In the Quesnel region, Tertiary volcanic and sedimentary rocks overlie Paleozoic and Mesozoic rocks of the Cache Creek and Nicola groups. These Tertiary rocks range in age from Paleocene to Pliocene but are dominated by plateau basalts of Miocene age and an underlying sedimentary succession including tuffs, conglomerate, sandstone and shale. Included in this sedimentary assemblage is a horizon of diatomaceous earth from which past production is recorded near Quesnel and Narcosli creeks.
The Diamond showing covers a number of exposures of diatomite but all are badly broken up and contain considerable amounts of clay.