The Westwold Clay deposit is located 16 kilometres west of Falk- land, in the Salmon River Valley.

In this area, sedimentary rocks of the Devonian to Triassic Harper Ranch Group are in probable unconformable contact with Upper Triassic to Lower Jurassic Nicola Group sedimentary and volcanic rocks. Middle Jurassic granitic rocks of the informally named Terrace Creek batholith intrude these rocks. Extensive Eocene Kamloops Group volcanic rocks cap the older rocks.

Quaternary glaciolacustrine beds host a clay deposit quarried for industrial use. A grey, calcareous clay suitable for good quality brick and tile was mined by the Falkland Brick, Tile and Pottery Ltd. in the late 1940s.