7

of Marmot and Bear River districts. East of Alice Arm district a broad
band of the sediments underlies the country at least as far east as Nass
river and extends north-northwest beyond the northern limit of Portland
Canal area.

South of Illiance river and south of the Theophilus igneous body, the
sediments dip about 30 degrees southward. East of the southern part of
the igneous body they have an average easterly dip of 20 degrees. North-
east of the Theophilus igneous body in the vicinity of Kinskuch lake, the
sediments dip in the main northeast at moderate to gentle angles. Farther
north the dips of the sediments are to the east or northeast.

The eastern part of the Theophilus igneous body consists in the main
of fragmental volcanic rocks in part water-sorted. They have for the most
part gentle dips, but the dip observations are not sufficiently numerous to
show that the fragmental igneous rocks are absolutely concordant with the
sediments to the east and northeast, and at the south end of the Theophilus
body the contact appears to be considerably steeper than the dip of the
sediments farther south. There seems to be no doubt, however, that the
eastern sediments overlie the Theophilus igneous body and where the vol-
canic rocks are stratified they appear to be concordant in strike and dip
with the overlying sediments. These sediments, therefore, appear to belong
to the upper part of the Hazelton group. East and southeast of Illiance
river and also northeast of the Theophilus body, they are mostly black
argillites with local interbeds of greywacke and argillaceous quartzite. The
argillites for the most part consist of fairly homogeneous beds 6 inches or
so thick that yield a talus consisting commonly of rectangular blocks.
Immediately south of Alice Arm the sediments are typically coarse grey-
wackes. These rocks appear to grade into the argillites a short distance
east but may underlie them. To the southwest the sediments are
mainly argillites. The rocks in. this vicinity, however, are near
the contact with the Coast Range intrusives and have been too greatly dis-
turbed by faults to make their position in the sedimentary series readily
determinable. The thickness of the sediments in the area south and east
of Alice Arm probably exceeds 3,000 feet.

The sedimentary band lying west of the Theophilus body and separ-
ating it from the Kitsault body is about 20 miles long north and south.
The sediments along the western edge of the Theophilus body dip for the
most part about 45 degrees eastward. On the western slopes of mount
Theophilus sediments and stratified voleanic rocks are interbedded through-
out a thickness of 1,500 feet and at the base of the Theophilus body dip
45 degrees east. The sediments of the upper part of this thickness where
interbedded with stratified tuffs are locally argillites, but in general are
coarser and not black. At the base of the interbedded rocks the sediments
are black argillites. Farther north on Dak river the sediments are largely
argillites and the transition from sediments below to volcanics above is
more abrupt, but locally there is some interbedding. At the western side of
the band of sediments in the vicinity of Dak river the strata are almost
horizontal. LeRoy mountain in the middle of the band and west of the head
of Dak river consists of quartzite and other sedimentary rock of similar
grain. These rocks do not show many features by which their attitude can