The Moreno Hill Formation is a geological

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 secondary ...

in western

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...

whose strata were deposited in the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

. Dinosaur remains are among the fossils that have been recovered from the formation.Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Cretaceous, North America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 574-588. .

Description

The formation is a nonmarine

coal Coal is a combustible black or brownish-black sedimentary rock, formed as stratum, rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen ...

-bearing formation composed mostly of

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

and

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especia ...

with minor

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, ...

. The shales are brownish gray in color, and the sandstones are discontinuous beds of very pale orange to light brown poorly sorted grains that usually show steep

crossbedding In geology, cross-bedding, also known as cross-stratification, is layering within a stratum and at an angle to the main bedding plane. The sedimentary structures which result are roughly horizontal units composed of inclined layers. The original ...

. The sandstones are interpreted as channel or splay deposits in a

fluvial In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluv ...

environment. The shales include thin lenses of bituminous coal, including

tonstein Tonstein (from the German "Ton", meaning clay, plus "Stein", meaning rock) is a hard, compact sedimentary rock that is composed mainly of kaolinite or, less commonly, other clay minerals such as montmorillonite and illite. The clays often are ce ...

s (distinctive thin ash beds). The total maximum thickness is . It overlies the Atarque Sandstone and is in turn overlain by the Fence Lake Formation. The formation is laterally equivalent to the Tres Hermanos Formation, Pescado Tongue of the

Mancos Shale The Mancos Shale or Mancos Group is a Late Cretaceous (Upper Cretaceous) geologic formation of the Western United States. The Mancos Shale was first described by Cross and Purington in 1899 and was named for exposures near the town of Mancos ...

Gallup Sandstone The Gallup Sandstone is a geologic formation in the Gallup-Zuni basin of New Mexico. It preserves fossils dating back to the late Cretaceous period. Description The formation consists of uniform, very well sorted, fine-grained pink to buff sands ...

, and lower Crevasse Canyon Formation. It represents beds southwest of the pinchout of the Pescado Tongue where the Tres Hermanos Formation and Gallup Sandstone are no longer lithologically distinguishable.

Vertebrate paleofauna

The Moreno Hill Formation was originally thought to be devoid of fossils, but it has since yielded a diverse vertebrate paleofauna.

Fish

Dinosaurs

Testudines

History of investigation

The formation was first named by McLellan and coinvestigators in 1983 for exposures around Moreno Hill in the Salt Lake coal field of western New Mexico. The beds were originally mapped as

Mesaverde Group The Mesaverde Group is a Late Cretaceous stratigraphic group found in areas of Colorado, New Mexico, Utah, and Wyoming, in the Western United States. History The Mesaverde Formation was first described by W.H.Holmes in 1877 during the ...

, but were found to be much lower in the

stratigraphic column A stratigraphic column is a representation used in geology and its subfield of stratigraphy to describe the vertical location of rock units in a particular area. A typical stratigraphic column shows a sequence of sedimentary rocks, with the oldest ...

References

{{Reflist Cretaceous formations of New Mexico Turonian Stage