﻿I860.] 



JAMIESOU'. S.W. HIGHLANDS. 



141 



in huge parallel masses running from S.W. to N.E. ; and to such an 

 extent are they developed in many places, as quite to overwhelm 

 the associated strata. From the fact of their being thus inter- 

 stratified with the slates and grits, Macculloch seems to have re- 

 garded them all as aqueous sedimentary masses ; for he has inserted 

 no trap or igneous rock in his map where they occur, and has 

 described them as a mere variety of chlorite-schist (see ' "Western 

 Isles,' vol. ii. p. 290). They are the typical beds of his " chlorite- 

 series," forming, as he says, nearly three-fourths of it ; and it is from 

 them tbat he has bestowed the name on the group, — quartz-rock 

 being ranked next in quantity. 



I was unable, however, to perceive any character wbereby they 

 could be distinguished from other greenstones : for they seem to be, 

 for the most part, composed of felspar and hornblende, and have 

 a massive form and crystalline structure like syenite or granite ; 

 they may also be occasionally observed resting on the upturned 

 edges of the sedimentary strata ; and finally, what seemed to me a 

 conclusive character, they have in many places exerted a powerful 

 metamorphic action on the adjoining strata. On the other hand, it 

 is difiicult to conceive how they could be of an eruptive nature, or 

 be injected among the stratified beds posterior to their formation 

 without deranging the disposition of these to a far greater degree 

 than they have done : and, what is even still more singular, there 

 are many huge masses which seem to have exerted no metamorphic 

 effect whatever on the adjoining beds of grit, which display the 

 water-worn grains of quartz in a perfectly similar condition to 

 those of Bute, where no such greenstone is near them. 



I have already mentioned that great quantities of greenstone come 

 out between the strata along the west shore of Loch Fyne, between 

 Barmore and Loch Gilp. One of these, near a place marked Mil- 

 more on the Admiralty Chart, is about sixty yards broad, and has 

 affected the quartz-strata on both sides, crumpling them up into 

 strongly wrinkled and corrugated masses, whose original greyish- 

 white colour has been changed into various hues of purple, red, and 

 yellow; and there are many segregations of vein-quartz, together 

 with streaks of a red colour strongly impregnated with iron-ore. 

 Their granular texture is also effaced, and they have become com- 

 pact and close-grained, like hornstone. The lamination and strati- 

 fication are in some places obliterated, and the rock traversed by 

 numerous fissures. At another spot, near Erins, I observed some 

 wedge-shaped masses of greenstone proceeding from the main body 

 and intruding amongst the quartz, where they thinned out into ten- 

 dril-like streaks. Near Meal Dhu Point another bed of greenstone, 

 30 or 40 yards thick, is seen coming out between the quartz- 

 strata, and powerfully affecting them on both sides to a distance of 

 about 20 yards. The stratified rock is crumpled up, loses its ordi- 

 nary pale greenish-grey hue, and assumes a variegated colour of 

 red, ochrey-yellow, green, and brown, irregularly mingled ; while 

 the lamination is in many places quite obliterated, and ravelled 

 veins of quartz ramify through it. Masses of the rock are con- 



