is

Table of Formations.

Superficial deposits Pleistocene and Recent.

Tertiary sediments Upper Miocene or Pliocene.

Tertiary volcanics and intrusives. Upper Miocene or Pliocene and
Dacites, andesites, and basalts probably Eocene.

Queen Charlotte series Middle or upper Jurassic or
Skidegate sandstones. Lower Cretaceous, and prob-
Honna conglomerate. able Middle and Upper Cre-
Haida sandstones and shales. taceous.

Image (basal) conglomerates.
(May include contemporaneous volcanics).

Batholithic intrusives Upper Jurassic.
Granodiorite, diorite, etc.

Vancouver group Triassic and Jurassic.
Argillites, slaty shales.

Metamorphic volcanics, andesites, and basalts.

He also clearly recognized the important unconformity at
the base of the Queen Charlotte series, although he includes in
the latter some volcanic conglomerates which more detailed
work has shown to be pre-Cretaceous.

As Clapp’s descriptions vary only in detail from those in
the present report, they are not summarized here.

SUMMARY OF PRESENT REPORT.

For those who are mainly interested in the economic geology
of the area, this summary will serve as a sufficiently full des-
cription of the general geology. Of necessity, proofs of the
conclusions arrived at cannot be given in this summary; for the
proofs, and for further details of the geology of the island, the
reader is referred to the main part of the report.

GENERAL GEOLOGY.

The oldest formations exposed on Graham island comprise
metamorphic sediments and volcanic rocks, of lower Jurassic
and perhaps Triassic age, which are correlated in general with the
Vancouver group. These basal rocks are divided into two for-
mations, the Maude formation, lower Jurassic and perhaps
Triassic in age, and the Yakoun formation, of middle Jurassic
age, which conformably overlies it.