the unstratified and the stratified formations. The Barn itself is
a long, huge pile of alternating strata of mud, débris, and lavas,
similar to what has been already described, rising almost perpendicularly
to 2000 feet; the strata inclining 20° to the eastward, and
35° to the northward. Passing along in front of Longwood, over
Dead wood and Rupert’s Valley, to the ridge which separates the
latter from .Tames’ Valley, the upheaval is plainly recognised at a
point situated some little distance north of Sampson’s Battery, by
the sudden change in the inclination of the strata from about 6° to
8°, or 10°, and the presence of two very felspathic dikes, each
fifteen or twenty feet in thickness, which intersect the ridge in a
south-westerly direction ; one of these dikes, the material of which
may be fused at no very high temperature into a kind of coarse
black glass, can be traced across James’ Valley, passing above the
Military Hospital, and up the eastern side of the plateau which
supports the hill called High Knoll, a lateral volcanic cone
formed by lavas ejected through the fissure which this disturbing
force had caused. This cone has a height of its own of about 500
feet, while its entire altitude above the sea is 1903 feet. I t is composed
of very frothy, scummy lavas, tufas passing into breccias or
pudding-stones, mixed with ashes and cinders. Hone of the
lavas are compact, but sufficiently close in texture to form a good
building-stone easily worked with the chisel, hence “ High Knoll
stone” is much in request for the best style of building, including
the fortifications and other military works. Most of the lava is
however very scoriaceous, resembling a coarse kind of pumice-
stone, and bearing more recent marks of fire than any other rock
in the Island. The formation of the cone exhibits in a most
interesting and striking way the influence of the wind upon ejected
matter from a volcano. That side which immediately faces the
south-east trade wind is quite perpendicular, while the whole of the
ejected matter has been blown in the opposite direction and built
up three' sides of a most complete cone, with its slopes inclined
at angles of about 20° or 25°. I t is remarkable that the decomposition
of this High Knoll lava produces an ashy kind of soil, in
which few plants will grow and scarcely any thrive. ITpon the top
of this cone 1 picked up what appeared to be a lava internal cast of
a bivalve shell, about six inches in length, and very much resembling
unio sheppar dianus, or some similar species. I t is quite possible that