The Zuni Sandstone is a

geologic 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 exp ...

in west-central

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, Ker ...

. It marks the southernmost limit of

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

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 fluviog ...

and

lacustrine A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

sedimentary Sedimentary rocks are types of rock (geology), rock that are formed by the accumulation or deposition of mineral or organic matter, organic particles at Earth#Surface, Earth's surface, followed by cementation (geology), cementation. Sedimentati ...

formations, which pinch out to leave a single

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) ...

body.

Description

The Zuni Sandstone is found south of the I-40 corridor in west-central New Mexico. At about this latitude, the Todilto,

Morrison Morrison may refer to: People * Morrison (surname), people with the Scottish surname Morrison * Morrison Heady (1829–1915), American poet * Morrison Mann MacBride (1877–1938), Canadian merchant Places in the United States * Morrison, Colorad ...

, and

Summerville Formation The Summerville Formation is a geological formation in New Mexico, Colorado, and Utah of the Southwestern United States. It dates back to the Oxfordian stage of the Late Jurassic.Wilcox 2007 Description The formation consists of up to of red m ...

s pinch out to leave a Jurassic section that is almost entirely composed of eolian

. This is designated as the Zuni Sandstone, which is thus the lateral equivalent of the combined Entrada and

Bluff Formation The Bluff Formation is a geological formation found in the Four Corners area. It was deposited in the late Jurassic Period (geology), Period. Description The Bluff Formation consists of massive wind-deposited (Aeolian processes, eolian) sandston ...

s. At the type section at Dowa Yalaane (Taaiyalone Mesa), the formation consists of about of eolian sandstone corresponding to the Entrada Formation. A break corresponds to the pinched-out Todilto and Summerville Formations. Above this is about of sandstone corresponding to the Bluff Formation. Then comes a break corresponding to the pinch-out of the Recapture Member of the Morrison Formation, another sandstone interval corresponding to the Acoma Tongue of the Zuni Sandstone, and a final break corresponding to the pinchout of the remaining Morrison Formation. The Zuni Formation

unconformably An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval o ...

rests on the

Wingate Sandstone The Wingate Sandstone is a geologic formation in the Glen Canyon Group of the Colorado Plateau province of the United States which crops out in northern Arizona, northwest Colorado, Nevada, and Utah. Geology Wingate Sandstone is particularly pro ...

or Chinle Group and is unconformably overlain by the

Dakota Formation The Dakota is a sedimentary geologic unit name of formation and group rank in Midwestern North America. The Dakota units are generally composed of sandstones, mudstones, clays, and shales deposited in the Mid-Cretaceous opening of the Western Int ...

History of investigation

The unit was first described by

Clarence Dutton Clarence Edward Dutton (May 15, 1841 – January 4, 1912) was an American geologist and US Army officer. Dutton was born in Wallingford, Connecticut on May 15, 1841. He graduated from Yale College in 1860 and took postgraduate courses there until ...

in 1885. However, A.A. Baker, C.H. Dane, and J.B. Reeside regarded it as identical to the Morrison Formation. R.J. Hackman and A.B. Olson renamed the beds as the Cow Springs Sandstone in 1977 O.J. Anderson proposed the modern definition of the formation in 1983.

References

{{Reflist Jurassic formations of New Mexico Sandstone formations of the United States