EOCKS OE THE NOETHEEN HIGHLANDS.
371
" Logan Rock " of Glasven. — It is necessary here to anticipate a
part of our proposed discussion on this disputed rock. In the upper
part of Calda Burn the Quartzite rests upon gneiss. This rock is
massive and coarsely crystalline. Were there no theoretical reasons
to suggest a contrary conclusion, I think it would occur to no one
acquainted with the district that this was any thing but the ordinary
Hebridean, which appears in place a mile and a half to the west.
Many hand-specimens taken at random from both localities are quite
undistinguishable. With the exception of a thin capping of quartz-
ite, this gneiss forms the chief mass of Glasven (2541 feet). The
bedding is much contorted, but is, on the whole, towards the east.
According to the received view, this gneiss is conformably interca-
lated between the Dolomite and the " Upper " Quartzite. But in our
former section (fig. 2, p. 368), the quartzite is alleged to rest, and
does appear to rest, upon the dolomite. We are therefore asked to
believe that this great mass of gneiss has thinned out within 500
yards. Other difficulties will be pointed out further on.
Section from the west end of Ben Uarran to the high road
south of Inchnadamff (fig. 4).
This line runs parallel to Poulan-drein, at a distance of about 400
yards. Standing at the fall over the /SaZ^r^ZZa-quartzite in Poulan-
drein, and looking along the strike to the south-east, we can see the
Dolomite (upper section in fig. 3) rising up into the low ridge behind
the house called in the Ordnance Map Glenbain, and the beds can be
traced without a break between the two points, and on continuously
to the S.E., dipping steadily to the S.W., and forming the N.E. side
of the Stronchrubie syncline. At Glenbain the Dolomite is regularly
Fig. 4. — Section betiveen the west end of Ben Uarran and the high road south of
Loch Lnchnadamff. (Scale 3 inches to 1 mile.)
Ben
N.E. Uarran.
Talus.
Stronchrubie
syncline.
W.S.W.
underlain by the Brown Flags, just as on Poulan-drein, but with a
lower dip ; and to the south-east the Annelidian Quartzite comes in
conformably under the flags. Turning to the N.E., and ascending the
slopes of Ben Uarran, we pass outcrops of the same quartzite. Then
we find it rollover slightly to the N.E. and after a narrow interval
occupied by talus, we come again upon the Annelidian Quartzite almost
vertical. It is impossible to speak with certainty of what underlies