{{Short description|Lithostratigraphic layer of the Chinle formation}} <!--[[File:Chinle Formation showing each member on a cliff above Capitol Reef Scenic Drive.jpeg|thumb|Chinle Formation section showing each member represented in the Capitol Reef area: Monitor Butte Member (m), the two units of the Petrified Forest Member (p) and the Owl Rock Member (o - partially obscured by overlaying Wingate rubble). [[media:Cliffs along Capitol Reef Scenic Drive-2.jpeg|Non-cropped image]]]]--> {{Infobox rockunit | name = Petrified Forest Member | image = Pf type.jpg | caption = Petrified Forest Member at its type location, north of Tiponi Point, [[Petrified Forest National Park]] | type = [[stratigraphic unit|member]] | age = [[late Triassic]], {{fossil range|240|215}} | period = Norian | prilithology = [[Mudstone]] | otherlithology = [[Sandstone]], [[siltstone]] | namedfor = Petrified Forest, Navajo and Apache Counties, AZ{{sfn|Gregory|1950}} | namedby = [[Herbert E. Gregory]] | year_ts = 1947 | region = [[New Mexico]] | country = [[United States]] | coordinates = {{coord|35.074|N|109.780|W|display:inline}} | unitof = [[Chinle Formation]] | subunits = | underlies = [[Rock Point Formation]] | overlies = [[Poleo Formation]] | thickness = | extent = | area = | map = {{Location map+ | United States#Arizona | relief = 1 | width = 250 | float = center | places = {{Location map~ | United States#Arizona | lat_deg = 35.074 | lon_deg = -109.780 | mark = Purple pog.svg | marksize = 12 }} }} | map_caption = }}
The '''Petrified Forest Member''' is a [[stratigraphic unit]] of the [[Chinle Formation]] in [[Arizona]], [[Colorado]], [[New Mexico]], [[Nevada]], and [[Utah]].{{sfn|GEOLEX|2020}} It preserves [[fossils]] dating back to the [[Triassic]] [[Period (geology)|period]].
==Subunits== Beds (are in alphabetical order, asterisks (*) indicate usage by the U.S. Geological Survey, other usages by state geological surveys<!-- needs to be in time order-->):{{sfn|GEOLEX|2020}} * Capitol Reef Bed (UT*) * Correo Sandstone Bed (NM*) * '''Sonsela Sandstone Bed''' (AZ*,NM*)
In the Chama Basin of New Mexico, the Chinle Formation is promoted to group status and the Petrified Forest Formation has the following members:{{sfn|Lucas|Zeigler|Heckert|Hunt|2005}} * Painted Desert Member * Mesa Montoso Member
The Mesa Montosa Member is up to {{convert|22|meters|feet|abbr=off}} thick and is mostly composed of [[sandstone]] (44%) and [[mudstone]] (35%), with a lesser proportion of [[siltstone]] (20%). The color is reddish brown to brown and the sandstone is thinly bedded and ripple laminated.
The Painted Desert Member is up to {{convert|176|meter|feet|abbr=off}} thick and is primarily reddish brown [[Bentonite|bentonitic]] mudstone. The name was originally applied to the beds above the Sonsela Sandstone Bed in [[Petrified Forest National Park]] in eastern Arizona. Correlative beds of similar lithology are found throughout west-central and central New Mexico and the [[Four Corners]]. The Black Forest Bed within this member has a maximum age of 213 ± 1.7 [[Ma (unit)|Ma]] based on [[detrital zircon geochronology]], with an actual age estimated as 209 Ma. This places the upper part of the Painted Desert Member in the latest [[Norian]] [[Age (geology)|age]].{{sfn|Riggs|Ash|Barth|Gehrels|2003}}
==Fossils== The Snyder quarry, discovered by amateur fossil hunter Mark Snyder near the town of [[Abiquiu, New Mexico]], in 1998, is an unusually productive and diverse bone bed in the Petrified Forest Formation. Abundant charcoal suggests a mass kill due to a paleowildfire. Fossils include [[archosaur]]s, [[procolophonid]]s, [[metoposaurid]] amphibians, [[Semionotiformes|semionotid]] fish, a [[Decapoda|decapod]], a [[conchostracan]], and [[unionid]] bivalves.{{sfn|Zeigler|Heckert|Lucas|2005}}
==See also== {{Portal|Earth sciences|Paleontology}} * [[List of fossiliferous stratigraphic units in New Mexico]] * [[Paleontology in New Mexico]]
==Footnotes== {{reflist}}
==References== * {{cite web |url=https://ngmdb.usgs.gov/Geolex/Units/PetrifiedForest_9600.html|title= Geolex Petrified Forest Member entry|author=<!--Not stated--> |date=24 Sep 2018|website=ngmdb.usgs.gov |publisher=[[U.S. Geological Survey]]|access-date=27 January 2019 |ref={{harvid|GEOLEX|2020}}}} * {{Cite journal |author-link=Herbert E. Gregory |doi=10.3133/PP220 |first=H. E. |issn=0096-0446 |journal=Geological Survey Professional Paper |language=en |last=Gregory |date=1950 |title=Geology and geography of the Zion Park region, Utah and Arizona |url=https://pubs.usgs.gov/pp/0220/report.pdf}} * {{cite journal |last1=Lucas |first1=Spencer G. |author-link1=Spencer G. Lucas |last2=Zeigler |first2=Kate E. |last3=Heckert |first3=Andrew B. |last4=Hunt |first4=Adrian P. |title=Review of Upper Triassic stratigraphy and biostratigraphy in the Chama Basin, northern New Mexico |journal=New Mexico Geological Society Field Conference Series |date=2005 |volume=56 |pages=170-181 |url=https://nmgs.nmt.edu/publications/guidebooks/downloads/56/56_p0170_p0181.pdf |accessdate=29 April 2020}} * {{cite journal |last1=Riggs |first1=N.R. |last2=Ash |first2=S.R. |last3=Barth |first3=A.P. |last4=Gehrels |first4=G.E. |last5=Wooden |first5=J.L. |title=Isotopic age of the Black Forest Bed, Petrified Forest Member, Chinle Formation, Arizona: An example of dating a continental sandstone |journal=Geological Society of America Bulletin |date=2003 |volume=115 |issue=11 |pages=1315 |doi=10.1130/B25254.1}} * {{cite journal |last1=Zeigler |first1=Kate E. |last2=Heckert |first2=Andrew B. |last3=Lucas |first3=Spencer G. |title=Taphonomic analysis of a fire-related Upper Triassic vertebrate fossilassemblage from north-central New Mexico |journal=New Mexico Geological Society Field Conference Series |date=2005 |volume=56 |pages=341-354 |url=https://nmgs.nmt.edu/publications/guidebooks/downloads/56/56_p0341_p0354.pdf |accessdate=25 May 2020}}
[[Category:Triassic geology of New Mexico]] [[Category:Chinle Formation]] [[Category:Mudstone members]] [[Category:Siltstone members]] [[Category:Sandstone members]] [[Category:Geologic members of the United States]]