North Cascades

The North Cascades are a section of the Cascade Range of western North America. They span the border between the Canadian province of British Columbia and the U.S. state of Washington and are officially named in the U.S. and Canada as the Cascade Mountains. The portion in Canada is known to Americans as the Canadian Cascades, a designation that also includes the mountains above the east bank of the Fraser Canyon as far north as the town of Lytton, at the confluence of the Thompson and Fraser Rivers.

They are predominantly non-volcanic, but include the stratovolcanoes Mount Baker, Glacier Peak and Coquihalla Mountain, which are part of the Cascade Volcanic Arc.

The U.S. section of the North Cascades and the adjoining Skagit Range in British Columbia are most notable for their dramatic scenery and challenging mountaineering, both resulting from their steep, rugged topography. While most of the peaks are under 10,000 feet (3,000 m) in elevation, the low valleys provide great local relief, often over 6,000 feet (1,800 m). The summits of the rest of the Canadian Cascades are not glaciated in the same way and feature rock "horns" rising from plateau-like uplands, with the Manning Park and Cathedral Park areas known for their extensive alpine meadows, as is also the case with the eastern flank of the US portion of the range. Portions of the US side of the range are protected as part of North Cascades National Park.

The large amount of precipitation, much of it in the form of snow, and the resulting glaciation, combine with the regional uplift to create a dramatic landscape in the western part of the range. Deep, U-shaped valleys carved by glaciers in Pleistocene time separate sharp ridges and peaks carved into steep shapes by more recent snow and ice.

The eastern and northernmost parts of the range are much more plateau-like in character, though in the case of the northernmost areas graven by deep valleys along the flank of the Fraser Canyon, notably that of the Anderson River.

The Fraser River and the adjoining lowland on its south bank form the northern and northwestern boundary of the range. On the east, the Okanogan River and the Columbia River bound the range in the United States, while the northeastern boundary of the range departs the Thompson via the Nicoamen River and runs via Lawless Creek, the Tulameen River and Copper Creek to the Similkameen River. On the west, the foothills of the range are separated by a narrow coastal plain from Puget Sound except along Chuckanut Drive between Bellingham and Mount Vernon, where they abut the Sound directly.

The southern boundary of the North Cascades is less definite. For the purposes of this article, it will be taken as U.S. Highway 2, running over Stevens Pass, or equivalently, the Skykomish River, Nason Creek, and the lower Wenatchee River. This roughly follows Beckey's geologic division in Cascade Alpine Guide and the definition used by Peakbagger.com. Sometimes the southern boundary is defined by Snoqualmie Pass and the approximate route of Interstate 90. Sometimes the term "North Cascades" or "northern Cascades" is used for the entire range north of the Columbia River.

Geologically, the rocks of the North Cascades extend south beyond Stevens Pass and west into the San Juan Islands. The significance of the geologic transitions to the Okanagan Highland to the east and the Interior Plateau and Coast Mountains to the north are less agreed upon.