Evaporite deposits forming in playas are common on the Chilcotin Plateau owing to the semi-arid climate of much of the region. Most of the annual precipitation is in the form of snow, the summer months being relatively rain free.

The Nemaia Valley contains several small ephemeral lakes which occupy depressions with largely internal drainage. Several of these lakes, such as Towydkin, Tsun and Kliyul, contain evaporitic salt deposits composed mainly of sodium carbonate. The sodium carbonate occurs as relatively pure deposits within the central part of these depressions after water evaporation during summer months, surrounded by greyish carbonate-rich muds developed around the edges of the depressions.