The Gagen Creek deposit consists of well-worn and fairly coarse placer gold in bench-type deposits. Bedrock in the area is primarily basalt.

"Data from the Cariboo mining district indicate that supergene leaching of gold dispersed within massive sulphides by Tertiary deep weathering followed by Cenozoic erosion is the most likely explanation for the occurrence of coarse gold nuggets in Quaternary sediments" (Exploration in British Columbia 1989, page 147).