The Cascade Range extends from southern British Columbia to northern California, through the states of Washington and Oregon, for a total length of approximately 1,100 kilometres. It incorporates part of the Cascade volcanic arc, including Mount Rainier (4392 meters high) and Mount Saint Helens (2549 m).
The Cascade Range glacial system is the largest in the United States except Alaska, and is particularly complex in the North Cascades.
In order to protect this biological diversity and natural resources, the bulk of the range is protected, with four national parks having been established in situ.
To date, the uncontaminated and overall well-preserved nature of the Cascade chain allows it to be listed among the tourist attractions of the West Coast.
The climatic characteristics of the area mean that the western slopes are densely wooded and composed of Oregon pines, western hemlocks and red alders, while the drier eastern slopes are mainly composed of yellow pines and, at higher altitudes, western larches.
The first geological activities relating to the formation of the volcanic arc, still active today, began 36 million years ago, following the subduction of the Juan de Fuca plate under the North American one. The risks associated with volcanism are estimated to be significant, but the monitoring activity of geologists in the area remains intense.
The Columbia River constitutes the main topographic discontinuity of the chain, crossing it from east to west, with its basin covering much of its slopes. The relief oriented from north to south is an obstacle to the mild and humid ocean currents coming from the Pacific Ocean. Due to the altitude, heavy precipitation results in considerable amounts of snow, as is the case on Mount Baker.
On the eastern side of the range, rainfall is much lower and the climate is continental, with greater variations in daily and seasonal temperatures. This difference makes its impact felt on the vegetation, which is mainly composed of conifers: if to the west of the ridges Oregon pine and western hemlock dominate, yellow pine, twisted pine and western larch adapt better to the arid lands of the east.
The northern part of the chain, known as the North Cascades, cooler and with various reliefs of a certain elevation which are presented with numerous glaciers, is home to the hemlock mertensiana, the silver fir and the rock fir. The fauna is very varied, but some species appear threatened by human impact.
Only three rivers cross the Cascade Range, from east to west: from north to south, the Columbia and the Klamath deserve mentioning first and foremost, as well as the Pit which is a tributary on the left bank of the Sacramento River.