local relief. The southern part of the Canadian Cascades, particularly the Skagit Range, is geologically and topographically similar to the North Cascades, while the northern and northeastern parts are less glaciated and more plateau-like, resembling nearby areas of the Thompson Plateau. Because the range is near the Pacific Ocean and in the region's prevailing westerly winds, there is much rain and snow there, especially on the western slopes due to orographic lift, with annual snow accumulations of up to (= ) in some areas. Mount Baker in Washington recorded a national record single-season snowfall in the winter of 1998–99 with (= ). Before that year, Mount Rainier held the American record for snow accumulation at Paradise in 1978. It is not uncommon for some places in the Cascades to have over of annual snow accumulation, such as at Lake Helen, near Lassen Peak. Most of the High Cascades are therefore white with snow and ice year-round. The western slopes are densely covered with Douglas-fir (Pseudotsuga menziesii), western hemlock (Tsuga heterophylla) and red alder (Alnus rubra), while the drier eastern slopes feature mostly ponderosa pine (Pinus ponderosa), with some western larch (Larix occidentalis), mountain hemlock (Tsuga mertensiana) and subalpine fir (Abies lasiocarpa) and subalpine larch (Larix lyallii) at higher elevations. Annual rainfall is as low as on the eastern foothills due to a rain shadow effect. Beyond the eastern foothills is an arid plateau that was largely created 17 to 14 million years ago by the many flows of the Columbia River Basalt Group. Together, these sequences of fluid volcanic rock form the Columbia Plateau in eastern Washington, Oregon, and parts of western Idaho. The Columbia River Gorge is the only major break of the range in the United States. When the Cascades began to rise 7 million years ago in the late Miocene, the Columbia River drained the relatively low Columbia Plateau. As the range grew, erosion from the Columbia River was able to keep pace, creating the gorge and major pass seen today. The gorge also exposes uplifted and warped layers of basalt from the plateau. History Indigenous peoples have inhabited the area for thousands of years and developed their own myths and legends about the Cascades. In these legends, St. Helens with its graceful, pre-1980 appearance was regarded as a beautiful maiden for whom Hood and Adams feuded. Native tribes also developed their own names for the High