It originates at the outlet of Little Shuswap Lake at the town of Chase and flows approximately 58 kilometres (36 mi) southwest and west through a wide valley to Kamloops where it joins the North Thompson River to form the main stem Thompson River.

[4] During the Late Pleistocene, the drainage of the glacial lakes formed the floodplain flanked by deeply carved terraces along both sides of the valley.

During the Holocene Climate Optimum (HCO), the postglacial vegetation changed markedly as warmer and dryer conditions replaced cool and moist ones.

Douglas fir, grasses and sagebrush increased, while pine declined.

Then, a period of cooler and wetter conditions gave way to the modern climate about 4,500 years ago.