66

Feet
HOSSINLCHOUS “MeStON Ge ae ele a eg wesc Fee he Sah Ree
Blue-grey clay shale... .. . Bre Fhe Pee REM SS a ee
Thin-bedded, fossiliferous limestone. es Perth 6 Sats 8
Blue-green, clay shales, limestone bands swith. fossils. ee ig? cee AOS
Mimo pedged lMrEsStONnes TOSSING es. a Se ee et le ele ce es nes fie 8
Blue-green, clay shales .. .. . Sarai. eta eect t PAE TSE SEU Sateen eS 0 oe ee)
Sandstone, ripple-marks and worms. ae SEITEN as ee eae Pie Meurer oe) oe
Blue-green, clay shales, limestone bands with fossils... .. .. ... 90 aneroid
Thin-bedded limestone, shaly, argillaceous.. .. .. .. .. .. .+ ++ 25
Blue-green, clay shales, bottom not exposed. : :
6015

The limestone beds which form the chutes of Peace river are correlated with
some of the limestone bands in this section. The same horizon which is repre-
sented by the Alexandra Falls section is exposed in the walls of the canyon of the
Liard which are 200 to 400 feet high. These begin 25 miles above the mouth of
that river. Spirtfer disjunctus is one of the most abundant and characteristic
species found in this portion of the upper Devonian section which has been
called the Hay River shales and limestones in the Great Slave Lake district.
Beds corresponding to this horizon form the higher beds of the long ridge which
- separates Root river from the Mackenzie. They also outcrop 7 miles below
Wrigley on the west bank of the Mackenzie, a few miles below Norman on both
banks of the Mackenzie, near the mouth of Oil creek, and ‘at various other
localities. The top of the oil well 40 miles below Norman starts in beds of this
horizon.

The limestones and shales which outcrop along Athabaska and Clearwater
rivers appear to belong to the upper Devonian series but represent a very different
faunal and lithological facies from that shown in the sections to the west and
north. The outcrops of these beds which are exposed between Firebag river and
McMurray at frequent intervals show a number of low arches which are seldom
more than a few hundred yards across. The Tar sand or McMurray formation of
the Cretaceous overlies the Devonian beds along Athabaska and Clearwater rivers

Triassic

Limestones, sandstones, and shales carrying a marine Triassic fauna are
exposed on Liard and Peace rivers and on Pine River South. F. H. McLearn,}
who has made an examination of the section on: Peace river, states that dark
purple limestones, hardened sandstones, and shales outcrop at Parle-pas rapid
and on the south bank of the Peace 2 miles below the mouth of Ottertail
river. About 4 miles above Fish creek on the north bank the strata are steeply
inclined to the west. At the mouth of Twentymile creek there is a second and
probably a lower Triassic horizon, the rocks consisting of limestones, sandstone,
and shale. The entire series is quite thick and is probably all of marine origin.

Dawson recognized hard, black, caleareous shales of Triassic age on the
upper part of Pine River South, and McConnell collected fossils from beds cf
this age on Liard river. For a description of the Triassic rocks on Liard river
see pages 80 and 81 of this report.

1Geol, Surv., Can., Sum. Rept., 1917, p. 16 C.