Hall Lake Formation Explained

Hall Lake Formation
Type:	Geological formation
Age:	Late Cretaceous, Campanian–Maastrichtian ~
Period:	Campanian–Maastrichtian
Prilithology:	Mudstone, "shale", sandstone
Region:	New Mexico
Country:	United States
Coordinates:	33.2°N -107.1°W
Paleocoordinates:	40.5°N -81.1°W
Unitof:	McRae Group
Underlies:	Jose Creek Member^[1]
Overlies:	"Quaternary-Tertiary basalt flows and alluvium"

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]

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, 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,^[3] others classify it as a distinct formation in a group of formations.

Fossil content

Dinosaurs

Saurischians

!Genus!Species!Locality!Material!Notes!References!Images

Tyrannosauridae	indet.	Staton-LaPoint	TKM001, dorsal vertebral centrum	Lozinsky et al. (1984) call it indeterminate
Tyrannosaurus	T. mcraeensis	Elephant Butte (upper)	NMMNH P-3698, a partial skull, lower jaw bones, teeth, and chevrons		^[4]
Alamosaurus	sp.	upper	TKM007, a damaged humerus	Tentative referral	^[5]
Sauropoda				Possibly from the Jose Creek Member	^[6]
Theropoda

Ornithischians

Taxon	Locality	Material	Notes	References	Images
Triceratops sp.	2 miles south of Elephant Butte	USNM 243, dorsal vertebral centrum	This genus, Torosaurus or a novel taxon
Sierraceratops turneri	Elephant Butte (lower)	Partial skeleton with skull
Ceratopsidae	Elephant Butte (upper)	TKM002, a coranoid TKM020, crest fragment	A new genus similar to Torosaurus is said to exist above the base of the formation	^[7]
	Elephant Butte (lower)		Indeterminate, in abundance
Torosaurus sp.	Elephant Butte (upper)?
Hadrosauridae	cannot be determined		Indeterminate and of unknown origins due to faulting or Quaternary cover
Ankylosauria		TKM011, pyramidal bone fragment	Possibly from the Jose Creek Member, near identical from UNM-FKK-001P of the Kirtland Formation

Reptiles

Taxon	Locality	Material	Notes	References
Testudinata	Elephant Butte (upper)
Crocodylia
Compsemys			Index fossils suggesting a Lancian age
Bothremydidae

Plants

Genus	Species	Locality	Notes	References
Tracheophyta	indet.	2 miles south of Elephant Butte
Sabalites	sp.		Possibly from the Jose Creek Member
Sequoia
Sabal
Araucarites
Viburnum
Cinnamomum
Exnelumbites
Phyllites
Ficus
Salix

Notes and References

1. Amato . Jeffrey M. . Mack . Greg H. . Jonell . Tara N. . Seager . William R. . Upchurch . Garland R. . 2017-05-11 . Onset of the Laramide orogeny and associated magmatism in southern New Mexico based on U-Pb geochronology . Geological Society of America Bulletin . en . B31629.1 . 10.1130/B31629.1 . 0016-7606.
2. https://paleobiodb.org/classic/displaySearchStrataResults?group_formation_member=Hall%20Lake Vigla Formation
3. Lozinsky . Richard P. . Hunt . Adrian P. . Wolberg . Donald L. . Lucas . Spencer G. . 1984 . Late Cretaceous (Lancian) dinosaurs from the McRae Formation, Sierra County, New Mexico . New Mexico Geology . en . 6 . 4 . 72–77 . 10.58799/NMG-v6n4.72 . 237011797 . 2837-6420.
4. Dalman . Sebastian G. . Loewen . Mark A. . Pyron . R. Alexander . Jasinski . Steven E. . Malinzak . D. Edward . Lucas . Spencer G. . Fiorillo . Anthony R. . Currie . Philip J. . Longrich . Nicholas R. . 2024-01-11 . A giant tyrannosaur from the Campanian–Maastrichtian of southern North America and the evolution of tyrannosaurid gigantism . Scientific Reports . en . 13 . 1 . 22124 . 10.1038/s41598-023-47011-0 . 2045-2322. free . 38212342 . 10784284 .
5. Dalman . Sebastian G. . Lucas . Spencer G. . Jasinski . Steven E. . Longrich . Nicholas R. . 2022 . Sierraceratops turneri, a new chasmosaurine ceratopsid from the Hall Lake Formation (Upper Cretaceous) of south-central New Mexico . Cretaceous Research . en . 130 . 105034 . 10.1016/j.cretres.2021.105034. 2022CrRes.13005034D . 244210664 .
6. "McRae, Sierra County, New Mexico, USA" at mindat.org
7. Lucas . Spencer G. . Dalman . Sebastian . Lichtig . Asher J. . Elrick . Scott . Nelson . W. John . Krainer . Karl . 2017 . Stratigraphy and Age of the Dinosaur-Dominated Fossil Assemblage of the Upper Cretaceous Hall Lake Member of the Mcrae Formation, Sierra County, New Mexico . New Mexico Geological Society Annual Spring Meeting . New Mexico Geological Society, 2017 Annual Spring Meeting, Proceedings Volume, Theme: "Uranium in New Mexico: The Resource and the Legacy" . 10.56577/SM-2017.479. free .