t 11
wide, forms a protrusion in the line of the cliff, traversing; the general rock, and proje
ctin g towards Kotzebue’s Sound. H e re it forms the rock first exposed in tbe cliff to
the south of the neck, producing four perpendicular and contiguous promontories, separated
from each other by small receding bays, and presenting a white and blue striped
stratification, with a dip of not more than 5®. The upper part of this lime-stone contains
iron pyrites, and has cavities filled with chlorite. The lower strata are more abundantly
intermixed with micaceous schistus, containing compact actynolite and flat prisms of
glassy actynolite, crystals of" tourmaline, and variously-formed crystals of iron pyrites.
The quartz in some places assumes tbe colour of topaz. Garnets occur in the mica
schist, and earthy chlorite is found in frequent small masses, chiefly investing quartz.
The iron pyrites in one place becomes predominant, and composes a bed, which does
not appear to be continued to any distance.
In one of these promontories, a deep and capacious cavern would afford shelter,
and may be a place of retreat for the natives, tbe foxes or the wolves.
Th e western side of Choris Peninsula is mostly composed of mica-slate rock, and
contains veins of quartz and felspar, with imbedded crystals of schorl, garnets, hornblende,
and" calcareous spar.
The Island of Chamisso, three or four miles in circumference, has rocky cliffs exposed
on all sides except to the east, where a gradual ascent conducts from the low
sandy point to the top. In its centre, a mound of bare rock constitutes the highest
p a rt; and towards the southern side of it, there is an appearance as if a circular pavement
of stones had been laid by the hand of man.
The general rock of this island is mica slate passing into flinty slate, and on the
north and south-west into gneiss. The strata rise at an angle of about 60° ou the northern
side. The imbedded minerals are garnets, schorl, and chlorite ; in the veins are
hornblende, quartz, felspar, and horn-stone. About seven miles east of Chamisso
Island, the cliffs at Eschscholtz Bluff are formed of a chlorite slate containing iron
pyrites. This rock constitutes an essential part of the formation for several miles south-
westward along that coast ; it contains numerous small garnets, and passes into, and
alternates with, mica slate and clay slate. The veins and imbedded minerals are
quartz, calcareous spar, chlorite, earthy felspar, crystals of tourmaline, garnets, &c.
Beds of blue and white primitive lime-stone, of slaty structure, cut the cliff a little,
inside East-spot station ; they dip at a very great angle to the westward.
Much of the coast of Kotzebue’s Sound, on the west of Cape Deceit, is composed
of dark blue slate, and slaty lime-stone having its layers separated by mica slate. On
tbe sooth coast of the Bay of Good Hope, the shore continues varied by cliffs of moderate
height and sloping declivities, for the distance of eight miles to tbe north-west,
apparently of the same formation, when it assumes a totally different aspect, being hollowed
out by numerous small bays separated by projecting points. The whole is low,
and the land rises up by gradual slopes covered with soil and vegetation. These low
projecting points are thickly strewed with large masses, partly of vesicular, partly of
compact lava containing olivine. Some of these blocks extend into the sea, others are
171
imbedded in the sandy soil of the beach, but many are insulated and exposed. The
empty cavities in some of them are as large as a man’s fist. The sand of the beach
partakes of the black and volcanic nature of these blocks, and so continues to Cape
Espenberg, where the large stones are no longer seen. These large and numerous
blocks, collected chiefly on the jutting points, must have been conveyed there by some
grand convulsion of nature, from a very considerable distance. No volcanic formation
is to be seen in the vicinity.—C.
C A P E T H O M S O N .
Remarks on the Stratification o f Cape Thomson, in lat. 67® 6' N ., long. 165® 45' W.
A section of this part of the north-west coast of America is given in plate I I .
Geology, from a map by Lieutenant Belcher. The summit of the northernmost cape (A)
is composed of carboniferous lime-stone, abounding with organic remains similar to those
of the lime-stone of Derbyshire. I t is also traversed by veins of chert of a blackish
cast, varying in thickness from six inches to two feet. I t here dips a t an angle of 10° to
the westward, and is succeeded, about half way down the cliff, by blue and black argillaceous
shale, with which it alternates in strata of six or eight feet in thickness; and
at about two-thirds down to the base, shale alone occupies the cliff, and becomes
abundant in organic remains; it is occasionally interstratified by lijne-stone, and much
contorted. This contortion is so great as to form two regular arches; the beds at the
lowest part are so much bent as to be doubled back on themselves. A t this point of
greatest contortion, they are cut off by a gap, where a stream (which must be very
powerful during the thaws in the earlier part of the season) had destroyed the continuity,
but still left sufficient to trace the connexion with the east side of the stream,
where the shale ceases to be contorted. Here, as we ascend the cliff B, we find the
lime-stone and chert resumed in rectilinear strata, dipping at an angle of 150® to the
westward. A t the east base of B, beneath the lime-stone, there is a recurrence of contorted
beds of shale, similar to those at the base of A, but more abundant iu veins ot
calcareous spar, pyrites, balls of septaria, and compact lime-stone containing tubiporite,
encrinite, &c.
A t the end of the bay, the lime-stone again commenced, of nearly the same character
as A ; the chert, however, assuming a greyish cast, end containing organic remains in
profusion; and under nearly the same circumstances as at A, the slaty shale underlaid
the lime-stone, but was covered in some places by a saline efflorescence (of sulphate of
lime), proceeding apparently from the decomposition of iron pyrites. Many of the
pieces contained crystals of carbonate of lime and selenite. Some chert which had
fallen from tbe centre of the cliff, I found loaded with layers of shells (chiefly bivalves).
Tbe chert appears to be the same as that from which the natives make their arrowheads
; and with the assistance of a small piece of bone, slices of it are easily reduced
to form; the manner in which they work it shows their acquaintance with the flat
conchoidal fracture, of which they take advantage. The height of the cliff A, which is
the highest of the two, is about 400 feet.