The Carswell showing is located 26 kilometres west of Vernon, north of Bouleau Lake.
In this area, Devonian to Triassic sedimentary and volcanic rocks of the Harper Ranch Group are intruded by Middle Jurassic granitic rocks. Extensive Eocene Penticton Group and Kamloops Group volcanic and sedimentary rocks overlie the older units.
Kamloops Group volcaniclastic sandstone, between andesite flows, hosts agate.