The Tsowwin River flows southwest into Tahsis Inlet, approximately 15.5 kilometres south-southeast of the community of Tahsis.

The area is underlain by Upper Triassic Vancouver Group volcanics and sediments comprised of Karmutsen Formation basalts and carbonates and clastics of the Quatsino and Parson Bay formations. Granodiorite of the Early to Middle Jurassic Island Plutonic Suite and Eocene Catface or Mount Washington Intrusions has intruded the Vancouver Group rocks.

It appears that most of the gold was derived from bars or in crevices in the bedrock of the river bed, or from benches along the side of the creek.

Placer gold in reported in the Tsowwin River drainage and is likely related to gold- bearing quartz-calcite veins such as those located on the Vivian (MINFILE 092E 006) and Mohawk (MINFILE 092E 005) occurrences. These were discovered in the 1930’s after the discovery of lode gold deposits in the Zeballos River area to the northwest.