Ringold Formation#Landslides

During the flood basalt eruptions before the sediments were laid down, the Columbia River followed a different route than it does today, taking it near the present-day sites of Yakima and Goldendale. North-to-south compression of the Columbia Plateau caused anticline folds like Rattlesnake Mountain and the Horse Heaven Hills to rise.

These ridges provided geographic barriers, rerouting the river eastward toward the Tri-Cities with it eventually flowing through Wallula Gap. During part of this period, the Columbia River was completely dammed leading to the development of a large lake covering the Yakima Valley and southern Columbia Basin. The Ringold Formation is the sediment laid down during the period of the lake's existence and while the route of the river was changing.{{Cite journal |last=Staisch |first=Lydia M. |last2=O'Connor |first2=Jim E. |last3=Cannon |first3=Charles M. |last4=Holm-Denoma |first4=Chris |last5=Link |first5=Paul K. |last6=Lasher |first6=John |last7=Alexander |first7=Jeremy A. |date=2021 |title=Major reorganization of the Snake River modulated by passage of the Yellowstone Hotspot |url=https://www.geology.cwu.edu/facstaff/nick/g351/2021_Staisch_SnakeYHS%20copy.pdf |journal=GSA Bulletin |publisher=Geological Society of America}}

Some of the sediments found as part of the formation may have been sourced from ancestral versions of other Pacific Northwest rivers like the Clearwater and Pend Oreille. Layers of volcanic ash can also be found, with thicknesses ranging from being barely noticeable to {{convert|4|ft|m}} thick.{{cite web|url=https://file.dnr.wa.gov/publications/ger_reprint1_ringold_formation.pdf |title=RINGOLD FORMATION OF PLEISTOCENE AGE IN TYPE LOCALITY, THE WHITE BLUFFS, WASHINGTON |author=R. C. Newcomb |publisher=Washington State Department of Natural Resources |date=1958 |accessdate=2019-12-20}}

The Ringold Formation represents sand and gravel placed by the Columbia River between 9 and 3 million years ago. These deposits overlay cooled lava erupted as part of the Columbia River Basalt Group, a type of volcanic eruption known as flood basalts erupting from fissures across eastern Washington and Oregon that were unrelated to the Cascade Range.{{cite web|url=https://volcanoes.usgs.gov/observatories/cvo/cvo_columbia_river_basalt.html | title=Columbia River Basalt Group Stretches from Oregon to Idaho |publisher=United States Geological Survey |accessdate=2019-12-19}} It is covered in places by deposits from the Missoula Floods.

Regional uplift caused the Columbia to erode parts of the Ringold Formation. The White Bluffs on the Hanford Reach National Monument is a significant example of this.

File:Hanford Reach Sand Dune.jpgLandslides along the Columbia River have increased in recent years due to irrigation around Basin City and Othello. Irrigation water enters and flows through the groundwater system toward the river easily through deposits left by the Missoula Floods. This destabilizes Ringold Formation features like the White Bluffs, causing the landslides.{{cite web|url=https://www.visitthereach.org/a-geological-paradise/ |archive-url=https://web.archive.org/web/20191220053833/https://www.visitthereach.org/a-geological-paradise/ |url-status=usurped |archive-date=December 20, 2019 |title=A Geological Paradise |publisher=Reach Museum |accessdate=2019-12-19}} Landslides did not occur frequently before 1960. Rapid changes in river flow caused by the Priest Rapids Dam upstream may also contribute to slope destabilization.

The largest landslide in the White Bluffs portion of the formation is adjacent to Locke Island. This complex, initiated in the 1970s, has rerouted the Columbia River. As a result of the change, critical salmon spawning habitat has been destroyed. The landslide restricts the flow of the river on the east side of the river and as a result, large portions of Locke Island are being removed by the Columbia River. Movement of this landslide is ongoing, but the primary factor behind the continued movement is destabilization by the Columbia River eroding the fallen material. Blown sand from this landslide is the primary source material for sand dunes atop the bluffs near the island.{{cite web|url=https://www.pnnl.gov/main/publications/external/technical_reports/PNNL-15941.pdf |title=Past, Present, Future Erosion at Locke Island |author=B. N. Bjornstad |publisher=Pacific Northwest National Laboratory |date=2006 |accessdate=2019-12-20}}

The Locke Island slide is the northernmost slide along the White Bluffs. There are at least five other major slides into the Columbia River, with the southernmost one being across the river from Pacific Northwest National Laboratory in north Richland, which occurred in 2008. At least one slide has occurred in nearby coulees.{{cite web|url=https://12c2f97e-e9de-9620-eeb5-c0d53388ee06.filesusr.com/ugd/12afd0_7660a9179e4731665eb815ae8ce92c95.pdf |title=Hydrogeologic Controls and Impacts of Quaternary Landslides Along the White Bluffs of the Columbia River, South-Central Washington |author1=Bruce N. Bjornstad |author2=Robert E. Peterson |publisher=Pacific Northwest National Laboratory |accessdate=2019-12-20}}

The sediments include fossils from the Miocene. Along the Columbia River, fossilized remains of rhinoceros and salmonoid fish. The largest diversity of remains have been found among the White Bluffs, which are an exposed portion of the uppermost part of the formation. In addition to those that were discovered along the river, there are 27 additional species. These include smaller animals such as frogs, lizards, and ring-tailed cats, as well as larger ones like horses, mastodons, and camels. Petrified wood can be found nearby. Analysis of late Miocene to early Pliocene fossils of ringtails suggests the area was once a much milder, but seasonal climate.{{Cite journal|last=Gustafson|first=Eric Paul|date=May 2015|title=Bassariscus from the Early Pliocene of Washington|url=https://bioone.org/journals/Northwest-Science/volume-89/issue-2/046.089.0204/Bassariscus-from-the-Early-Pliocene-of-Washington/10.3955/046.089.0204.full|journal=Northwest Science|volume=89|issue=2|pages=129–135|doi=10.3955/046.089.0204|issn=0029-344X|url-access=subscription}}

Several unique specimens have been found in the formation. An excavation done for a basement near Badger Mountain in Richland unearthed the northwesternmost example found thus far of Aphelops. This is also the only confirmed specimen of Aphelops in Washington.{{cite web|url=https://bioone.org/journals/Journal-of-Vertebrate-Paleontology/volume-32/issue-3/02724634.2012.658481/New-Records-of-Rhinoceroses-from-the-Ringold-Formation-of-Central/10.1080/02724634.2012.658481.short |title=New Records of Rhinoceroses from the Ringold Formation of Central Washington and the Hemphillian-Blancan Boundary |author=Eric P. Gustafson |publisher=Journal of Vertebrate Paleontology |date=2012-05-01 |accessdate=2019-12-19}}

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Category:Columbia River

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