The area is underlain by Jurassic Bowser Lake Group volcanics comprised of grey to green basaltic to andesitic tuff, breccia and flows. The volcanics are intruded by a Late Cretaceous Bulkley Intrusion comprised of porphyritic granodiorite to quartz diorite.

A silver-lead occurrence is shown on Map 69-1 near the contact between the intrusion and Bowser Lake Group volcanics.