60

that the rocks regain their north-south strike with an easterly
dip, forming the western limb of a syncline, and that they ex-
tend southward under the Tertiary volcanic veneer to Skide-
gate inlet, west of the mouth of Slatechuck creek. The Honna
formation thus forms a horseshoe-shaped outcrop on Graham
island.

Lithology.

The Honna formation is mostly composed of conglomerate
with some sandstones and sandy shales. Some of the conglo-
merates at the base are coarse, with pebbles up to 3 feet in dia-
meter but averaging much less. The most common conglo-
merate is composed of about 60 per cent of well rounded pebbles,
from ~ inch to 6 inches in diameter but averaging about 14
inches, in a coarse sandy matrix. Most of the pebbles are plu-
tonic rocks—light grey diorite, dark grey diorite or gabbro,
fine black diorite, granodiorite both even granular and gneissic,
fine porphyritic diorite, etc. Coarse quartzites, fragments of
argillites of the Maude formation, chert, and quartz also are
found, but recognizable fragments of the Yakoun volcanics
are rare or absent.

The sandstone interbeds in the conglomerate are generally
pinkish, medium-quartzose varieties, and the shaly beds are
black, fine-grained, hard slaty rocks.

Stratigraphy and Structure.

The lowermost beds of the formation exposed at Lina
Narrows are coarse sandstones, transitional from the upper
Haida; then come 6 feet of very coarse conglomerate, with well
rounded pebbles averaging over 6 inches. Above this are bands
of medium conglomerate with thin, cross-bedded and lenticular
intercalations of sandstones. These conglomerate beds form
the lower few hundred feet of the formation and above them are
softer shales and crossbedded sandstones, forming the middle
half, while conglomerates make up the upper 500 feet or
so of the formation.

On the south side of Nose point, dark grey, slaty shales of
the Honna formation are cut by a S-inch, medium-grained,