Hall Lake Formation
Geologic formation in New Mexico, USA
From Wikipedia, the free encyclopedia
The Hall Lake Formation, formerly called the Hall Lake Member, is a geological formation in Sierra County, New Mexico preserving Lancian fauna, most notably dinosaurs. It is regarded as a member of the McRae Group, including the Elephant Butte and Staton-LaPoint locales.[2]
| Hall Lake Formation | |
|---|---|
| Stratigraphic range: Late Cretaceous, Campanian–Maastrichtian ~ | |
| Type | Geological formation |
| Unit of | McRae Group |
| Underlies | Jose Creek Member[1] |
| Overlies | "Quaternary-Tertiary basalt flows and alluvium" |
| Lithology | |
| Primary | Mudstone, "shale", sandstone |
| Location | |
| Coordinates | 33.2°N 107.1°W |
| Approximate paleocoordinates | 40.5°N 81.1°W |
| Region | New Mexico |
| Country | United States |
  Hall Lake Formation (the United States)  Hall Lake Formation (New Mexico) | |
Description
While most estimates place it firmly within the Lancian fauna, specifically using taxa such as Compsemys as index fossils to recover a Campanian-Maastrichtian age,[3] 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 shales. When they meet, it is marked by a basal conglomerate or a color distinction where conglomerate is absent. Various Cenozoic units overly the formation. Where some choose to classify these layers as a member of the McRae Formation,[4] others classify it as a distinct formation in a group of formations.[5]
Fossil content
Dinosaurs
Saurischians
Color key
|
Notes Uncertain or tentative taxa are in small text; |
| Genus | Species | Locality | Material | Notes | Images |
|---|---|---|---|---|---|
| Tyrannosauridae[4] | indet. | Staton-LaPoint |
|
Lozinsky et al. (1984) call it indeterminate | |
| Tyrannosaurus[6] | T. mcraeensis | Elephant Butte (upper) |
|
 | |
| Alamosaurus[4][5] | sp. | upper |
|
Tentative referral | |
| Sauropoda[7] | Possibly from the Jose Creek Member | ||||
| Theropoda[7] |
Ornithischians
Color key
|
Notes Uncertain or tentative taxa are in small text; |
| Taxon | Locality | Material | Notes | Images |
|---|---|---|---|---|
| Triceratops sp.[2][4] | 2 miles south of Elephant Butte |
|
This genus, Torosaurus or a novel taxon |  |
| Sierraceratops turneri[5] | Elephant Butte (lower) |
|
 | |
| Ceratopsidae[3] | Elephant Butte (upper) |
|
A new genus similar to Torosaurus is said to exist above the base of the formation | |
| Elephant Butte (lower) | Indeterminate, in abundance | |||
| Torosaurus sp.[3] | Elephant Butte (upper)? | |||
| Hadrosauridae[3] | cannot be determined | Indeterminate and of unknown origins due to faulting or Quaternary cover | ||
| Ankylosauria[4][7] |
|
Possibly from the Jose Creek Member, near identical from UNM-FKK-001P of the Kirtland Formation |
Reptiles
Plants
| Genus | Species | Locality | Material | Notes |
|---|---|---|---|---|
| Araucarites[7] | A. sp. | |||
| Cinnamomum[7] | C. sp. | |||
| Exnelumbites[8] | E. morphotype 2 | Leaves | A member of Nelumbonaceae | |
| Ficus[7] | F. sp. | |||
| Phyllites[7] | P. sp. | |||
| Sabal[7] | S. sp. | |||
| Sabalites[7] | S. sp. | |||
| Salix[7] | S. sp. | |||
| Sequoia[7] | S. sp. | |||
| Tracheophyta[2] | Indeterminate | 2 miles south of Elephant Butte | ||
| Viburnum[7] | V. sp. |