The area is underlain predominately by andesitic agglomerates and tuffs of the Middle Jurassic Yakoun Group with lesser Upper Cretaceous Honna Formation conglomerates. The rocks are cut by rhyolite dikes and diorite intrusives and are bounded to the east by the northwest trending Sandspit fault.
A barite vein with associated galena and sphalerite occurs in Yakoun volcanics.