The Purgatoire Formation is an abandoned (1987)
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
period
Period may refer to:
Common uses
* Era, a length or span of time
* Full stop (or period), a punctuation mark
Arts, entertainment, and media
* Period (music), a concept in musical composition
* Periodic sentence (or rhetorical period), a concept ...
geologic
formation
Formation may refer to:
Linguistics
* Back-formation, the process of creating a new lexeme by removing or affixes
* Word formation, the creation of a new word by adding affixes
Mathematics and science
* Cave formation or speleothem, a secondar ...
classification. The classification was used in
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 ...
,
New Mexico
)
, population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano)
, seat = Santa Fe
, LargestCity = Albuquerque
, LargestMetro = Tiguex
, OfficialLang = None
, Languages = English, Spanish ( New Mexican), Navajo, Ke ...
, and
Oklahoma, with mentions in older geologic literature in neighboring states.
[Griggs and Read, 1959.]
Units previously classified as members of the abandoned formation, including
Lytle,
Mesa Rica,
Pajarito,
Romeroville, and
Glencairn, have been generally elevated to formation rank. Particularly, significant divisions of the Purgatoire classification,
Lytle and
Glencairn, were realized as having characteristics of formations in their own right as well as representing the greatest
disconformity
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval ...
in the Lower Cretaceous sediments of the
Western Interior Seaway
The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, and the Western Interior Sea) was a large inland sea that split the continent of North America into two landmasses. The ancient sea ...
. Rather than including these promoted formations in an elevated Purgatoire Group, the Mesa Rica, Pajarito, and Romeroville were placed in a definition of the
Dakota Group
The Dakota is a sedimentary geologic unit name of formation and group rank in Midwestern North America. The Dakota units are generally composed of sandstones, mudstones, clays, and shales deposited in the Mid-Cretaceous opening of the Western ...
local to the
Dry Cimarron.
See also
*
List of fossiliferous stratigraphic units in Colorado
*
Paleontology in Colorado
The location of the state of Colorado
Paleontology in Colorado refers to paleontological research occurring within or conducted by people from the U.S. state of Colorado.
The geologic column of Colorado spans about one third of Earth's history ...
References
Cretaceous Colorado
{{Cretaceous-stub