of a large hill 

 called Ben Y-Happel, whose height is probably somewhere about 

 1500 feet, the folding over of the strata is distinctly seen ; and from 

 its summit I could trace the same anticlinal axis ranging away for 

 a long distance in a direction about N. 33° E. The lowermost strata 

 brought up in this anticlinal fold, as displayed here and at the north 

 end of Cantyre, where also I examined them, consist of hard rugged 

 masses, much wrinkled and contorted, composed chiefly of quartz and 

 mica — although felspar is also to be found, but forming in most places 

 only a small proportion of the rock. Portions would be correctly 

 termed gneiss, even in the strict definition of that term ; other por- 

 tions are more of the nature of mica-schist, and some of quartz- 

 rock ; while a greenish substance, probably chlorite, is often added 

 to the whole, giving its hue to the rock. The colour, however, 

 varies from pale greenish-grey to reddish-brown ; and I observed 

 small glancing octahedral crystals of iron-ore in various places, both 

 near the Kyles of Bute and in Cantyre. Notwithstanding the me- 

 tamorphic aspect of these lower rocks, their original arenaceous cha- 

 racter is in many parts still apparent, — thick beds, finely laminated, 

 containing the same water- worn particles of blue and grey quartz 

 as are found throughout the whole series of both upper and lower 

 grits, being met with in various places, enclosed amongst others in 

 which the lines of deposition are confused and obliterated. But the 

 pervading feature of the rocks all about this anticlinal axis is their 

 highly corrugated and contorted aspect, with numerous segregations 

 of quartz. This axis, I am inclined to think, will be found to run 

 through the country for a very long distance, passing probably by 

 the head of Loch Lomond on to the valley of the Tay, where I ob- 

 served it on the same line of strike, at Aberfeldy, in 1859. Similar 

 masses of hard rugged gneiss and mica-schist rise up there in a 

 gentle dome-shaped curve, and are seen on both sides of the river, 

 more especially in the rocky face of "Weeni Craig, throwing off heavy 

 micaceous strata to S.E. and X.AV. 



From this ridge of Ben Y-Happel, if we proceed (south-east- 

 ward) across the Kyles through Bute, we pass over a continuous 

 series of rocks, following each other in quite conformable succession, 

 and all dipping steadily to S.E. , until we come to the Old Bed Sand- 

 stone in the neighbour-hood of Rothesay. In no part of Bute, 

 neither on the east side nor on the west, where I followed the whole 

 line of coast to the north of Scalpsie Bay, nor in the interior, did I 

 meet with a reversed or N.W. dip. If again we turn our faces in 

 the opposite direction (to the N.W.), towards Loch Fyne, we pass 

 over a similar series, all conformable and dipping in like manner to 

 the N.W. 



§ 3. Taking the Bute or south-eastern section first (which is a 

 veiy satisfactory one, as the rocks are disposed with great regularity, 

 without any quantity of disturbing masses of an eruptive nature), 

 it will be found that after leaving the neighbourhood of the anti- 

 clinal axis the strata become gradually less and less contorted, failing 

 into regular parallel beds as we proceed across them ; the quantity of 



