PRE-CAMBRIAN LITERATURE OF NORTH AMERICA 185 
The pre-Beltian area forms a core surrounded by Beltian and 
other younger rocks. It is roughly lenticular in outline, its longest 
direction extending from northwest to southeast. It is about 
400 miles in length and 100 miles in width. The quartzites in this 
series represent true sandstones, probably derived from a granitic 
area. Daly believes that the intrusions in the pre-Beltian are of a 
type characteristic only of the early pre-Cambrian and resemble the 
Laurentian granites of the Canadian Shield. Sills and lt par lit 
injections are characteristic. The metamorphism of the pre- 
Beltian, he believes, is due almost entirely to the weight of over- 
lying beds and to temperature. The facts on which this conclusion 
is based are the parallelism of the fissility and the bedding, the 
almost complete absence of ordinary folds, the low dip of the beds, 
and the parallel fissility of the dykes with that of the adjacent beds. 
Metamorphism of this type, Daly believes, is typical of the pre- 
Cambrian only. He ascribes it to a steep temperature gradient of 
the earth’s crust and to the abundance of mineralizers in the 
granitic intrusions of that time. The pre-Beltian of this area, he 
believes, is probably correlated with the Priest River terrane to 
the south, the only difference between the two being that as 
yet no granites have been found in the latter. Equivalent rocks 
also probably occur on the west shore of Coeur d’Alene Lake. 
The Beltian system of the area is classified as follows: 
COLUMNAR SECTION OF THE BELTIAN SYSTEM IN 
THE SELKIRK Mporoainate 
- Thickness in Feet 
Top, erosion surface 
(Ross, quartzite (in part) . . . 2,500 
Glacier Division Nakimu limestone . . : 350 
(‘Selkirk series’’ of Dawson) | Cougar formation (quariaire with 
metangillitieibeds)) 54 ane £O;S00 
Laurie formation (metargillite, often cal- 
careous; with subordinate interbeds of 
eee limestone and quartzite; basal bed, lime- 
Albert Canyon Division a : ; 
Bh core?’ ‘! stone 50 feet thick) eh MONO e BETS OOO 
lilecillewach quartzite, 9 sae I,500 
Saison Moosesmetarcillite;s) 2 =) ae oe 2,150 
| Limestone (naarble) mee ah i ees 170 
Bersall’ GmantAve Ma hag MGR tg a fa 280 
Base, unconformity with Shuswap terrane 
