The Main Valley zone is located on the north western shore of the East Sooke Peninsula, approximately 1.5 kilometres south of Sooke.

The area is underlain by the Eocene Sooke Gabbro, which forms the basement of the Metchosin Volcanics and is composed of coarse-grained gabbro with about equal parts of bytownite and diopside and about 5 per cent olivine. Local agmatization, amphibolitization and mineralization of the gabbro occurred later along shear zones.

Locally, the north trending "Sooke River Break" (fault) is exposed. The visible portion of the fault consists of sheared and brecciated gabbro and hornblendite with numerous calcite stringers and gougy chloritic slips. Native copper occurs in flakes and thin coatings along small fracture planes in the sheeted wallrock of the shear. A few grains of chalcopyrite and pyrrhotite have been noted along the wallrock of the "main valley" (Assessment Report 61).

In 1951, programs of geological mapping and ground geophysical surveys were completed on the area as the June, Lorna, Moffat and Pac claims.