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The Kirtland Formation (originally the Kirtland Shale) is a
The Kirtland Formation (originally the Kirtland Shale) is a sedimentary
Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...
geological
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other E ...
formation.
Description
The Kirtland Formation is the product of alluvial muds andoverbank
An overbank is an alluvial geological deposit consisting of sediment that has been deposited on the floodplain of a river or stream by flood waters that have broken through or overtopped the banks. The sediment is carried in suspension, and be ...
sand deposits from the many channels draining the coastal plain that existed on the inland seashore of North America, in the late 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. It overlies the Fruitland Formation
The Fruitland Formation is a geologic formation found in the San Juan Basin in the states of New Mexico and Colorado, in the United States of America. It contains fossils dating it to the Campanian age of the late Cretaceous.
. It is found in the San Juan Basin
The San Juan Basin is a geologic structural basin located near the Four Corners region of the Southwestern United States. The basin covers 7,500 square miles and resides in northwestern New Mexico, southwestern Colorado, and parts of Utah ...
in the states of 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 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 ...
, in the United States of America
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territo ...
.
The base of the Kirtland Formation and its lowest sub-unit, the Hunter Wash member, has been dated to 75.02 ± 0.13 Ma. Together with the upper part of the underlying Fruitland Formation
The Fruitland Formation is a geologic formation found in the San Juan Basin in the states of New Mexico and Colorado, in the United States of America. It contains fossils dating it to the Campanian age of the late Cretaceous.
, this contains fossils representing the Hunter Wash local fauna. The border between the Hunter Wash member and overlying Farmington member dates to approximately 74 million years ago. The top of the Farmington member and bottom of the overlying De-na-zin member has been radiometrically dated to 73.83 ± 0.18 Ma ago. The top of the De-na-zin member, which contains the Willow Wash local fauna, has been dated to 73.49 ± 0.25 Ma ago.
Overlying the De-na-zin member is a unit called the Naashoibito member This has often been considered to be part of the Kirtland formation, but more recently has been transferred back to the overlying Ojo Alamo Formation
The Ojo Alamo Formation is a geologic formation in New Mexico spanning the Mesozoic/Cenozoic boundary. Non-avian dinosaur fossils have controversially been identified in beds of this formation dating from after the Cretaceous–Paleogene extinctio ...
, which it had originally been part of.
History of investigation
The formation was named by C.M. Bauer in 1916 for exposures near the Kirtland Post Office.Stratigraphy
Vertebrate paleofauna
Saurischians
Ornithischians
Pterosaurs
Crurotarsans
Turtles
Bony fish
Cartilaginous fish
See also
*List of stratigraphic units with dinosaur body fossils
This is a list of stratigraphic units from which dinosaur body fossils have been recovered. Although Dinosauria is a clade which includes modern birds, this article covers only Mesozoic stratigraphic units. Units listed are all either formation ...
References
Bibliography
* * * * * * * * * * * * * * * {{Chronostratigraphy of Colorado, Mesozoic state=expanded Cretaceous formations of New Mexico 01 Upper Cretaceous Series of North America Campanian Stage Sandstone formations of the United States Shale formations of the United States Mudstone formations Conglomerate formations Deltaic deposits Fluvial deposits