“Ge
Carboniferous

At least one-quarter of the map-arcea is underlain by
rocks mapped as Carboniferous. Sedimentary, extrusive, and
metamorphic types are all woll represented. The close folding and
extensive faulting of these rocks makes it impossible to determine
their exact stratigraphic sequence, and, therefore, the summarizod
section below is merely an attempt to indicate the gencral order
of succession, It is also impossible to make more than a rough
approximation of their total thickness or of that of the various
groups, but the estimates given below indicate the relative amount
of cach group. The order is descending, group 1 being the oldest.

| Maximum | Arcal

| Thickness Extont
Se ee ee ee ee aa Se eee
Group 5 Massive limestono, and HeOe
some intercalations of 4,000 + ; 90 square miles

argillite, chert, and

(90 per cent limestone)
andesite greenstone

|
Group 2 Andesite greenstone |
with minor amounts 10,000 oh | 150 square miles
of argillite, chert, | (90 per cont greenstone )
|
|
| \

and limestone

Group 1 Chert, argillite, and

slato with some ande- 10,000 + 150 square miles
site greenstone, and 40 per cent chert
minor amounts of lime- HO) oneal WSS
stone and slate
15 por cent greenstone
Oh Ua limestone

Rane en ee

Total thickness 24,000 +

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8S BE IS iat er ee a