During dry periods, the mudflats of one plain are dominated by mineral salts, these salt plains being unique in Canada. Buffalo-Lake Robertson Plain is underlain by impervious shale and discontinuous permafrost, resulting in vast areas of muskeg with shallow lakes and meandering creeks. The uplands of Birch and Caribou plateau have been eroded by rivers to form long, incised gorges with long stratigraphic cross-sections of bedrock and large alluvial fans. The plateau is of Lower and Upper Cretaceous age. Gypsum and anhydrite are abundant and minor amounts of salt, potash and limestone occur.
Glacial deposits cover much of the area.
The climate is boreal continental with long cold winters and short warm summers. Annual precipitation is about 310mm, but annual evaporation is 410mm. This moisture deficit, coupled with an average 40 thunderstorms per season, puts the park in an extreme forest-fire weather zone. The brief frost-free period extends from early June to early September but much of the park is permanently underlain by discontinuous permafrost. Winter daylight period is short, while midsummer daylight period is over 20 hours.