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CHAPTER III
STRATIGRAPHY
GENERAL STATEMENT

Information available on some parts of the geological column in north-
eastern British Columbia is much more complete than on others. That
acquired on the Proterozoic and Paleozoic formations is, for example,
based mainly on the section exposed along the Alaska Highway west of
Fort Nelson and through the Rocky Mountains. Elsewhere little is known
of these formations.

The Triassic, on the other hand, has been more thoroughly investigated
than any other system in northeastern British Columbia and in places has
been studied in great detail. The faunal zoning has been carried a long
way toward completion.

The Jurassic, Fernie group has received little attention to date, whereas
the upper part of the succeeding Bullhead group, because it contains coal
seams of commercial value, has been carefully examined at some locali-
ties. The lower part of. this group, however, should receive much more
attention than it has from stratigraphers.

The formations and faunal zones of the Lower Cretaceous, Fort St.
John group are now fairly well known, and are used by geologists engaged in
mapping. More time could, nevertheless, be profitably devoted to acquiring
additional information on the faunal zoning of this group.

The Upper Cretaceous, Dunvegan formation is now fairly well known
and can be recognized with the aid of its characteristic fossils. ‘The succeed-
ing Smoky group can also be identified by its faunas in northeastern
British Columbia, but it has not been studied at many localities and, in
places, appears to contain more sandstone than in the type area farther
east, in Smoky River Valley.

Some non-marine deposits of later Upper Cretaceous age, including
those of the Wapiti group, apparently occur in the eastern part of the area
covered by this report, but they have had little attention.

A few deposits of late Cretaceous or Paleocene age are known, in-
cluding the Sifton formation in the Rocky Mountain Trench. Tertiary
lignite occurs in the north. Little is known, however, of Tertiary beds
later than the Paleocene. Possibly some have been misidentified and
mapped as Late Cretaceous or Paleocene.

____ Rocks of the Cassiar batholith, the only intrusions of appreciable size
in the area, occupy part of the northwest corner, west of the trench.

A generalized table of formations follows ; more detailed tables will be
presented at intervals through this chapter.