386 C. CALLAWAY ON THE NEWEK GNETSSIC 



and seamy quartzite being thrown over onto the Brown Flags, and, 

 perhaps, the Dolomite masked by the drift. 



Following the inverted quartzite to the north, and circling round 

 the north end of the hill to its eastern slope, we keep continually 

 upon quartzite ; so that it would seem as if the Hebridean were en- 

 closed in an overthrown fold of the quartzite, just as it is wrapped 

 in a fold of grit in Coniveall. The ground, however, is so obscure 

 that, without the key furnished by our previous studies, it would be 

 difficult to arrive at even a probable conclusion. 



D. The " Upper Limestone" non-existent. 



(a) The Dolomite repeated. 



The dolomite of Glen Coul and Ehie Cnoc, being a part of the 

 eastern outliers of the Assynt series, are, of course, merely the 

 ordinary dolomite repeated. 



(b) A part of the Caledonian Group. 



The crystalline limestones of Loch Ailsh were considered by Mur- 

 chison and his followers an upper limestone of the Quartzite series ; 

 but by Nicol they were regarded as the Assynt series metamorphosed 

 by contact with igneous masses. After devoting nearly a week to 

 the study of the ground, I arrived at the conclusion that these rocks 

 were a part of the Eastern Gneiss, and therefore of Archaean age. 



Prof. Heddle holds that these limestones are divisible into two 

 zones, separated by a band of " hornstone porphyry," which runs 

 along the western base of Cnoc Chaorinie (Chaoruinn). The lower, 

 which he considers a true marble, " apparently sweeps round to 

 the south of the hill Scounan." The upper, which he describes as 

 " not perfect in its metamorphism, and approaching in character 

 to a granular limestone," is continued on the strike to the north, 

 and, according to Murchison, " sweeps round to the east and north 

 of the mountain of Ben More, and extends up the valley of the 

 Cassley to the side of the Stack of Glen Coul." I will first discuss 

 the last statement. 



The limestone which is seen at the side of the high road east of 

 Loch Borrolan, near the turning to Ben More Lodge, can be traced 

 along the western face of Cnoc Chaorinie, up the eastern side of 

 Loch Ailsh, and on by Ben More Lodge to about a mile north of 

 Kinloch, a distance of nearly four miles. It tapers towards the 

 northern end, and disappears beneath an extensive deposit of boulder- 

 clay covered by bog. A little beyond, the " porphyry," which has 

 been flanking the limestone on the west, comes up to the Caledonian, 

 so as to cut out the limestone. I traversed the ground for miles to 

 the north, and found nothing but drift and bog between the eastern 

 gneiss and the quartzite of the Ben More massif. These facts, there- 

 fore, do not confirm Murchison's view. The ''limestone" near 

 Glen Coul, apparently the dolomite at Rhie Cnoc, is separated from 

 the Loch Ailsh series by several miles of covered ground ; so that no 



