Lake Allison
{{Infobox body of water
|name = Lake Allison
|inflow = Glacial Lake Missoula
|outflow =
|basin_countries = United States
|type = Temporary lake (formed periodically from 12,000 to 15,000 years BP)
|location = Willamette Valley, Oregon
|coordinates = {{coord | 45 | -123 | type:event_region:US-OR | display=inline,title}}
|length = {{convert|111|mi|km|abbr=on}}
|width = {{convert|31|mi|km|abbr=on}}
|area = {{convert|3000|sqmi|km2|abbr=on}}
|depth = {{convert|200|ft|m|abbr=on}}
|max-depth = {{convert|400|ft|m|abbr=on}}
| pushpin_map = Oregon#USA
| pushpin_label_position =
| pushpin_map_alt = Location of Lake Allison in Oregon, USA.
| pushpin_map_caption =
| website =
| reference =
}}
Lake Allison was a temporary lake in the Willamette Valley of Oregon, formed periodically by the Missoula Floods from 15,000 to 13,000 BC. The lake is the main cause of the rich and fertile soil that now characterizes the Willamette Valley.
History
File:Lakes-Washington-Oregon-9.GIF
Willamette Valley fertility, like the Palouse silt,{{cite web|url=http://www.columbiariverimages.com/Regions/Places/missoula_floods.html|archive-url=https://web.archive.org/web/20080929062024/http://columbiariverimages.com/Regions/Places/missoula_floods.html|url-status=usurped|archive-date=September 29, 2008|title = The Columbia River - Missoula Floods}} is in large part due to the largest freshwater flood scientifically documented{{cite web|url=http://www.waymarking.com/waymarks/WM19FR |title=Willamette Falls & Missoula Flood, Oregon - Glacial Lake Missoula Flood Features on |publisher=Waymarking.com |date= |accessdate=2022-05-03}} in history. The ice floods started in Lake Missoula in Montana 12,000 to 15,000 years ago during the Pleistocene{{cite web |url=http://depts.clackamas.cc.or.us/science/physci/geology/G145/lectures/wil%20valley.htm |title=Geology of the Willamette Valley |url-status=dead|archive-url=https://web.archive.org/web/20090525234411/http://depts.clackamas.cc.or.us/science/physci/geology/G145/lectures/wil%20valley.htm |archive-date=25 May 2009 }} and flowed down through eastern Washington, bringing fertile soil to the valley as it flowed out the Columbia River Gorge. The narrows at Kalama, Washington, restricted the flow of water, causing it to back up and flood the Willamette Valley to a depth of {{convert|300|to|400|ft|m}} above sea level as far south as Eugene.{{cite web |url= http://vulcan.wr.usgs.gov/Glossary/Glaciers/IceSheets/description_lake_missoula.html |title= Glacial Lake Missoula and the Missoula Floods |publisher= United States Geological Survey |access-date= 6 July 2012}}{{cite book |author1=John Eliot Allen |author2=Marjorie Burns |author2-link=Marjorie Burns |author3=Scott Burns |title=Cataclysms on the Columbia: The Great Missoula Floods|url=https://books.google.com/books?id=jeTESR-vvJ4C&pg=PA181|access-date=6 July 2012|year=2009|publisher=Ooligan Press|isbn=978-1-932010-31-2|pages=181–182}}Cataclysms on the Columbia, by John Elliott Allen and Marjorie Burns with Sam C. Sargent, 1986. Pages 175–189. The Willamette Valley had multiple floods during the last ice age, possibly reaching 100 floods separated by centuries, to depths of 300–400 feet.Geology of Oregon, by Elizabeth L. Orr, William N. Orr and Ewart M. Baldwin, 1964. Pages 211–214. If {{convert|300|to|400|ft|m|adj=mid|-deep}} floodwaters descended on the valley today, in Portland (elevation {{convert|20|ft}}, only the tops of the West Hills, Mount Tabor, Rocky Butte, Kelly Butte and Mount Scott would be visible, as would the US Bancorp Tower {{convert|536|ft}} and the Wells Fargo Center {{convert|546|ft}}. Newberg’s elevation is {{convert|175|ft}} above sea level, Oregon City {{convert|138|ft}}, McMinnville {{convert|157|ft}}, Salem {{convert|154|ft}}, Corvallis {{convert|235|ft}} and Eugene {{convert|430|ft}}, likely rising above all of them. The lake eventually flowed out and drained, leaving {{convert|180|to|200|ft|m}} of layered sedimentary soils throughout the Tualatin, Yamhill and Willamette valleys.
Name
Geologists named the lake after Oregon State University geologist Ira S. Allison. Among other things, he was the first person to identify and correlate Willamette silt soil in 1953 with soils at the former lake bed of Lake Lewis in eastern Washington. In the 1930s he had documented hundreds of non-native boulders (also known as glacial erratics) that had been transported by the floods on icebergs and had left a ring around the lower hills surrounding the Willamette Valley. The most notable of these is the Bellevue Erratic, off Highway 18 west of McMinnville.
See also
References
{{reflist}}
External links
- {{usurped|1=[https://web.archive.org/web/20080929062024/http://columbiariverimages.com/Regions/Places/missoula_floods.html Missoula Floods information]}} - Columbia River Images
- [http://www.waymarking.com/waymarks/WM19FR Most powerful documented freshwater flood in history] - Waymark
{{Ice Age Floods}}
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