The
Thompson Plateau, also known as the
Okanagan-Thompson Plateau, forms the southern portion of the
Interior Plateau of
British Columbia,
Canada, lying to the west of
Okanagan Lake, south of the
Thompson River and to the east of (although never adjoining it) the
Fraser River. At its most southern point the plateau is squeezed by the mountainous terrain of the
Cascade Range abutting closer to the Okanagan Valley. Its southwestern edge abuts the
Canadian Cascades portion of that extensive range, more or less following the line of the
Similkameen River, its tributary the
Tulameen River, and a series of passes from the area of
Tulameen, British Columbia to the confluence of the
Thompson River with the
Nicoamen River, a few miles east of
Lytton, British Columbia, which is in the Fraser Canyon. Its northeastern edge runs approximately from the city of
Vernon, British Columbia through the valley of Monte Creek to the junction of the same name just east of the city of
Kamloops. Northeast of that line is the
Shuswap Highland.