Editing Cascade Range (section)

== Geography ==
[[File:Cascade Range map.png|thumb|Notable volcanoes in the US portion of the Cascades]]
The Cascades extend northward from [[Lassen Peak]] (also known as Mount Lassen) in northern [[California]] to the confluence of the [[Nicola River|Nicola]] and [[Thompson River|Thompson]] rivers in [[British Columbia]]. The [[Fraser River]] separates the Cascades from the [[Coast Mountains]] in Canada,{{sfn|Beckey|2008|pp=191–200}} as does the [[Willamette Valley]] from the upper portion of the [[Oregon Coast Range]]. The highest volcanoes of the Cascades, known as the High Cascades,{{sfn|Martin|2002|p=31}} dominate their surroundings, often standing twice the height of the nearby mountains. They often have a visual height (height above nearby crestlines) of one mile or more. The highest peaks, such as the {{convert|14411|ft|m|adj=on}} Mount Rainier, dominate their surroundings for {{convert|50|to|100|mi|km}}.

The northern part of the range, north of Mount Rainier, is known as the [[North Cascades]] in the United States but is formally named the Cascade Mountains north of the [[Canada–United States border]], reaching to the northern extremity of the Cascades at [[Lytton Mountain]].{{sfn|Duffell|McTaggart|1951|p=8}} Overall, the North Cascades and Canadian Cascades are extremely rugged; even the lesser peaks are steep and glaciated, and valleys are quite low relative to peaks and ridges, so there is great local [[Terrain|relief]].{{sfn|Beckey|2003|pp=9–12}} 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]].{{sfn|Beckey|2008|pp=191–200}}

The range is near the Pacific Ocean and in the region's [[Westerlies|prevailing westerly winds]], so it receives significant rain and snowfall, especially on the western slopes due to [[orographic lift]], with annual snow accumulations of up to {{convert|1000|in|cm}} (= {{convert|83|ft|m}}) in some areas. [[Mount Baker]] in Washington recorded a national record single-season snowfall in the winter of 1998–99 with {{convert|1140|in|cm}} (= {{convert|95|ft|m}}).<ref>{{Cite web |url=http://www.ncdc.noaa.gov/extremes/ncec/ |title=National Climate Extremes |publisher=National Oceanic and Atmospheric Administration  |archive-url=https://web.archive.org/web/20120606081856/https://www.ncdc.noaa.gov/extremes/ncec/ |archive-date=June 6, 2012}}</ref> 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 {{convert|500|in|cm}} of annual snow accumulation, such as at [[Lake Helen (Lassen Peak)|Lake Helen]], near Lassen Peak.<ref>{{Cite news |last=McLaughlin |first=Mark |url=http://www.tahoedailytribune.com/article/20101014/COMMUNITY/101019946 |title=Weather Window: The snowiest spot in California is Lake Helen near Lassen Volcanic National Park |date=October 14, 2010 |work=Sierra Sun |access-date=November 9, 2013 |location=Truckee, California}}</ref> 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''),{{sfn|Beckey|2008|p=16}} 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.{{sfn|Mueller|Mueller|2002|p=99}} Annual rainfall is as low as {{convert|9|in|mm}} on the eastern [[foothill]]s due to a [[rain shadow]] effect.{{sfn|Ernst|2000|p=479}}

[[File:Columbia River Gorge (3).jpg|thumb|The [[Columbia Gorge]] marks where the [[Columbia River]] splits the Cascade Range between the states of Washington and Oregon.]]

Beyond the eastern foothills is an [[arid]] plateau that was largely formed 17 to 14&nbsp;million years ago by the many flows of the [[Columbia River Basalt Group]]. Together, these sequences of fluid [[volcanic rock]] form the {{convert|200000|sqmi|km2|adj=on}} [[Columbia Plateau]] in eastern Washington, Oregon, and parts of western Idaho.<ref>{{Cite web |url=http://geology.isu.edu/Digital_Geology_Idaho/Module10/mod10.htm |title=Columbia River Basalt Province |last1=Straub, Kristen |last2=Link, Paul |website=Digital Geology of Idaho |publisher=Idaho State University |access-date=November 3, 2013 |archive-date=October 23, 2013 |archive-url=https://web.archive.org/web/20131023061110/http://geology.isu.edu/Digital_Geology_Idaho/Module10/mod10.htm |url-status=dead }}</ref>

The [[Columbia River Gorge]] is the only major break of the range in the United States. When the Cascades began to rise 7&nbsp;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, carving out the gorge and major pass seen today. The gorge also exposes uplifted and warped layers of basalt from the plateau.<ref name="nwcouncil">{{Cite web |url=http://www.nwcouncil.org/history/ColumbiaRiverGorge |title=Columbia River Gorge |last=Harrison |first=John |date=October 31, 2008 |website=Columbia River History |publisher=Northwest Power and Conservation Council |access-date=November 9, 2013}}</ref><ref name="burke">{{Cite web |url=http://www.burkemuseum.org/static/geo_history_wa/Cascade%20Episode.htm |title=The Cascade Episode: Evolution of the Modern Pacific Northwest |publisher=Burke Museum of Natural History and Culture, University of Washington |access-date=November 9, 2013}}</ref>