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Unalaska Formation

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Unalaska Formation
Stratigraphic range: Miocene Era,
Neogene Period
Outcrops near Dutch Harbor, Unalaska
TypeGeologic formation
OverliesAleutian Ridge
Thickness900–10,000 metres (3,000–32,800 ft)
Location
RegionAleutian Islands,
Alaska
CountryUnited States
Type section
Named forUnalaska Island

The Unalaska Formation is a Miocene Era geologic formation on Amaknak Island and Unalaska Island, in the Aleutian Islands archipelago of southwestern Alaska.[1]

It consists mainly of volcanic breccia, flows, tuff, and intercalated sedimentary rocks.[1] It is exposed over about 70 percent of Unalaska Island. The Dutch Harbor Member is a 126 metres (413 ft) thick Early Miocene sequence of the formation.[1]

It preserves fossils dating back to the Miocene era of the Neogene period.[2]

See also

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References

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  1. ^ a b c USGS: Stratigraphy and depositional environment of the Dutch Harbor Member of the Unalaska Formation, Unalaska Island, Alaska
  2. ^ Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Retrieved 17 December 2021.