The Thunder-Massive Sulphide zone is located on the south side of Ursus Creek, approximately 5 kilometres upstream from the confluence with Bedwell River, and 30 kilometres northeast of Tofino, B.C.

The area is underlain by middle to late Triassic Karmutsen basalt. These basalts are overlain by massive to thickly bedded calcareous mudstones of the Quatsino Formation. These volcanic and stratified rocks have been invaded by the middle to late Jurassic biotite-hornblende granodiorite and quartz diorite. The area has been subjected to major faulting with a dominant northwest-southeast trend.

Locally, massive sulphide mineralization, primarily magnetite with traces of pyrite and chalcopyrite, occurs in pods 1.0 by 1.5 metres in size hosted in Karmutsen volcanics cut by dikes.

It is likely that the THUNDERBIRD-MASSIVE SULPHIDE occurrence is the western extent of the Ursus Creek cataclasis zone is interpreted as gold-bearing quartz-carbonate-minor pyrite vein-stockwork related to narrower, but laterally extensive cataclastic deformation zones. Chlorite zones are developed in Triassic Karmutsen andesite-basalt that is characterized by finely disseminated pyrite and carbonate blebs, streaks and late-stage fracture fillings. Gold values are related to late-phase albite enriched end phases of mid-Jurassic intrusive activity, and mineralization is considered to be of intrusion-related vein-stockwork-breccia type.

Two grab samples returned 340 and 210 parts per billion gold (Assessment Report 20474).

The area was originally explored in 1939 with the discovery of float containing coarse gold near the junction of Ursus and Thunderbird creeks. In 1979, the property was acquired by S. Craig and later optioned to Eldorado Minerals and Petroleum as the Ureka and Opus claims. In 1984, Eldorado completed a program of trenching and geochemical sampling that identified the Thunderbird (Camp) Zone (MINFILE 092F 067). From 1986 to 1987, Pacific Sentinel Gold completed programs of geochemical surveying, geological mapping and magnetometer and VLF surveys. This work identified three new zones, including the Junction (MINFILE 092F 450), and Mid-Pad (MINFILE 092F 449) occurrences. From 1988 to 1989, Pezgold Resource optioned the property and completed a program of diamond drilling on the Junction zone, and prospecting which led to the discovery of the Elmer zone to the east. In 1990, Pacific Sentinel Gold completed a program of geological mapping, rock sampling and trenching. In 1995, the area was prospected as the Thunderbird claims by S. Salmon. In 1999, the area was claimed as a part of the Thunder claims and a program of geological mapping, geochemical sampling and geophysical surveys were completed on the Elmer zone.