﻿I860.] 



JAMIESON S.W. HIGHLANDS. 



139 



Meal Dhii Point, the general character being a sort of granular 

 quartz-rock with little mica. Several large masses of greenstone 

 come out between the beds, and have crumpled them up, and in some 

 cases much altered their mineral texture, but do not seem to derange 

 the succession of the main body of the strata. At Meal Dhu Point, 

 or Strondoir, the rock assumes more mica, and continues to be mostly 

 micaceous with occasional beds of a more quartzy nature on to In- 

 verneil, where seams of green slate begin to show themselves and 

 become more and more numerous until they finally give the character 

 to the whole ; and from Ardrishaig to Loch-Gilphead the rock all 

 consists of the thin-bedded green slates, much traversed by green- 

 stone, but dipping constantly to N.W. at low angles. Notwith- 

 standing the prevalence of these greenstones all along the shore here, 

 the passage of the lower grits into the base of the slate -series is 

 clearly indicated ; and some of the finely laminated green arenaceous 

 layers noticed near Kildavannan Point occur also in the correspond- 

 ing part of the section. 



Finding, however, no sections along the Crinan Canal to show the 

 upper part of the slates, I betook myself to the ridge of Cruach Lussa 

 (the highest hill in North Knapdale — according to the Admiralty 

 Chart 1530 feet), lying between Loch Fyne and Loch Swen, where I 

 found the passage of the slates into the upper grits well manifested 

 in the south-eastern flank of that mountain. 



The base of the hill is here formed of a great thickness of these 

 finely laminated greenish slates, dipping N.W., at a high angle, into 

 the interior of the ridge ; and as I ascended I found them pass up 

 into greenish grits, with several thick masses of bedded greenstone. 

 These appear to form all the upper part of the hill ; but subordinate 

 slaty seams occur here and there, and one such finely laminated bed 

 passes over the very summit, enclosed between beds of grit and 

 greenstone. The N.W. brow of the hill shows thick strata of coarse 

 gravelly grit, perfectly identical with those in the upper grits of Bute, 

 and showing the same water- worn grains of bluish-hyaline and grey 

 quartz, of the size of peas or beans, — these beds all dipping to N. W. 

 at a very steep angle, accompanied by enormous masses of bedded 

 greenstone, which range from S.W. to N.E. for miles, quite con- 

 formably to the strata. 



Between Cruach Lussa and the Crinan Canal there is a barren 

 upland tract studded with tarns or little mountain-lochs, several of 

 which have been converted into reservoirs for the service of the 

 canal. This region is highly interesting in a geological point of 

 view, much of the rock being exposed, and showing great parallel 

 ridges of greenstone running along between thick beds of grit, with 

 some intercalated seams of slate and bluish limestone. At least 

 two beds of limestone occur in these upper grits here, but neither 

 of them so thick as that at Otter. They contain a good deal of sand, 

 and seem well adapted for the preservation of fossils ; and, although 

 I failed to find in them the slightest trace of organic life, I cannot 

 but think such will yet be found. There are also several finely 

 laminated schistose or slaty beds ; but these arc seen to be clearly 



