The Zia Formation 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 the southwestern

Jemez Mountains The Jemez Mountains are a group of mountains in Rio Arriba, Sandoval, and Los Alamos counties, New Mexico, United States. Numerous Puebloan Indian tribes have lived in the Jemez Mountains region since before the Spanish arrived in New Mexico. T ...

and northwestern Santo Domingo basin. It contains

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...

that date it to early to middle

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

in age.

Description

The Zia Formation is a very soft

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

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) ...

. The type section rests on about of laminated greenish

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

beds that in turn rest on the Galisteo Formation. The upper contact is with the

Cerro Conejo Formation The Cerro Conejo Formation is a middle to late Miocene geologic formation exposed near Albuquerque, New Mexico. Gravel beds within the formation in the Rio Puerco valley west of Albuquerque have provided clues to the paleogeography of the Gr ...

, with the

Cochiti Formation The Cochiti Formation is a geologic formation exposed near the southwest Jemez Mountains of northern New Mexico. Its age is estimated as 10 to 2.6 million years, corresponding to the middle Miocene to Pliocene. Description The formation consist ...

, or with Miocene volcanic rocks of the Jemez volcanic field. The formation is divided (in ascending stratigraphic order) into the Piedra Parada

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 ...

, the Chamisa Mesa Member. and the Canada Pilares Member. The formation is interpreted as eolian deposits derived from volcaniclastics of the

Jemez volcanic field The Jemez Mountains are a group of mountains in Rio Arriba, Sandoval, and Los Alamos counties, New Mexico, United States. Numerous Puebloan Indian tribes have lived in the Jemez Mountains region since before the Spanish arrived in New Mexico. T ...

. These were first transported south by the Jemez River, then transported by wind from the west.

Fossils

The Piera Parada Member contains fossils mostly of camels (''

Stenomylus ''Stenomylus'' is an extinct genus of miniature camelid native to North America that died out around 30 million years ago. Its name is derived from the Greek (, "narrow") and (, "molar"). ''Stenomylus'' was extremely diminutive compared to ...

'', '' Oxydactylus'', and ''

Michenia ''Michenia'' is an extinct genus of camelid endemic to North America. They lived from the Early Miocene to Middle Miocene 20.43—10.3 mya, existing for approximately . Fossil have been found from California to Texas, Alberta, Idaho and Nebraska ...

'') and rhinos (''

Diceratherium ''Diceratherium'' (meaning "two horned beast") is an extinct genus of rhinoceros endemic to North America, Europe, and Asia during the Oligocene through Miocene living from 33.9 to 11.6 mya, existing for approximately . Mass estimates for the ...

''.) These are characteristic of the late Arikareean faunal stage, 22 to 19 million years ago. The Chamisa Mesa Member contains four fossil quarries from which fossils have been found that are characteristic of the Hemingfordian faunal stage, 20.6 to 16.3 million years ago. These include specimens of ''

Menoceras ''Menoceras'' ("Crescent Horns") is a genus of extinct, small rhinoceros endemic to most of southern North America and ranged as far south as Panama during the early Miocene epoch. It lived from around 30.7—19.7 Ma, existing for approximately ...

'', ''

Protolabis ''Protolabis'' is an extinct genus of camelid endemic to North America. It lived from the Early to Late Miocene 20.4—5.3 mya, existing for approximately . Fossil distribution is widespread from Nicaragua, Central America to Montana ...

'', '' Aepycamelus'', '' Subparacosoryx'', ''

Promartes ''Promartes'' is a genus of mustelids, now extinct, which existed during the Miocene period. Taxonomy The genus was first described in 1942, by E. S. Riggs, who identified the sister genus '' Zodiolestes'' at the same time, and assigned to the ...

'', ''

Tomarctus ''Tomarctus'' is a canid genus of the extinct subfamily Borophaginae which inhabited most of North America during the late Early Miocene to the Early Barstovian age of the Middle Miocene (23—16 million years ago). ''Tomarctus'' existed for ...

'', ''

Cynarctoides ''Cynarctoides'' is an extinct genus of the Borophaginae subfamily of canids native to North America. It lived from the Early Oligocene to the Middle Miocene, 33.3—13.6 Mya, existing for approximately . Seven species are currently recognised, a ...

'', and '' Blickomylus''.

History of investigation

The formation was first described by Regan in 1903, who named it the Zia Marl. T. Galusha renamed it the Zia Sand Formation and divided it into the lower Piedra Parada Member and the upper Chamisa Mesa Member. He also recognized a subtle disconformity about 120 m above its base. In 1981, C.E. Gawne assigned a sequence of reddish beds above the Chamisa Mesa Member to the Zia Formation as the Canada Pilares Member. In 1997, R.H. Tedford and Steven Barghoorn added an additional sequence of beds above the Canada Pilares Member to the Zia Formation as the Cerro Conejo Member. However, two years later, they recommended moving this member into its own formation.

Footnotes

References

* * * * * * {{cite journal , last1=Tedford , first1=R.H. , last2=Barghoorn , first2=Steven , year=1999 , title=Santa Fe Group (Neogene), Ceja del Rio Puerco, northwestern Albuquerque basin, Sandoval County, New Mexico , journal=New Mexico Geological Society Field Conference Guidebook , volume=50 , pages=327–336 , url=https://nmgs.nmt.edu/publications/guidebooks/downloads/50/50_p0327_p0335.pdf , access-date=11 August 2020 Neogene formations of New Mexico Neogene stratigraphic units of North America

Description

Fossils

History of investigation

Footnotes

See also

References