The Hall Lake Formation, formerly called the Hall Lake Member, is a

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...

in Sierra County, New Mexico preserving

Lancian The Lancian was a North American faunal stage of the Late Cretaceous. It was the final stage of the Cretaceous period in North America, lasting from approximately 70.6 to 66 million years ago. Geology Terrestrial sedimentary strata from the Judit ...

fauna, most notably

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

s. It is regarded as a member of the

McRae Group The McRae Group is a geological Group (stratigraphy), group exposed in southern New Mexico whose strata, including layers of the Hall Lake Formation and Jose Creek Formation, date to the Late Cretaceous. Dinosaur remains are among the fossils th ...

, including the Elephant Butte and Staton-LaPoint locales.Vigla Formation
at Paleobiodb.org

Description

While most estimates place it firmly within the

fauna, specifically using taxa such as ''

Compsemys ''Compsemys '' is an extinct genus of prehistoric turtles from the Late Cretaceous and Paleocene of North America and possibly Europe. The type species ''C. victa'', first described by Joseph Leidy from the Hell Creek Formation in Montana in 1856 ...

'' as index fossils to recover a Campanian-Maastrichtian age, Lozinsky ''et al.'' (1984) note the presence of basalt flows and alluvium dating to the Quaternary-Tertiary. It overlooks the Jose Creek Member and is composed of purple and maroon

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

s. When they meet, it is marked by a basal conglomerate or a color distinction where conglomerate is absent. Various

Cenozoic The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three g ...

units overly the formation. Where some choose to classify these layers as a

member Member may refer to: * Military jury, referred to as "Members" in military jargon * Element (mathematics), an object that belongs to a mathematical set * In object-oriented programming, a member of a class ** Field (computer science), entries in ...

of the

McRae Formation The McRae Group is a geological group exposed in southern New Mexico whose strata, including layers of the Hall Lake Formation and Jose Creek Formation, date to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovere ...

, others classify it as a distinct formation in a

group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic iden ...

of formations.

Fossil content

Dinosaurs

Saurischians

Ornithischians

Reptiles

Plants

References

{{Reflist Cretaceous formations of New Mexico Maastrichtian Stage of North America Sandstone formations of the United States Shale formations of the United States Mudstone formations of the United States Paleontology in New Mexico