What is the British Columbia Interior Plateau?

The British Columbia Interior Plateau is the largely flat to gently rolling interior region of central British Columbia, lying between the Coast Mountains in the west and the Columbia and Rocky Mountains in the east. The Plateau covers about 180,000 square kilometres at elevations of 600 to 1,500 metres and includes several distinct sub-regions: the Cariboo Plateau in the north, the Chilcotin Plateau west of the Fraser River, the Thompson Plateau between the Fraser Canyon and the Okanagan Valley, the Okanagan Plateau in the south, the Nicola Plateau, and the Fraser Plateau.

The Interior Plateau is the geological remnant of an ancient volcanic plateau that was uplifted during the formation of the Cordillera and then dissected by river erosion. Lava flows of the Chilcotin Group basalts (about 25 to 5 million years old) underlie much of the Cariboo and Chilcotin sub-regions. The Pleistocene ice sheets covered the entire plateau and left characteristic glacial landforms including drumlins, eskers, kames, and outwash plains. The plateau is drained by the upper Fraser, Thompson, Nechako, Chilcotin, and Okanagan Rivers.

The Interior Plateau has a continental climate with cold dry winters and warm dry summers (semi-arid in the southern Okanagan, where annual precipitation is below 300 millimetres). The Okanagan Valley is the only desert region in Canada, with the Pocket Desert at Osoyoos (the country's hottest summer temperatures, frequently above 35 degrees Celsius) supporting rattlesnakes, scorpions, antelope brush, and prickly pear cactus. The Okanagan is also Canada's most important wine region after the Niagara Peninsula. The Cariboo and Chilcotin regions are famous for cattle ranching and have been the heart of British Columbia's ranching industry since the 1860s Cariboo Gold Rush.

The Interior Plateau is the homeland of the Secwepemc, Tsilhqot'in, Nlaka'pamux, Stl'atl'imx (Lillooet), Syilx (Okanagan), Sekani, Wet'suwet'en, and Carrier (Dakelh) First Nations. None of these nations signed historic numbered treaties (the numbered-treaty process did not extend to British Columbia except in the northeast, where Treaty 8 was signed in 1899). The 2014 Tsilhqot'in Nation v. British Columbia decision of the Supreme Court of Canada issued the first-ever declaration of Aboriginal title in Canada, covering about 1,750 square kilometres of the Tsilhqot'in Plateau in the Interior Plateau. The 2020 Memorandum of Understanding between the Wet'suwet'en Hereditary Chiefs and the federal and BC governments addresses Wet'suwet'en title rights in the northern Interior Plateau.