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western area belong to two bands that near Marmot river are separated
by a band of voleanic rock. The southern sedimentary band is in con-
tact with Coast Range intrusives along its southwest edge and is cut off
by these intrusives before reaching Portland canal. The second band
strikes northward, widens in the vicinity of Bitter and Glacier creeks, and
eventually narrows and terminates in the northern part of Bear River
district.

The prevailing dips in the southern band are northeasterly and the
sediments apparently dip under the adjacent voleanic rocks to reappear
and form the northern sedimentary band. The rocks in this band are
harder than the other sediments in the area, due, probably, to thermal
metamorphism resulting from batholithic invasion. 'The sediments of the
southern end of the northern band le in a sharp anticline slightly over-
turned to the west and plunging under the volcanic rocks to the south.
Farther north overturning is not marked but the anticline is asymmetric.
Still farther north the anticline flattens and the band broadens consider-
ably. In the broad part the general dip of the strata in the western
part of the band is 35 degrees westward, the main anticline becomes two
anticlines with a shallow central syneline, and the whole is complicated
by minor folds. North of Bear river the sediments lie in a narrow, sharply
folded anticline and plunge under voleanic rocks. At many places along
the western edge of the northern band the relationship to the overlying
- volcanic rocks is clearly visible. The sediments underlie them conform-
ably and there is a transition zone characterized by interbedding of sedi-
mentary and volcanic rocks. Dips are rarely seen in the volcanic rocks,
but wherever observed they indicated concordance between the voleanics
and sediments.

The sedimentary rocks of Marmot and Bear River districts are chiefly
black argillites. In most places the beds are thick and blocky, but in some
places, particularly at the headwaters of Kate Ryan creek and in the
vicinity of Bromley glacier, the beds are thin and consist of black argil-
lite and light-coloured quartzite in layers 1 to 2 inches thick. Light grey
limestone is present in several places but usually as thin, discontinuous
beds, although lenses of limestone 100 feet thick are known. Tuffs, brec-
cias, and probably lava flows occur at several places. Locally, as on Kate
Ryan creek and along Bitter creek, the rocks have been severely sheared
and converted to micaceous schists. The upper 500 feet of the sedimentary
division is calcareous, contains several beds of limestone, and holds num-
erous interbeds of tuffaceous rocks. Tuffs also occur lower in the section
but probably not below the middle. Banded argillite-quartzite rocks occur
from the middle of the division downward and most of the lower part con-
sists of argillite and banded argillite and quartzite. The coarser sediments
contain pebbles of tuff, cherty argillite, and crystalline igneous rock. On
Kate Ryan creek the sediments are at least 3,000 feet thick.

North of Bear river the country is underlain by voleanic rocks, but for
several miles along the upper reaches of American creek black, calcareous
argillites and argillaceous limestones outcrop on the lower slopes of the
valley up to 500 feet above the valley floor. To the north they end a
short distance south of the divide at the head of American creek. The
higher slopes on either side of the valley are occupied by volcanic rocks