109

none is sufficiently complete for identification. The best is seemingly a
Viburnum .... There is a single, small, poorly preserved fragment of a
fern, again not certainly identifiable although comparable to Asplenium?
coloradoense Knowlton or to Aspleniwm? magnum Knowlton. The bulk
of the collection consists of twigs of a Sequoia, probably belonging to the
same species as one recorded by Hollick from the Upper Cretaceous Chignik
formation of Alaska....... the best that may be stated is ‘Upper Cre-

taceous?’ A Paleocene or Eocene age is a possibility’ (See Hedley and
Holland, 1941).

Roots (1948) suggests that the Sifton formation may be ‘‘regarded as
_ a part, probably an upper part, of the Sustut group of areas to the West’’.
The formation is of some interest in view of its composition, age, position
on the floor of the trench, and its structural relations to adjacent forma-
tions. Its study may provide important evidence bearing on the history
and origin of the trench.

BEDS WITH EQUISETUM ARTICUM

Hage (1945) has suggested that some sandstones, shales, and conglo-
merates on Petitot River, about 5 miles above the canyon, are of Tertiary
age. They are not, however, mapped separately on the Lower Liard
River map nor on the map accompanying the present report, but are in-
cluded with the Upper Cretaceous formations.

Hage measured the following Petitot River section:

Top of Section Thickness

Shale, interbedded with fine-grained sandstone; contains plant

OVMAINIS Papp evayovcusscveusconsrstetehe iszete hale ekevobeecedapotniotorevetassiorstarsions 5-0
Conglomerate; chert and quartzite pebbles and coarse sandstone. 25-0
Shale, dark grey, and sandy shale; beds 10 to 12 inches thick... 21-0
Sandstone, medium-grained......... 2-0
Shalendarkereyseee nee eee 1-0
Sandstone, feldspathic, medium-grained 566 ee)
Shalemlightigreyseri ceteris tecterike ieee ette terietet-r-forar-i 1-0
Sandstone, fine-grained, thinly bedded............--.--+-.+-- 3-0
Bentonite, and streaks of carbonaceous matter.........-....-. 0-1
Shale, light and dark grey. .......... sees esse eee e eee e eee 6-3
Staley, RMR 75 3530 boo s00cb00b000000000000000990060050000000 1-0
Shale, fissile, dark grey...... 2... eeesee cece cece eect teens 10-0
LSOTIGIMIS BA Bad oe coon ed ee obs cobave ues capecusepenedGdE aa 0-05
Chines oanoucocs aon obbodbondondonoonoodoDED ude SdoOcKr 1-0

Aiaytall in@anessongaocouddaods opp0neopoUOm ED OuDO 83-45

Fossils from the top of this section were identified by W. A. Bell as tu-
berous rhizomes of Hquisetum arcticum Heer. Bell noted “that the species
occurs in Arctic Paleocene, and if the beds containing it on Petitot River are
actually Upper Cretaceous the range of the species must be extended
(from Hage, 1945).

Hage states that these ‘“‘beds are assigned tentatively to the Tertiary,
but, as definite proof of age is lacking and as field observations were limited
to a single outcrop, they have not been mapped separately from the late
Upper Cretaceous on the accompanying map.