# Sentinel Gap

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{{Short description|Water gap in Washington, United States}}
thumb|upright=1.4|Sentinel Gap
thumb|Sentinel Gap Ice Age floods features
'''Sentinel Gap''' is a [water gap](/source/water_gap) formed by the [Columbia River](/source/Columbia_River) in the [Saddle Mountains](/source/Saddle_Mountains), near [Mattawa](/source/Mattawa%2C_Washington) in [Washington](/source/Washington_(state)) state.<ref>{{GNIS|1508220|Sentinel Gap}}</ref> The gap is "a water gap where erosion by the Columbia River was able to keep pace with folding, faulting and uplifting across the Saddle Mountain anticline".{{sfn|Bjornstad|2006|p=242}} During [Ice Age floods](/source/Missoula_Floods) in which waters from the [Channeled Scablands](/source/Channeled_Scablands) found passage to the Pacific Ocean here and at [Wallula Gap](/source/Wallula_Gap),{{sfn|Soehnichsen|2012|pp=154-155}} this opening was "repeatedly reamed out, which probably widened and steepened the walls of the gap".{{sfn|Bjornstad|2006|p=242}} [Strandlines](/source/Strandlines) from the floods can be seen on the basalt walls of the gap.{{sfn|Bjornstad|2006|p=92}}<ref>{{citation|title=Sentinel Gap and Mattawa Bar|date=November 7, 2009|author=Tom Foster|website=Ice Age Floods: Glacial Lake Missoula, Lake Bonneville and the Ice Age Floods|url=http://iceagefloods.blogspot.com/2009/10/sentinel-gap-and-mattawa-bar.html}}</ref>

[SR&nbsp;243](/source/Washington_State_Route_243) runs along the east side of the river through the gap, and the river is spanned by the [Beverly Railroad Bridge](/source/Beverly_Railroad_Bridge).<ref>{{cite news |last=Lindsey |first=Kevin |date=July 25, 1983 |title=Columbia's early course visible at Sentinel Gap |page=D6 |work=[Tri-City Herald](/source/Tri-City_Herald)}}</ref> The gap is located between the [Wanapum](/source/Wanapum_Dam) and [Priest Rapids](/source/Priest_Rapids_Dam) dams. [Priest Rapids](/source/Priest_Rapids), for which the dam was named, are now submerged beneath the dam's reservoir about {{convert|4|miles}} downstream from Sentinel Gap.

==References==
{{reflist}}

==Sources==
*{{citation|title=On the Trail of the Ice Age Floods: A Geological Field Guide to the Mid-Columbia Basin|first=Bruce N. |last=Bjornstad|publisher=Keokee Books|year=2006|ISBN=9781879628274|OCLC=70697754}}
*{{citation|title=Washington's Channeled Scablands Guide|first=John|last=Soehnichsen|ISBN=978-1-59485-483-5|OCLC=910880058|year=2012|publisher=The Mountaineers Books}}

==External links==
*{{Commons category inline|Sentinel Gap}}

{{Washington water gaps}}

{{coord|46|48|19|N|119|56|02|W|type:landmark|display=title}}

Category:Columbia River
Category:Landforms of Kittitas County, Washington
Category:Water gaps of Washington (state)
{{KittitasCountyWA-geo-stub}}

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Adapted from the Wikipedia article [Sentinel Gap](https://en.wikipedia.org/wiki/Sentinel_Gap) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Sentinel_Gap?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.