74

the sandstones are frequently cross-bedded. At Skonun point
the beds are disposed in an east-west anticline, apparently
faulted on the crest, and with dips up to 60 degrees. Most of the
exposures seen were flat lying, or nearly so. The formation as a
whole appears to have a gentle northeast dip, and is uncon-
formable on the rocks of the Vancouver group in township 7.

The total thickness of the Skonun formation is unknown.
A bore-hole put down at Skonun point for the American-Canadian
Coal Company is reported to have penetrated to a depth of
1,003 feet, at an angle of 45 degrees. Owing to the dip of the
measures, this nearly represents the true stratigraphic thickness
passed through, so the formation may be considered to be over
1,000 feet thick.

The writer has not seen the contact between the overlying
Masset and the Skonun formations, but from the general areal
distribution of the Tertiary rocks, it is thought that the Masset
formation overlies the Skonun with overlap or unconformable
relations. The alternating sediments and basalt flows on the
Mamin river may indicate that the upper part of the Skonun
formation contains intercalated basalt, but the relations are not
clear.

Origin. The variable character of the sediments and their
cross-bedded structure points to a shallow water place of origin.
The fossil leaves indicate a location near shore, while the marine
fossils show that the water was at least brackish. The beds of
lignite, though derived in part probably from transported
material, hints at a freshwater origin for part of the formation
at least. On the whole, it seems best to consider the Skonun
sediments as beds formed in shallow estuarine basins, parts of
which were at times cut off from the sea and converted into
freshwater lakes or swamps, and at times reverted to estuarine
or marine conditions.

Age. The fossils collected from Skonun point by Dawson
were examined by Whiteaves, and his determinations and re-
marks are given here in full.?

1 Geol. Surv., Can., Rept. of Prog. 1878-79, p. 87B.

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