43

Liard River Valley

At the type locality, on an island and on the south bank of Liard River
near Hades (Hell) Gate (See Figure 4 and Plate IV B), Kindle (1946)
measured a section of the upper part of the Liard formation:

Thickness
(A Feet
roximate
Overlying dark shales of Garbutt formation *
Sandstone, calcareous; and limestone...............+..+- Walefeed w200
Sandstone, hard, calcareous; and limestone; with Nathorstites
AS Rect oreee dria deste Cam A onion cris aie CRT een 50

The contact with the overlying, Lower Cretaceous, possibly partly Jurassic,
Garbutt shales is structurally conformable.

A better section is exposed in the belt of Triassic strata that crosses
Liard River east of Hades (Hell) Gate, between Brimstone and Crusty
Creeks (See Figure 4). Here, Kindle (1946) measured more than 600 feet
of mostly massive, thick-bedded, occasionally thinly laminated, calcareous
sandstone, grey limestone, arenaceous limestone, and some shale. Near
the top of this section is a bed with numerous shells of the brachiopod
‘Coenothyris’. In a flat-lying vein near river level at this locality, crystals
of quartz about 4 inches long have been collected. The contact with the
underlying Toad formation is concealed.

Farther east, at the mouth of Toad River, the Liard formation is
missing in the section, and the shales of the Garbutt formation rest directly
on the Toad formation (Kindle, 1946).

The Liard formation is exposed upstream for many miles above Hades
(Hell) Gate, for McConnell (1891) collected species of the Nathorstites
fauna at the lower end of the canyon west of Hades (Hell) Gate and at the
Rapids of the Drowned.

Tetsa River Valley

The Liard formation is recognized in Tetsa Valley, along the Alaska
Highway, and, as on Liard River, is thick in the west and thins rapidly to
the east (McLearn, 1947A).

On the east slope of Cameron Hill and on Smith and Shaw Hills,
between miles 378 and 375 on the Alaska Highway (See Figure 7), a thin
section only of massive, fine sandstone and limestone, overlying beds typical
of the Toad, can be referred to the Liard formation. On the axis and on
the west limb of the Williams Valley anticline near and west of mile 378,
the Liard thickens rapidly and is exposed on a high and abandoned Highway
location north of the present roadway. ‘There it consists of massive, thick
beds of fine sandstone and grey limestone, fossiliferous in places and con-
taining specimens of the brachiopod genus ‘Coenothyris’ and of the pelecypod
genera Pecten, Ostrea, and Pinna. Although no ammonoids have been
found, the brachiopods and pelecypods are of the Nathorstites fauna, which
is represented in the Liard formation on Liard River. These beds on the
north side of the Alaska Highway extend nearly 2 miles to the west on a
long ridge where they conceal the underlying beds of the Toad formation.

The Liard formation is also represented in the second and broad belt
of Triassic that crosses the Highway approximately between miles 382-5