EOCES OF THE NOETHEEN HIGHLANDS. 373 



Dolomite series is complete about a mile to the west, at Loch Mao- 

 lack Corry ; and it is also seen in both its members on Loch Em- 

 boli, at 25 miles distance. It is therefore highly improbable that 

 snch a rapid attenuation should occur between Loch Maolack and the 

 Balloch. 



(2) The dolomite at its junction with the " Upper " Quartzite is 

 crushed into an angular breccia for a distance of several feet, a 

 fact the significance of which it is needless to point out. 



(3) The quartzite which it is alleged to overlie contains bits of red 

 felspar, as in ordinary basement quartzite. 



(4) If there is no fault here, several hundreds, if not thousands, of 

 feet of gneiss have entirely thinned out within 100 yards. On the 

 precipitous slopes just above the dolomite to the east, we come to 

 massive gneiss (Logan Rock) rising in steep cliffs to about 1000 feet 

 above the Balloch (1500 feet), extending to the east in the tremen- 

 dous precipices which fall down from the peaks of Ben More, and, 

 in fact, forming the chief mass of that magnificent group of moun- 

 tains. As the bedding is vertical or very high, the thickness must 

 be considerable. Ex hypothesi the place of this gneiss is between 

 the Dolomite and the "Upper" Quartzite; yet, within a stone's 

 throw to the west, the gneiss is wanting ! Comment on such a fact 

 is superfluous. My full reading of this section, with an illustration 

 (fig. 6), will be hereafter given (p. 383). 



Section up Glen Gout (fig. 7, p. 391). 



I have shown that in the typical localities of Murchison the 

 so-called " Upper " Quartzite is composed of two members, "Seamy " 

 and " Annelidian," which precisely resemble the two divisions of the 

 " Lower " Quartzite. But it will possibly be urged that this 

 similarity is due to a repetition of similar conditions. This objection, 

 however, could hardly be made if in any place we found the 

 " Upper " Quartzite to include the chief members of the Assynt 

 series. Such a section actually occurs in Glen Coul. 



About a mile up the glen, we see that the " Logan Rock " is 

 overlain by quartzite, seamy, with red felspar bits. Leaving the 

 stream and ascending the slope to the north, we come to the Anne- 

 lidian Quartzite ; and just below the conspicuous peak formed by the 

 Caledonian, the Brown Flags occur in place, overlain by dolomite. 

 The quartzite is rather below its average thickness. The flags also 

 are attenuated ; but we can detect two varieties of the group, shales 

 and ferruginous dolomite, such as are seen at the mouth of the 

 glen, below the Hebridean. The dolomite is very thin, probably 

 under 20 feet. It is of the typical dark-grey type. The total 

 thickness of the Assynt rocks in this section I estimate at a little 

 under 250 feet. On the sea-loch, over a mile to the west, it may 

 reach 100 feet more ; but even here the Dolomite is, in some spots, 

 very thin or entirely wanting. The only difference between the 

 groups above and below the Hebridean is, that in the western section 

 the Flags and sometimes the Dolomite are much thicker. But that 



Q. J. G. S. No. 155. 2e 



