Vester Formation

Geologic formation in Oregon, United States

Vester Formation
Stratigraphic range: Ladinian - Norian
Type	Formation
Unit of	Olds Ferry Terrane
Sub-units	Brisbois Member
Area	Central Oregon
Location
Coordinates	44.118° N, 119.483° W
Region	Oregon
Country	United States

The Vester Formation is a geologic formation in Oregon which preserves fossils dating back to the Triassic period. The partial skeleton of a new genus of basal thalattosaur has been recovered from the Brisbois Member of this formation.^[1] The Brisbois Member, which dates to between the Carnian and Norian, is a marine sequence primarily composed of fine-grained clastic sedimentary rocks with fissile mudstones of black, green or gray variety broken up by widely spaced intervals of calcirudite beds and calcareous conglomerate.^[2] The formation formed between two parallel island arcs, that of the Baker Terrane and the Olds Ferry Terrane. The formation mostly consists of reworked chert grains from the Baker Terrane.^[3] In addition to the remains of the basal thalattosaur, fragmentary and undescribed remains exist of an ichthyosaur, archosaur, and a hybodontid shark as well as many invertebrate fossils.^[1]

References

^ ^a ^b Metz, Eric T. (2019). Description, phylogenetic analysis and taphonomy of a new Thalattosaur from the Brisbois member of the Vester Formation (Carnian/Norian) of central Oregon (ms thesis). University of Alaska Fairbanks.
^ Dickinson and Vigrass, 1965
^ Dorsey and LaMaskin, 2007