| Favret Formation | |
|---|---|
| Stratigraphic range:Triassic | |
| Type | Geological formation |
| Unit of | Augusta Sequence |
| Lithology | |
| Primary | Limestone |
| Other | Shale,siltstone |
| Location | |
| Region | Nevada |
TheFavret Formation is aTriassic geologicformation. The Favret outcrops in theAugusta,New Pass andFish Creek ranges of north centralNevada and consists oflimestone,shale andsiltstone.[1]
The Favret Formation along with thePrida Formation, constitute one of the recognizedgeological formations within theStar Peak Group of northwestern Nevada. These two formations are linked by a singlemember, known as theFossil Hill Member. In the Prida Formation, this member outcrops in the westernHumboldt Range, while the Favret Formation,outcrops in the Augusta Mountains, where it reaches up to more than 300 metres (980 ft) thick. Although they overlap substantially, the two formations do not share precisely the same age, the Prida unit dates from the Middle to LateAnisian, while the Favret unit dates only from the Late Anisian, between approximately 244 and 242 million years ago.[2]
The Fossil Hill Member has received extensive interest from paleontological research for its large quantity of marine fossils dating from theMiddle Triassic. The paleoenvironment preserved in the Fossil Hill contains some of the earliestmarine reptile communities includingIchthyosaurs andPistosaurs. Other fossils from this unit include invertebrates such asceratitid ammonoids andbivalves as well ashybodont sharks andbony fish likeSaurichthyes andBirgeria.
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