Regionally the area is predominantly underlain by basaltic volcanic rocks of the Upper Triassic Karmutsen Formation (Vancouver Group). The basalts range from feldspar porphyritic to augite porphyritic with amygdaloidal and aphanitic varieties also present. Pillow basalt flows are common. Limestone occurs locally as narrow lenses with limited lateral extent.

The Long B occurrence is underlain by a composite granodiorite to quartz diorite stock in contact with altered Karmutsen Formation basalt, porphyritic basalt and basalt breccia. Chlorite and epidote alteration is common near intrusive contacts. Local areas of intense chlorite, kaolin and potassic alteration are common within the intrusion. Silicification is accompanied by abundant pyrite in lenses and heavy disseminations.

The volcanic/intrusive contact is well exposed at the Upper Creek showing where it strikes 343 degrees with steep west dips. A large quartz vein occurs adjacent to the contact and is hosted in diorite. It strikes 022 degrees and dips 66 degrees northwest. The vein structure passes westward into volcanic rocks and becomes progressively less well-defined. The vein is mineralized with massive chalcopyrite, pyrite and bornite and is exposed intermittently over a strike length of 75 metres. Rock samples from the vein assayed up to 8.19 grams per tonne over 0.3 metres (Assessment Report 18671). A related quartz vein referred to as the Southeast vein is 450 metres further downslope and on strike with the Upper Creek showing. A rock sample in 1950 assayed 13.36 grams per tonne gold over a 20 centimetre width (Minister of Mines Annual Report 1950).