2 
MUSEUM BULLETIN NO. 29. 
Richardson 1 and Isbester. 2 3 These authors, who were the first to write 
on the geology of the region, referred the beds following the Devonian 
limestone at the mouth of Clearwater river to the Marcellus shales, a 
determination based on fossils collected several hundred miles away and 
evidently from a very different horizon. This bituminous formation was 
fully described by McConnell* as the tar sand and referred to the Creta- 
ceous. There appears to be no doubt of its Mesozoic age. The name 
McMurray formation has recently been given to it by McLearn. 4 
STRATIGRAPHIC RELATIONS. 
* \ 
On the northeastern bank of Mackenzie river, opposite Simpson, 
greenish grey clay shale outcrops in horizontal beds exposing a thickness 
of about 140 feet. This shale is without limestone bands and is almost 
or quite free from sandstone bands. It weathers to small flakes of fissile 
shale. Excellent exposures of this shale occur on both sides of the Macken- 
zie about 20 miles above Simpson. Along this part of the river the banks 
expose sections from 50 to 150 feet thick. Fossils are very rare except in 
certain narrow bands of the shale which were located only after consider- 
able searching. Because of the excellent exposures of this shale near 
Simpson, A. E. Cameron has called them the Simpson shales. 5 Neither 
the top nor the bottom of this formation has been observed, but the beds 
which immediately follow are well exposed in the Hay River section on 
the south side of Great Slave lake and carry the Spirifer disjunctus fauna. 
The latest beds preceding it which have been observed ift the Great Slave 
Lake section are those outcropping on the south shore at Sulphur point. 
A small outcrop of the Simpson shale occurs on the west bank below 
the glacial till about 12 miles below Simpson and 2f miles below Martin 
river. 
At station 5720 on the east bank of Mackenzie river, about 5 miles 
above Rabbitskin river, fossils were found in a section exposing about 65 
feet of greenish to bluish grey shales. These include the following species : 
Cyrtina glabra n. sp. 
Buchiola retriostriata 
Paracardium dorisf 
Entomis serratostriata 
Entomis variostriata 
The most northerly locality at which the Portage fauna was found is 
about 150 miles below Simpson on the east bank of Mackenzie river. At 
this locality, station 2729, which is 11 miles below Old Fort Wrigley and 
opposite the lowest of four islands, 40 or 50 feet of dark, lead grey, rather 
soft .shales outcrop which furnished the following species : 
Buchiola retriostriata 
Buchiola dilata n. sp. 
1 Journal of a boat voyage through Ruperts Land, vol. 1, 1851, pp. 122, 177, 
2 Jour. Geol. Soc, Lond., vol. XI, 1855, pp. 509-510. 
3 Geol. Surv., Can., Ann. Rept., vol. V, pt I, 1893, pp. 32D-36D. 
4 Geol. Surv., Can., Sum. Rept., 1916, p. 147. 
6 Geol. Surv., Can., Sum. Rept., 1917, pt. C, p. 26. , 
