CHAPTER II
GENERAL GEOLOGY
INTRODUCTION

Portland Canal area lies along a part of the eastern margin of the
elongated body of the Coast Range intrusives which stretches northwestward
along the Pacific coast from near the southern boundary of British Colum-
bia to and into Yukon. In Portland Canal area the formations bordering
the intrusives on the east are Mesozoic sedimentary and volcanic rocks
and Tertiary lava. In previous reports dealing with parts of Portland
Canal area the Mesozoic was considered to consist of, in ascending order,
the Bitter Creek, Bear River, and Nass formations, and, perhaps youngest
of all, bodies of augite porphyrite. From evidence collected in Alice Arm
district, the writer concludes that the Bitter Creek and Nass formations
are parts of a single sedimentary series, and that the Bear River volcanics
and the augite porphyrite are products of local volcanic outbursts.

As the sedimentary rocks appear to be one series, neither of the two
names Nass or Bitter Creek will serve for this formation. The term Bear
River could perhaps be retained for all the volcanic rocks, but the name
Hazelton group, used first in the vicinity of Hazelton to designate all the
Mesozoic rocks older than the Coast Range intrusives, can be used with
more assurance for the sediments and volcanics combined.

Table of Formations

Modemiys 26). sesch a eee Recent and Pleistocene......|/Gravel, sand, silt, varved clay, marine
or estuarine clay, boulder clay, glacial
rut
ARVET CLITA WAT ees thee per cheer iis] MSE cor eae Ra Cet in = ean Basaltic lava flows
Harly Cretaceons to Juras=| oie via victe gic ees se teres coeys Dykes
sic ——
Coast Range intrusives...... Granodiorite
Jurassic and perhaps in part|Hazelton group............../Argillite, quartzite, greywacke, lime-
Triassic and Early Cre- stone, tuffaceous sediment, breccia,
taceous tuff, augite porphyrite, felsite, amphi-

bolite, gabbro

HAZELTON GROUP

The volcanic rocks of Portland Canal area are similar in age and
lithological character to those of the Porphyrite group of Dawson and the
Hazelton group of Leach. The name Porphyrite group was introduced by