File:The Quarterly journal of the Geological Society of London (12645725615).jpg

188
PKOCEEDLNTGS OF THE GEOLOGICAL SOCIETY.
division -planes, which dip at 60° to S. 43° W. These rocks generally
weather to a dark rusty brown, probably from containing the prot-
oxide of iron. Soon after, the same rocks dip at 60° to N. 27° W.,
again on the foliation of the slate, but in a few yards fall to 35°, N.
27° W., from a curve in the beds. The next acclivity is a fine-
grained mica-slate with a veined aspect, from the folia being arranged
in curved layers. The dip here is still low (30° to N". 17° W.), but
soon rises to 65°, N. 12° W., in a grey mica-slate full of quartz-veins.
This rock continues to the summit of the hill, where the dip is 55°
N. 17° W., and a nearly similar dip appears in the rugged precipice
along the ridge to the north. Other division-planes, dipping 70°, S.
50° W., are seen in these cliffs ; and a series of ridges and hollows,
like the outcrop of beds, run N. 50° W. across the top of the hill.
The rock there is still a light-grey mica-slate, with small garnets
rarely disseminated through it.
s.
Fig. 5. — Section of Ben Lecli.

• e
  

a. Red Conglomerate.
b. Clay-slate.

\ \c

c. Mica-slate.
d. Greenstone.
e. Felspar-porphyry.
On descending the mountain on the north-east towards the top of
the great corrie that opens up from Loch Lubnaig, the mica-slate
passes into a coarse granular rock, full of rounded grains of quartz,
and almost like a greywacke, but still distinctly foliated. This is
again one of those transition-forms that so clearly illustrate the me-
tamorphic character of these rocks. The dip of these beds is 45° to
N. 18° E. ; but other planes dip at 67° to S. 38° W., and thus ap-
proximately parallel to the second set of division-planes already men-
tioned. It is, however, curious that these coarse-grained greywaeke-
like beds, both here and in other places, do not coincide in dip with
the slates or finer beds near them. Still lower on the mountain,
towards the south, mica-slate again appears, dipping 70° to N. 40° E.
Below it there is an irregular vein or mass of light-grey greenstone
decomposing in globular concretions, and probably the continuation of
the vein near Ardchullarie on the other side of Loch Lubnaig. Still
lower, a veryquartzose mica-slate,in thin beds, dips at 70° to N.27°W.
The stream continues to flow over irregular beds of mica-slate, in some
places much bent and contorted, and dipping E. at 10° to 30°, in other
places more regularly at 65° to N. 10° W. Near the foot of the
corrie the stream forms a series of picturesque linns over the ledges
of the fine-grained mica-slates, which dip at 70°-80° to N. 30°-40° W.