64

The dykes range from a few inches to 50 feet or more in width.
Sills of the volcanics are frequently found, but are not nearly so
numerous as the dykes. South of Lake Stanley, near the upper-
most exposed beds of the Skidegate formation, very thick sills
or laccoliths, some up to 200 feet, intrude the sediments. Per-
haps the lessening weight of the superincumbent rocks rendered
it easy for the magma to penetrate between the beds here.

ORIGIN.

The foregoing descriptions of the various formations making
up the Queen Charlotte series show it to be formed of sediments
rapidly accumulated in shallow water. The fossils found through-
out the series are marine, while the coal which is found at a
single horizon in the Haida member, was probably laid down at
a time when shallow estuarine or lagoon conditions prevailed
over considerable portions of the area subject to sedimenta-
tion. The topographic irregularity of the surface on which
the basal sediments of the series were laid down and the varying
character of the lower beds of the Haida formation indicate that
the first accumulations of detrital material took place in more
or less separate basins. These basins were gradually filled, and
deposition, after the period of coal formation, took place in a
single widespread depression.

The large amount of poorly assorted undecomposed felds-
pathic and volcanic rock fragments in the sediments is evidence
of rapid erosion and accumulation of the detrital material.

The locality from which the plutonic rocks found in the
Honna conglomerate were derived is at present unknown, al-
though they may have come from the Queen Charlotte range on
Moresby island. So far as is now known, however, only small
areas of batholithic rocks are exposed in the range, and it may
be that some of the materials of the Honna conglomerate were
accumulated from a more distant source. The well assorted
character of the Honna beds, and the rounded pebbles indicate
transportation from a distance, and the cross-bedded and lentic-
ular nature of the layers is evidence of the deposition of the
Honna conglomerate under the influence of currents.