File:The Quarterly journal of the Geological Society of London (12711418015).jpg

172
PROCEEDINGS OF THE GEOLOGICAL SOCIETY. .Jan. 31.
line of foliation. In the different beds of limestone I did not observe
any mica whatever.
(Case 8.) — On the other side of Christiansand, about five miles
from the town, west of Torresdale River, we have very extensive beds
of a white crystalline limestone, very similar to, and foliated like, the
last-mentioned. A section is seen in fig. 4, and represents a quarry
near the top of a mountain called Pusaasen.
Fig. 4. — Section of gneiss and limestone at Pusaasen Mountain,
near Christiansand, Norway.
a. Granitic gneiss ; not distinctly foliated.
b. Quartzose, brownish, foliated gneiss.
c, c. White, crystalline, foliated limestone (about 15 feet exposed).
■r, x. Indeterminable broken and weathered mass, filling joint.
The section is taken about parallel to the strike, or 40°N."W.--S.E.
The strata incline towards the south, and dip at 15° S.W. At the
top of the section on the north side we have a considerable mass of
gneiss (a), without a grain (or nearly granite-gneiss), with no foliated
arrangement apparent, very quartzy, and containing but very little
mica. This abuts against a bed of very quartzy gneiss (Z.), where the
lines of the foliation give the appearance of its having been doubled
up. This gneiss contains numerous crystals of iron-pyrites in the
lines of foliation, and by their oxidation it has acquired a rust-brown
colour. Between these two gneiss rocks we have a joint filled up
with a broken, decomposed, and weathered mass (x), of undistin-
guishable character ; but below the whole is a large bed of white
crystalline limestone, foliated by lines of augite-crystals, precisely as
in the last case ; the foliation is here parallel to the upper and lower
surfaces, or the foliation, of the gneiss above it. About 15 feet of
the limestone bed is uncovered ; the lower 3 feet is coarser-grained
than the upper 12 feet. At a few spots mica is seen present, foliating
the limestone in a similar direction.
(Case 9.) — On the same side of the Torresdale River, and about