The Pacific Northwest is a diverse geographic region, dominated by several mountain ranges, including the Coast Mountains, the Cascade Range, the Olympic Mountains, the Columbia Mountains, and the Rocky Mountains. The highest peak in the Pacific Northwest is Mount Rainier, in the Washington Cascades, at . Immediately inland from the Cascade Range are broad, generally dry plateaus. In the US, this region is known as the Columbia Plateau, while in British Columbia, it is the Interior Plateau, also called the Fraser Plateau. The Columbia Plateau was the scene of massive ice-age floods, and as a consequence, there are many coulees, canyons, and the Channeled Scablands. Much of the plateau, especially in eastern Washington, is irrigated farmland. The Columbia River cuts a deep and wide gorge around the rim of the Columbia Plateau and through the Cascade Range on its way to the Pacific Ocean.