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Alkali Canyon Formation

Coordinates: 45°42′N 120°12′W / 45.7°N 120.2°W / 45.7; -120.2
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Alkali Canyon Formation
Stratigraphic range: Tortonian-Zanclean (Hemphillian)
~10.3–4.9 Ma
TypeFormation
Unit ofDalles Group
OverliesColumbia River Basalt Group
Lithology
PrimarySandstone
OtherTuff
Location
Coordinates45°42′N 120°12′W / 45.7°N 120.2°W / 45.7; -120.2
Approximate paleocoordinates45°36′N 117°30′W / 45.6°N 117.5°W / 45.6; -117.5
RegionGilliam & Morrow Counties, Oregon
Country United States
ExtentEastern Columbia Basin
Type section
Named forAlkali Canyon, 16 km (9.9 mi) SW of Arlington
Named byFarooqui et al.
Year defined1981
Alkali Canyon Formation is located in the United States
Alkali Canyon Formation
Alkali Canyon Formation (the United States)
Alkali Canyon Formation is located in Oregon
Alkali Canyon Formation
Alkali Canyon Formation (Oregon)

The Alkali Canyon Formation is a geologic formation in Oregon. It preserves fossils dating back to the Tortonian to Zanclean stages (Hemphillian) of the Neogene period.[1][2] It is confined to the Arlington basin, and is named after Alkali Canyon, a canyon 16 km southwest of Arlington, Oregon.[3] It was formally defined in 1981 along with the Chenoweth, Tygh Valley, Deschutes, and McKay formations, many of which have historically been called the Dalles Formation.[3] The Arlington basin is filled mainly with epiclastic sediment, derived from fragments of volcanic rock, from the northern flank of the Blue Mountains. The Alkali Canyon Formation is composed of basalt gravel and tuffaceous sediment.[3] The Alkali Canyon Formation overlies the Columbia River Basalt Group, a layer of flood basalt from the middle to late Miocene.[3][better source needed] It underlies mainly Quaternary loess.[4]

The Arlington basin the formation is located in is bordered by the Columbia Hills anticline on the north, the Service anticline on the east, the Blue Mountains on the south, and by basalt upland to the west.[3]

See also

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References

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  1. ^ Alkali Canyon Formation at Fossilworks.org
  2. ^ Alkali Canyon Formation at USGS
  3. ^ a b c d e Farooqui, Saleem M (October 1981). "Dalles Group: Neogene formations overlying the Columbia River Basalt Group in north-central Oregon" (PDF). Oregon Geology. Vol. 43, no. 10. p. 131. ISSN 0164-3304. Retrieved 25 June 2024.
  4. ^ "Geolex — Significant Publications: Geologic Unit: Alkali Canyon". National Geologic Map Database. Retrieved 2024-07-09.

Bibliography

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