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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



[Dec. 19, 



of 538 feet. These grits cover a space at least a mile broad in the 

 middle of the island ; and as they dip at high angles to the S.E., they 

 mnst evidently be of considerable thickness. They are the uppermost 

 of the old rocks as displayed in Bute, being bordered by the Old Red 

 Sandstone to the south along the hollow of Loch Fadd and Loch 

 Quien to Scalpsie Bay. The actual meeting of the two formations, 

 however, is not seen, except for an insignificant space at Ardscalpsie 

 Point ; and a good deal of trap appears to oceur along the boundary. 

 These grits are not, I believe, the lower grits brought up by a 

 fault; for they follow the slates quite conformably, without, so far as 

 I observed, any trap coming up between them. They contain at 

 least one band of dark-blue slate, near their base, and also differ 

 somewhat from the lower grits in containing a greater prevalence of 

 coarse-grained gravelly layers. There maybe some fault at the N.E. 

 base of Barone Hill, where the ridge suddenly terminates ; for a 

 great trap-dyke crosses the island there in a N.W. direction, and, 

 traversing the slates, runs out to the shore a little to the south of 

 Ettrick Bay ; but whether there actually is a fault I could not 

 determine, owing to the nature of the ground. 



This Bate section, then, shows at its base a set of contorted micaceous 

 grits, followed by a great thickness of siliceous grit, above which 

 comes an extensive development of thin-bedded sediments or slates, 

 these slates being covered by a mass of grit containing at least one 

 seam of slate, and having more frequent beds of coarse gravelly tex- 

 ture than are met with in the lower grits. I observed no decided 

 bed of limestone in these old rocks of Bute, but found, deep down in 

 the lower grit, some beds which contained calcareous matter, effer- 

 vescing readily with nitric acid. 



§ 4. In descending from the anticlinal axis of Ben Y-Happel 

 towards Loch Eyne, I found ridge after ridge unfolding precisely the 

 same series of micaceous grits, indurated sand, and gravel that I had 

 examined in Bute, in a similar state of metamorphism, all follow- 

 ing each other conformably, and dipping steadily to the N.W. ; and 

 these grits continue all the way across to Otter, where there is a 

 thick bed of bluish limestone, forming a small wooded hill, and quar- 

 ried beside the Otter Inn. This limestone is covered by quartz-rock, 

 and rests upon micaceous grit, and may be traced for some distance 

 along its N.E. strike. I believe it is also found near Eilfinnan ; and 

 I heard of some other seams or bands of limestone in Cowal — one 

 somewhere near Ardlamont Point, which would be on the strike of 

 the calcareous grit that I observed in Bute. 



Again, in following the west shore of Loch Eyne from the neigh- 

 bom-hood of the anticlinal axis in Cantyre north to Loch-Gilphead, the 

 strata all have a general dip to the rT.W. I found, first the crumpled 

 coarse gneiss and mica-schist to the south of East Loch Tarbert, 

 gradually falling into more regular stratification towards Barmore, 

 near which a strong band of bluish limestone, quarried at Ashins, 

 and apparently the same as that of Otter, rims across to "West Loch 

 Tarbert. After passing Barmore the rock is very siliceous, and con- 

 tinues so all along the base of the lofty ridge of Sliabh Goil on to 



