The Wasatchian North American Stage on the
geologic timescale
The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geoch ...
is the North American
faunal stage according to the
North American Land Mammal Ages
The North American land mammal ages (NALMA) establishes a geologic timescale for North American fauna beginning during the Late Cretaceous and continuing through to the present. These periods are referred to as ages or intervals (or stages when re ...
chronology (NALMA), typically set from 55,400,000 to 50,300,000 years
BP lasting .
Paleobiology Database, Wasatchian
/ref>
It is usually considered to be within the Eocene
The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...
, more specifically the Early Eocene
In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...
.
The Wasatchian is preceded by the Clarkforkian
The Clarkforkian North American Stage, on the geologic timescale, is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 56,800,000 to 55,400,000 years BP lasting .
Considered ...
and followed by the Bridgerian NALMA stages.
Definition
The age is named after the Wasatch Formation, a highly fossiliferous stratigraphic unit stretching across six of the United States from Idaho
Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and W ...
and Montana
Montana () is a U.S. state, state in the Mountain states, Mountain West List of regions of the United States#Census Bureau-designated regions and divisions, division of the Western United States. It is bordered by Idaho to the west, North ...
in the north through Utah
Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...
and Wyoming
Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to the sou ...
to Colorado
Colorado (, other variants) is a state in the Mountain states, Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the wes ...
and New Mexico
)
, population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano)
, seat = Santa Fe, New Mexico, Santa Fe
, LargestCity = Albuquerque, New Mexico, Albuquerque
, LargestMetro = Albuquerque metropolitan area, Tiguex
, Offi ...
in the south.
Substages
The Wasatchian is considered to contain the following substages:
* Sandcouleean: shares lower boundary with the beginning of the Wasatchian age and shares upper boundary with the base of the Graybullian.
* Graybullian: shares lower boundary with the end of the Sandcouleean subage and upper boundary with the base of the Lysitean.
* Lysitean: shares lower boundary with the end of the Graybullian subage and upper boundary with the base of the Lostcabinian.
* Lostcabinian: shares lower boundary with the end of the Lysitean subage and upper boundary with the beginning of the Bridgerian.
Wasatchian correlations
References
Eocene life
Eocene animals of North America
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