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{{short description|National park in Arizona, United States}}
{{Infobox protected area
| name            = Petrified Forest National Park
| iucn_category   = II
| iucn_ref        =
<!-- images -->
| photo           = File:Jasper Forest at Petrified Forest NP in AZ 12.jpg
| photo_caption   = Jasper Forest at Petrified Forest NP
| photo_width     = 300
| photo_alt       = Conical rock formations showing horizontal banding in red, white, and shades of grey
<!-- map -->
| map             = USA Arizona inset
| map_image       =
| map_size        =
| map_caption     = Location of Petrified Forest National Park in Arizona. Inset: Arizona in the U.S.
| relief          =
<!-- location -->
| location        = Arizona, United States
| nearest_city    = [[Holbrook, Arizona|Holbrook]]
| nearest_town    =
| coordinates     = {{coord|35|05|17|N|109|48|23|W|display=inline,title}}
| coords_ref      =
<!-- stats -->
| length          =
| length_mi       =
| length_km       =
| width           =
| width_mi        =
| width_km        =
| area_acre       = 221,391
| area_ref        = <ref name="acreage">{{cite web|title=Park Acreage Reports (1997 – Last Calendar/Fiscal Year) |date=September 30, 2019 |publisher=National Park Service, Land Resources Division |page=11 |url=https://www.nps.gov/subjects/lwcf/upload/NPS-Acreage-9-30-2019.pdf |access-date = October 7, 2020 |quote=select 'By Park'/'Fiscal Year'/'2020' in report popup window}}</ref>
| elevation       = {{convert|5436|ft|m|abbr=on}}<ref name="gnis" />
| elevation_avg   =
| elevation_min   =
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| dimensions      =
| designation     =
<!-- dates & info -->
| authorized      =
| created         =
| designated      =
| established     = {{Plainlist|
* 1962 (national park)<ref name="red book" />
* 1906 (national monument)<ref name="NPS history" />
}}
| named_for       = [[Petrified wood]] found in the park
| visitation_num  = 644,922
| visitation_year = 2018
| visitation_ref  = <ref name="visits">{{cite web|title=NPS Stats, Park Reports: PEFO|url=https://irma.nps.gov/Stats/SSRSReports/Park%20Specific%20Reports/Annual%20Park%20Recreation%20Visitation%20%281904%20-%20Last%20Calendar%20Year%29?Park=PEFO|publisher=National Park Service|year=2016|access-date=February 28, 2018}}</ref><ref name="visitation reports">{{NPS visitation |access-date=March 11, 2018}}</ref>
| governing_body  = [[National Park Service]]
| administrator   =
| operator        =
| owner           =
<!-- website, embedded -->
| website         = [https://www.nps.gov/pefo/ Petrified Forest National Park]
| embedded        =
}}

'''Petrified Forest National Park''' is a [[List of national parks of the United States|national park of the United States]] in [[Navajo County, Arizona|Navajo]] and [[Apache County, Arizona|Apache]] counties in northeastern [[Arizona]]. Named for its large deposits of [[petrified wood]], the park covers about {{convert|346|mi2|km2|abbr=off|sp=us}}, encompassing semi-desert shrub [[steppe]] as well as highly eroded and colorful [[badlands]]. The park's headquarters is about {{convert|26|mi|km}} east of [[Holbrook, Arizona|Holbrook]] along [[Interstate 40]] (I-40), which parallels the [[BNSF Railway]]'s [[Southern Transcon]], the [[Puerco River]], and historic [[U.S. Route 66]], all crossing the park roughly east–west. The site, the northern part of which extends into the [[Painted Desert, Arizona|Painted Desert]], was declared a [[National monument (United States)|national monument]] in 1906 and a national park in 1962. The park received 644,922 recreational visitors in 2018.

Averaging about {{convert|5400|ft|m}} in elevation, the park has a dry windy climate with temperatures that vary from summer highs of about {{convert|100|F|C}} to winter lows well below freezing. More than 400 species of plants, dominated by grasses such as [[Tussock (grass)|bunchgrass]], blue grama, and [[Sporobolus|sacaton]], are found in the park. Fauna include larger animals such as [[pronghorn]]s, [[coyotes]], and [[bobcat]]s; many smaller animals, such as [[Peromyscus|deer mice]], snakes, lizards, and seven kinds of [[amphibian]]s; and more than 200 species of birds, some of which are permanent residents and many of which are [[bird migration|migratory]]. About one third of the park is designated [[wilderness]]—{{convert|50260|acres|sqmi km2|0|abbr=on}}.<ref>{{cite web | url = http://www.wilderness.net/index.cfm?fuse=NWPS&sec=wildView&WID=454 | title = Petrified Forest National Wilderness Area | publisher = Wilderness.net | access-date = March 7, 2011 | archive-url = https://web.archive.org/web/20130518222402/http://www.wilderness.net/index.cfm?fuse=NWPS&sec=wildView&WID=454 | archive-date = May 18, 2013  }}</ref>

The Petrified Forest is known for its fossils, especially fallen trees that lived in the [[Late Triassic]] [[Epoch (geology)|Epoch]], about 225&nbsp;million years ago. The sediments containing the fossil logs are part of the widespread and colorful [[Chinle Formation]], from which the Painted Desert gets its name. Beginning about 60&nbsp;million years ago, the [[Colorado Plateau]], of which the park is part, was pushed upward by [[Plate tectonics|tectonic]] forces and exposed to increased erosion. All of the park's rock layers above the Chinle, except geologically recent ones found in parts of the park, have been removed by wind and water. In addition to petrified logs, fossils found in the park have included Late Triassic ferns, [[cycads]], [[ginkgo]]es, and many other plants as well as fauna including giant reptiles called [[phytosaur]]s, large amphibians, and early dinosaurs. [[Paleontology|Paleontologists]] have been unearthing and studying the park's fossils since the early 20th&nbsp;century.

The park's earliest human inhabitants arrived 13,000 years ago.<ref>{{Cite journal |last=HAYNES |first=C. VANCE |date=2011-03-01 |title=Distribution of Clovis Points in Arizona and the Clovis Exploration of the State, 11,000 B.c. |journal=KIVA |volume=76 |issue=3 |pages=343–367 |doi=10.1179/kiv.2011.76.3.004 |s2cid=127475017 |issn=0023-1940}}</ref> These Clovis-era people are the ancestors of Native Americans.<ref>{{Cite journal |last=Wade |first=Lizzie |date=2018-11-09 |title=Ancient DNA tracks migrations around Americas |url=https://www.science.org/doi/10.1126/science.362.6415.627 |journal=Science |language=en |volume=362 |issue=6415 |pages=627–628 |doi=10.1126/science.362.6415.627 |pmid=30409866 |bibcode=2018Sci...362..627W |s2cid=53238432 |issn=0036-8075}}</ref><ref>{{Cite journal |last1=Rasmussen |first1=Morten |last2=Anzick |first2=Sarah L. |last3=Waters |first3=Michael R. |last4=Skoglund |first4=Pontus |last5=DeGiorgio |first5=Michael |last6=Stafford |first6=Thomas W. |last7=Rasmussen |first7=Simon |last8=Moltke |first8=Ida |last9=Albrechtsen |first9=Anders |last10=Doyle |first10=Shane M. |last11=Poznik |first11=G. David |last12=Gudmundsdottir |first12=Valborg |last13=Yadav |first13=Rachita |last14=Malaspinas |first14=Anna-Sapfo |last15=V |first15=Samuel Stockton White |date=February 2014 |title=The genome of a Late Pleistocene human from a Clovis burial site in western Montana |journal=Nature |language=en |volume=506 |issue=7487 |pages=225–229 |doi=10.1038/nature13025 |pmid=24522598 |pmc=4878442 |bibcode=2014Natur.506..225R |issn=1476-4687}}</ref> By about 2,500 years ago Ancestral Pueblo farmers were growing corn and living in subterranean [[Dugout (shelter)|pit houses]] in what would become the park.<ref>{{Cite web |title=Basketmaker II: Birth of Pueblo Culture {{!}} Peoples of Mesa Verde |url=https://www.crowcanyon.org/educationproducts/peoples_mesa_verde/basketmaker_II_overview.asp |access-date=2023-02-11 |website=www.crowcanyon.org}}</ref> By one-thousand years ago Ancestral Pueblo farmers lived in above-ground, masonry dwellings called [[pueblo]]s and gathered in large communal buildings called great kivas.<ref>{{Cite web |last=yongli |date=2016-03-04 |title=Kivas |url=https://coloradoencyclopedia.org/article/kivas |access-date=2023-02-11 |website=coloradoencyclopedia.org |language=en-US}}</ref> By AD 1450 Ancestral Pueblo farmers in the Petrified Forest migrated to join rapidly growing communities on the Hopi Mesas to the northwest and the Pueblo of Zuni to the east–these locations are still home to thousands of descendant community members today.<ref>{{Cite book |last1=Bernardini |first1=Wesley |url=https://books.google.com/books?id=_cYyEAAAQBAJ&dq=becoming+hopi&pg=PP1 |title=Becoming Hopi: A History |last2=Koyiyumptewa |first2=Stewart B. |last3=Schachner |first3=Gregson |last4=Kuwanwisiwma |first4=Leigh J. |date=2021-07-06 |publisher=University of Arizona Press |isbn=978-0-8165-4234-5 |language=en}}</ref> More than 1000 [[archeology|archeological]] sites, including [[petroglyph]]s, have been discovered in the park. These ancestral places remain important to descendant communities. In the 16th&nbsp;century, Spanish explorers visited the area, and by the mid-19th&nbsp;century a U.S. team had surveyed an east–west route through the area where the park is now located and noted the petrified wood.<ref>{{Cite web |last1=Forest |first1=Mailing Address: Petrified Forest National Park P. O. Box 2217 Attn : Petrified |last2=Us |first2=AZ 86028-2217 Phone: 928 524-6228 Contact |title=Explorers and Settlers - Petrified Forest National Park (U.S. National Park Service) |url=https://www.nps.gov/pefo/learn/historyculture/explorerssettlers.htm |access-date=2023-02-11 |website=www.nps.gov |language=en}}</ref> Later, roads and a railway followed similar routes and gave rise to tourism and, before the park was protected, to large-scale removal of fossils. Theft of petrified wood remains a problem in the 21st&nbsp;century.

== Geography ==
[[File:Navajo Reservation, Painted Desert, Petrified Forest National Park, and Adamana AZ aerial.jpg|thumb|Aerial view looking south from the Navajo Reservation (foreground) across the Painted Desert, the Petrified Forest National Park, and Adamana, Arizona]]

Petrified Forest National Park straddles the border between [[Apache County, Arizona|Apache County]] and [[Navajo County, Arizona|Navajo County]] in northeastern Arizona. The park is about {{convert|30|mi|km|-1}} long from north to south, and its width varies from a maximum of about {{convert|12|mi|km|-1}} in the north to a minimum of about {{convert|1|mi|km}} along a narrow corridor between the north and south, where the park widens again to about {{convert|4|to|5|mi|km|0}}.<ref name="DeLorme Arizona" />

[[Interstate 40|I-40]], former [[U.S. Route 66]], the [[BNSF Railway]], and the [[Puerco River]] bisect the park generally east–west along a similar route. [[Adamana, Arizona|Adamana]], a [[ghost town]], is about {{convert|1|mi|km}} west of the park along the BNSF tracks. [[Holbrook, Arizona|Holbrook]], about {{convert|26|mi|km|-1}} west of park headquarters along I-40, is the nearest city.<ref name="DeLorme Arizona" /><ref name="Rand McNally" /> Bisecting the park north–south is Park Road, which runs between I-40 near park headquarters on the north and [[U.S. Route 180]] on the south. Historic Highway&nbsp;180, an earlier alignment of the modern route, crosses the southern edge of the park. Like Route&nbsp;66, it has deteriorated and is closed. Many unpaved maintenance roads, closed to the public, intersect Park Road at various points.<ref name="Part I" />

The fee area of the park owned by NPS covers about {{convert|230|mi2|km2}}.<ref name="acreage"/> The [[Navajo Nation]] borders the park on the north and northeast. State-owned land, federal land controlled by the [[Bureau of Land Management]], and private land, much of it used for cattle ranching, adjoin the other borders. The park's elevation above sea level varies from a low of {{convert|5340|ft|m}} along the Puerco River to a high of {{convert|6230|ft|m}} at Pilot Rock; the average elevation is about {{convert|5,400|ft|sigfig=3}}. The terrain varies from gentle hills and major petrified wood deposits in the south to eroded badlands in the north. Most of the park's intermittent streams—including Lithodendron Wash, Dead Wash, Ninemile Wash, and Dry Wash—empty into the Puerco River. In the southern part of the park, Cottonwood Wash and Jim Camp Wash flow into the [[Little Colorado River]].<ref name="Part I" />

== Geology ==
Petrified Forest National Park is known for its [[fossil]]s, especially of fallen trees that lived in the [[Late Triassic]] Epoch of the [[Mesozoic]] era, about 225-207 million years ago. During this epoch, the region that is now the park was near the equator on the southwestern edge of the supercontinent [[Pangaea]], and its climate was humid and sub-tropical.<ref name="NPS geology" /> What later became northeastern Arizona was a low plain flanked by mountains to the south and southeast and a sea to the west. Streams flowing across the plain from the highlands deposited inorganic sediment and organic matter, including trees as well as other plants and animals that had entered or fallen into the water. Although most organic matter decays rapidly or is eaten by other organisms, some is buried so quickly that it remains intact and may become fossilized.{{sfn|Ash|pp=3–13}} Within the park, the sediments containing the fossil logs for which the park is named are part of the [[Chinle Formation]].<ref name="NPS geology" />

[[File:Painted Desert badlands Tawa Point.jpg|thumb|left|alt=An eroded multi-colored landscape of rounded buttes and small arroyos stretches into the distance under a blank sky.|Painted Desert badlands as seen from the rim at Tawa Point]]

The colorful Chinle, which appears on the surface in many parts of the southwestern United States and from which the [[Painted Desert, Arizona|Painted Desert]] gets its name, is up to {{convert|800|ft|m}} thick in the park.{{sfn|Ash|pp=3–13}} It consists of a variety of [[sedimentary rock]]s including beds of soft, fine-grained [[mudstone]], [[siltstone]], and [[claystone]]—much of which is [[bentonite]]—as well as harder [[sandstone]] and [[conglomerate (geology)|conglomerate]], and [[limestone]].<ref name="NPS geology" />{{sfn|Ash|pp=3–13}} Exposed to wind and water, the Chinle usually [[differential erosion|erodes differentially]] into [[badland]]s made up of cliffs, gullies, [[mesa]]s, [[butte]]s, and rounded hills.{{sfn|Ash|pp=3–13}} Its bentonite clay, which swells when wet and shrinks while drying, causes surface movement and cracking that discourages plant growth. Lack of plant cover makes the Chinle especially susceptible to weathering.<ref name="NPS geology" />

About 60 million years ago, [[Plate tectonics|tectonic]] movements of the Earth's crust began to uplift the [[Colorado Plateau]], of which the Painted Desert is part.<ref name="NPS geology" /> Eventually parts of the plateau rose to {{convert|10000|ft|m}} above sea level.<ref name="NPS geology" /> This warping of the Earth's surface led to the gradual and continuing destruction of the plateau by erosion.<ref>{{Cite journal | last = Walton | first = Matt | title = Geology of the Painted Desert and Petrified Forest | journal = Arizona Highways | volume = XXXIV | issue = 7 | page = 12 | location = Phoenix | date = July 1958 }}</ref> An [[unconformity]] (break in the rock record) of about 200 million years occurs within the park, where erosion has removed all the rock layers above the Chinle except geologically recent ones. The [[Bidahochi Formation]], laid down only 4 to 8 million years ago, rests directly atop the Chinle, and rocks laid down in the [[Jurassic]], [[Cretaceous]], and much of the [[Tertiary]] are absent.<ref name="NPS geology" />

[[File:Blue Mesa Painted Desert.jpg|thumb|right|Painted desert and petrified logs seen from Blue Mesa]]

During the period of the Bidahochi [[deposition (geology)|deposition]], a large lake basin covered much of northeastern Arizona. The older (lower) layers of the formation consist of [[fluvial]] and [[lacustrine plain|lacustrine]] (lake-related) deposits of silt, sand, and clay. The younger (upper) Bidahochi contains ash and [[lava]] from volcanoes that erupted nearby and as far away as southwestern Nevada.<ref name="NPS geology" /> Although much of the Bidahochi has since eroded, a small part of it outcrops in the northern part of the park—on Pilot Rock in the park's wilderness section and along the rim of the Painted Desert between Pintado and Tawa points.{{sfn|Ash|pp=3–13}} Exposed by erosion of the Bidahochi are volcanic landforms called [[maar]]s (flat-bottomed, roughly circular volcanic craters of explosive origin). A maar vent can be seen from the Pintado Point lookout.<ref name="NPS geology" />

During the [[Quaternary Period]] (2.6 million years ago up to today), deposits of windblown sand and [[alluvium]] covered much of the Chinle and Bidahochi. Older dunes range in age from 500,000 years at higher elevations in the northern part of the park to about 10,000 years in sandy drainage areas such as Lithodendron Wash. Stabilized by grasses and other vegetation, young dunes of about 1,000 years old are found throughout the park.<ref name="NPS geology" />

=== Fossils ===
[[Image:Fossilized wood at Petrified Forest.jpg|thumb|left|alt=End-on view of a large reddish log in an eroded landscape|A petrified log in the Petrified Forest]]
During the Late Triassic, downed trees accumulating in river channels in what became the park were buried periodically by sediment containing [[volcanic ash]]. Groundwater dissolved [[silica]] (silicon dioxide) from the ash and carried it into the logs, where it formed [[quartz]] crystals that gradually replaced the organic matter. Traces of [[iron oxide]] and other substances combined with the silica to create varied colors in the petrified wood.<ref name="NPS stone trees" />
[[File:Afternoon at Agate Bridge.jpg|thumb|left|Agate Bridge, a fossilized tree.]]

In Petrified Forest National Park, most of the logs in the park retained their original external form during [[petrifaction|petrification]] but lost their internal structure. However, a small fraction of the logs and most of the park's petrified animal bones have [[Cell (biology)|cells]] and other spaces that are mineral-filled but still retain much of their original organic structure. With these [[permineralization|permineralized]] fossils, it is possible to study the cellular make-up of the original organisms with the aid of a microscope. Other organic matter—typically leaves, seeds, pine-cones, pollen grains, [[spore]]s, small stems, and fish, insect, and animal remains—have been preserved in the park as [[compression fossil]]s, flattened by the weight of the sediments above until only a thin film remains in the rock.{{sfn|Ash|p=11}}
[[File:Petrified Forest SW01.jpg|thumb|Petrified tree – fractured into segments]]
[[Image:Triassic animals from Arizona.jpg|thumb|Reconstructed Triassic skeletons found at Petrified Forest]]
Much of the park's petrified wood is from ''[[Araucarioxylon arizonicum]]'', an extinct [[conifer]] tree, while some found in the northern part of the park is from ''Woodworthia arizonica'' and ''Schilderia adamanica'' trees. At least nine species of fossil trees from the park have been identified; all are extinct. The park has many other kinds of fossils besides trees. The Chinle, considered to be one of the richest Late Triassic fossil-plant deposits in the world, contains more than 200 fossil plant [[taxon|taxa]]. Plant groups represented in the park include [[lycophyte]]s, [[fern]]s, [[cycad]]s, conifers, [[ginkgo]]es, as well as unclassified forms.<ref name="NPS stone trees" /> The park has also produced one of the most diverse assemblages of fossil [[vertebrate]]s from the Late Triassic. Among the groups represented are early theropod dinosaurs,<ref name=":0">{{Cite journal |last1=Long |first1=Robert A. |last2=Murry |first2=Philip A. |date=1995 |title=Late Triassic (Carnian and Norian) Tetrapods from the Southwestern United States |url=https://books.google.com/books?id=wbv9CQAAQBAJ&pg=PP1 |journal=New Mexico Museum of Natural History and Science Bulletin |volume=4 |pages=1–254 |via=Google Books}}</ref><ref>{{Cite journal |last1=Parker |first1=William G. |last2=Irmis |first2=Randall B. |last3=Nesbitt |first3=Sterling J. |date=2006 |title=Review of the Late Triassic Dinosaur Record from Petrified Forest National Park, Arizona |journal=Museum of Northern Arizona Bulletin |volume=62 |pages=160–161}}</ref> crocodile-line archosaurs,<ref>{{Cite journal |last=Parrish |first=J. Michael |date=1991-06-20 |title=A new specimen of an early crocodylomorph (cf. Sphenosuchus sp.) from the Upper Triassic Chinle Formation of Petrified Forest National Park, Arizona |journal=Journal of Vertebrate Paleontology |volume=11 |issue=2 |pages=198–212 |doi=10.1080/02724634.1991.10011387 |bibcode=1991JVPal..11..198P |issn=0272-4634}}</ref><ref>{{Cite journal |last1=Parker |first1=William G |last2=Irmis |first2=Randall B |last3=Nesbitt |first3=Sterling J |last4=Martz |first4=Jeffrey W |last5=Browne |first5=Lori S |date=2005-05-07 |title=The Late Triassic pseudosuchian Revueltosaurus callenderi and its implications for the diversity of early ornithischian dinosaurs |journal=Proceedings of the Royal Society B: Biological Sciences |volume=272 |issue=1566 |pages=963–969 |doi=10.1098/rspb.2004.3047 |pmid=16024353 |pmc=1564089 |issn=0962-8452}}</ref><ref name=":1">{{Cite journal |last=STOCKER |first=MICHELLE R. |date=2010-09-16 |title=A new taxon of phytosaur (Archosauria: Pseudosuchia) from the Late Triassic (Norian) Sonsela Member (Chinle Formation) in Arizona, and a critical reevaluation of Leptosuchus Case, 1922 |journal=Palaeontology |volume=53 |issue=5 |pages=997–1022 |doi=10.1111/j.1475-4983.2010.00983.x |s2cid=83536253 |issn=0031-0239|doi-access=free |bibcode=2010Palgy..53..997S }}</ref><ref>{{Cite journal |last=Parker |first=William G. |date=2016-08-30 |title=Osteology of the Late Triassic aetosaur Scutarx deltatylus (Archosauria: Pseudosuchia) |journal=PeerJ |language=en |volume=4 |pages=e2411 |doi=10.7717/peerj.2411 |issn=2167-8359 |pmc=5012282 |pmid=27635359 |doi-access=free }}</ref><ref>{{Cite journal |last1=Reyes |first1=William A. |last2=Parker |first2=William G. |last3=Marsh |first3=Adam D. |date=2020-12-10 |title=Cranial anatomy and dentition of the aetosaur Typothorax coccinarum (Archosauria: Pseudosuchia) from the Upper Triassic (Revueltian–mid Norian) Chinle Formation of Arizona |journal=Journal of Vertebrate Paleontology |volume=40 |issue=6 |pages=e1876080 |doi=10.1080/02724634.2020.1876080 |bibcode=2020JVPal..40E6080R |s2cid=233616969 |issn=0272-4634}}</ref><ref>{{Cite journal |last1=Parker |first1=William G. |last2=Nesbitt |first2=Sterling J. |date=2013 |title=Cranial remains ofPoposaurus gracilis(Pseudosuchia: Poposauroidea) from the Upper Triassic, the distribution of the taxon, and its implications for poposauroid evolution |journal=Geological Society, London, Special Publications |volume=379 |issue=1 |pages=503–523 |doi=10.1144/sp379.3 |bibcode=2013GSLSP.379..503P |s2cid=85729432 |issn=0305-8719}}</ref> temnospondyl amphibians,<ref>{{Cite journal |last1=Hunt |first1=Adrian P. |last2=Lucas |first2=Spencer G. |date=1993 |title=Taxonomy and Stratigraphic Distribution of Late Triassic Metoposaurid Amphibians from Petrified Forest National Park, Arizona |journal=Journal of the Arizona-Nevada Academy of Science |volume=27 |issue=1 |pages=89–96 |jstor=40023709 |issn=0193-8509}}</ref><ref>{{Cite journal |last1=Gee |first1=Bryan M. |last2=Parker |first2=William G. |date=2018-01-01 |title=A large-bodied metoposaurid from the Revueltian (late Norian) of Petrified Forest National Park (Arizona, USA) |journal=Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen |volume=287 |issue=1 |pages=61–73 |doi=10.1127/njgpa/2018/0706 |issn=0077-7749}}</ref><ref>{{Cite journal |last1=Gee |first1=Bryan M. |last2=Parker |first2=William G. |date=2018-06-07 |title=Morphological and histological description of small metoposaurids from Petrified Forest National Park, AZ, USA and the taxonomy of Apachesaurus |journal=Historical Biology |volume=32 |issue=2 |pages=203–233 |doi=10.1080/08912963.2018.1480616 |s2cid=89662443 |issn=0891-2963}}</ref> lissamphibians,<ref>{{Cite journal |last1=Stocker |first1=Michelle R. |last2=Nesbitt |first2=Sterling J. |last3=Kligman |first3=Ben T. |last4=Paluh |first4=Daniel J. |last5=Marsh |first5=Adam D. |last6=Blackburn |first6=David C. |last7=Parker |first7=William G. |date=2019 |title=The earliest equatorial record of frogs from the Late Triassic of Arizona |journal=Biology Letters |volume=15 |issue=2 |page=20180922 |doi=10.1098/rsbl.2018.0922 |pmid=30958136 |pmc=6405462 |issn=1744-9561}}</ref><ref name=":2">{{Cite journal |last1=Kligman |first1=Ben T. |last2=Gee |first2=Bryan M. |last3=Marsh |first3=Adam D. |last4=Nesbitt |first4=Sterling J. |last5=Smith |first5=Matthew E. |last6=Parker |first6=William G. |last7=Stocker |first7=Michelle R. |date=February 2023|title=Triassic stem caecilian supports dissorophoid origin of living amphibians |journal=Nature |language=en |volume=614 |issue=7946 |pages=102–107 |doi=10.1038/s41586-022-05646-5 |issn=1476-4687 |pmc=9892002 |pmid=36697827|bibcode=2023Natur.614..102K }}</ref> non-archosauromorph diapsids,<ref>{{Cite journal |last1=Kligman |first1=Ben |last2=Marsh |first2=Adam |last3=Parker |first3=William |date=2018 |title=First records of diapsid Palacrodon from the Norian, Late Triassic Chinle Formation of Arizona, and their biogeographic implications |journal=Acta Palaeontologica Polonica |volume=63 |doi=10.4202/app.00426.2017 |s2cid=56558390 |issn=0567-7920|doi-access=free }}</ref><ref name=":3">{{Cite journal |last1=Gonçalves |first1=Gabriel S. |last2=Sidor |first2=Christian A. |date=2019-12-15 |title=A new drepanosauromorph, ''Ancistronychus paradoxus'' n. gen. et sp., from the Chinle Formation of Petrified Forest National Park, Arizona, USA |journal=PaleoBios |volume=36 |doi=10.5070/p9361046203 |s2cid=210142302 |issn=2373-8189|doi-access=free }}</ref> and other dinosauromorphs<ref>{{Cite journal |last1=Marsh |first1=Adam D. |last2=Parker |first2=William G. |last3=Langer |first3=Max C. |last4=Nesbitt |first4=Sterling J. |date=2019-05-04 |title=Redescription of the holotype specimen of Chindesaurus bryansmalli Long and Murry, 1995 (Dinosauria, Theropoda), from Petrified Forest National Park, Arizona |journal=Journal of Vertebrate Paleontology |volume=39 |issue=3 |pages=e1645682 |doi=10.1080/02724634.2019.1645682 |bibcode=2019JVPal..39E5682M |s2cid=202865005 |issn=0272-4634}}</ref><ref>{{Cite journal |last1=Marsh |first1=Adam D. |last2=Parker |first2=William G. |date=2020-11-12 |title=New dinosauromorph specimens from Petrified Forest National Park and a global biostratigraphic review of Triassic dinosauromorph body fossils |journal=PaleoBios |volume=37 |doi=10.5070/p9371050859 |s2cid=228865377 |issn=2373-8189|doi-access=free }}</ref> and archosauromorphs.<ref name=":4">{{Cite journal |last1=Kligman |first1=Ben T. |last2=Marsh |first2=Adam D. |last3=Nesbitt |first3=Sterling J. |last4=Parker |first4=William G. |last5=Stocker |first5=Michelle R. |date=2020-03-26 |title=New trilophosaurid species demonstrates a decline in allokotosaur diversity across the Adamanian-Revueltian boundary in the Late Triassic of western North America |journal=Palaeodiversity |volume=13 |issue=1 |page=25 |doi=10.18476/pale.v13.a3 |s2cid=216308379 |issn=1867-6294|doi-access=free }}</ref><ref>{{Cite journal |last1=Parker |first1=William G. |last2=Nesbitt |first2=Sterling J. |last3=Marsh |first3=Adam D. |last4=Kligman |first4=Ben T. |last5=Bader |first5=Kenneth |date=2021-05-04 |title=First occurrence of Doswellia cf. D. kaltenbachi (Archosauriformes) from the Late Triassic (middle Norian) Chinle Formation of Arizona and its implications on proposed biostratigraphic correlations across North America during the Late Triassic |journal=Journal of Vertebrate Paleontology |volume=41 |issue=3 |doi=10.1080/02724634.2021.1976196 |bibcode=2021JVPal..41E6196P |s2cid=243474578 |issn=0272-4634}}</ref> [[Dicynodont]]s are extremely rare despite being abundantly represented at the ''Placerias'' Quarry near [[St. Johns, Arizona|St. Johns]].<ref name=":0" /><ref name=":6">{{Cite journal |last1=Parker |first1=William G. |last2=Martz |first2=Jeffrey W. |date=2010 |title=The Late Triassic (Norian) Adamanian–Revueltian tetrapod faunal transition in the Chinle Formation of Petrified Forest National Park, Arizona |journal=Earth and Environmental Science Transactions of the Royal Society of Edinburgh |volume=101 |issue=3–4 |pages=231–260 |doi=10.1017/s1755691011020020 |bibcode=2010EESTR.101..231P |s2cid=140536630 |issn=1755-6910}}</ref> Fossil [[invertebrate]]s include freshwater [[snail]]s and [[clam]]s.{{sfn|Ash|pp=25–27}} The oldest fossil [[crayfish]], ''Enoploclytia porteri'', was also described from the park,<ref name=":5">{{Cite journal |last1=Miller |first1=Gary L. |last2=Ash |first2=Sidney R. |date=1988 |title=The oldest freshwater decapod crustacean, from the Triassic of Arizona |url=https://www.palass.org/sites/default/files/media/publications/palaeontology/volume_31/vol31_part2_pp273-279.pdf |journal=Palaeontology |volume=31 |pages=273–279}}</ref> although it is not considered a crayfish proper (instead placed in [[Erymidae]]).

New animal species that were first identified from localities within the current park boundaries, some of which remain known only from the park, are listed below.
{| class="wikitable"
|+
!Clade
!Taxon
!Authority
!Publication year
|-
|Gymnophionomorpha
|''[[Funcusvermis gilmorei]]''
|Kligman, Gee, Marsh, Nesbitt, Smith, Parker, & Stocker<ref name=":2" />
|2023
|-
|[[Aetosaur]]ia
|''[[Kryphioparma caerula]]''
|Reyes, Parker & Heckert<ref>{{Cite journal |last1=Reyes |first1=William A. |last2=Parker |first2=William G. |last3=Heckert |first3=Andrew B. |date=2023 |title=A new aetosaur (Archosauria: Pseudosuchia) from the upper Blue Mesa Member (Adamanian: Early–Mid Norian) of the Late Triassic Chinle Formation, northern Arizona, USA, and a review of the paratypothoracin Tecovasuchus across the southwestern USA |url=https://escholarship.org/uc/item/6q35k21s |journal=PaleoBios |language=en |volume=40 |issue=9 |doi=10.5070/P940961559 |issn=0031-0298|doi-access=free }}</ref>
|2023
|-
|[[Allokotosauria]]
|''[[Puercosuchus traverorum]]''
|Marsh, Parker, Nesbitt, Kligman, & Stocker<ref>{{Cite journal |last1=Marsh |first1=Adam D. |last2=Parker |first2=William G. |last3=Nesbitt |first3=Sterling J. |last4=Kligman |first4=Ben T. |last5=Stocker |first5=Michelle R. |date=July 2022 |title=''Puercosuchus traverorum'' n. gen. n. sp.: a new malerisaurine azendohsaurid (Archosauromorpha: Allokotosauria) from two monodominant bonebeds in the Chinle Formation (Upper Triassic, Norian) of Arizona |journal=Journal of Paleontology |volume=96 |issue=S90 |pages=1–39 |doi=10.1017/jpa.2022.49 |issn=0022-3360|doi-access=free |bibcode=2022JPal...96S...1M }}</ref>
|2022
|-
|[[Cynodont]]ia
|''[[Kataigidodon|Kataigidodon venetus]]''
|Kligman, Marsh, Sues, & Sidor<ref>{{Cite journal |last1=Kligman |first1=Ben T. |last2=Marsh |first2=Adam D. |last3=Sues |first3=Hans-Dieter |last4=Sidor |first4=Christian A. |date=November 2020 |title=A new non-mammalian eucynodont from the Chinle Formation (Triassic: Norian), and implications for the early Mesozoic equatorial cynodont record |journal=Biology Letters |language=en |volume=16 |issue=11 |page=20200631 |doi=10.1098/rsbl.2020.0631 |issn=1744-9561 |pmc=7728676 |pmid=33142088}}</ref>
|2020
|-
|[[Drepanosauromorpha]]
|''[[Skybalonyx|Skybalonyx skapter]]''
|Jenkins, Pritchard, Marsh, Kligman, Sidor & Reed<ref>{{Cite journal |last1=Jenkins |first1=Xavier A. |last2=Pritchard |first2=Adam C. |last3=Marsh |first3=Adam D. |last4=Kligman |first4=Ben T. |last5=Sidor |first5=Christian A. |last6=Reed |first6=Kaye E. |author-link6=Kaye Reed |date=2020-12-01 |title=Using Manual Ungual Morphology to Predict Substrate Use in the Drepanosauromorpha and the Description of a New Species |url=https://www.tandfonline.com/doi/full/10.1080/02724634.2020.1810058 |journal=Journal of Vertebrate Paleontology |language=en |volume=40 |issue=5 |pages=e1810058 |bibcode=2020JVPal..40E0058J |doi=10.1080/02724634.2020.1810058 |issn=0272-4634 |s2cid=225136171}}</ref>
|2020
|-
|[[Allokotosauria]]
|''[[Trilophosaurus|Trilophosaurus phasmalophos]]''
|Kligman, Marsh, Nesbitt, Parker, Stocker<ref name=":4" />
|2020
|-
|[[Drepanosauromorpha]]
|''[[Ancistronychus|Ancistronychus paradoxus]]''
|Gonçalves & Sidor<ref name=":3" />
|2019
|-
|[[Aetosaur]]ia
|''[[Scutarx deltatylus]]''
|Parker<ref>{{Cite journal |last=Parker |first=William G. |date=2016-01-21 |title=Revised phylogenetic analysis of the Aetosauria (Archosauria: Pseudosuchia); assessing the effects of incongruent morphological character sets |journal=PeerJ |language=en |volume=4 |pages=e1583 |doi=10.7717/peerj.1583 |issn=2167-8359 |pmc=4727975 |pmid=26819845 |doi-access=free }}</ref>
|2016
|-
|[[Phytosaur]]ia
|''[[Protome batalaria]]''
|Stocker<ref name=":1" />
|2012
|-
|[[Aetosaur]]ia
|''Adamanasuchus eisenhardtae''
|Lucas, Hunt, & Spielmann<ref>{{Cite journal |last1=Lucas |first1=Spencer G. |last2=Hunt |first2=Adrian P. |last3=Spielmann |first3=Justin A. |date=2007 |title=A new aetosaur from the Upper Triassic (Adamanian: Carnian) of Arizona |url=https://www.researchgate.net/publication/281820635 |journal=New Mexico Museum of Natural History & Science Bulletin |volume=40 |pages=241–247}}</ref>
|2007
|-
|[[Phytosaur]]ia
|''[[Pseudopalatus jablonskiae]]''
|Parker & Irmis<ref>{{Cite journal |last1=Parker |first1=William G. |last2=Irmis |first2=Randall B. |date=2006 |title=A new species of the Late Triassic phytosaur Pseudopalatus (Archosauria: Pseudosuchia) from Petrified Forest National Park, Arizona. |journal=Museum of Northern Arizona Bulletin |volume=62 |pages=126–143}}</ref>
|2006
|-
|[[Allokotosauria]]
|''[[Trilophosaurus|Trilophosaurus dornurum]]''
|Mueller & Parker<ref>{{Cite journal |last1=Mueller |first1=Bill D. |last2=Parker |first2=William G. |date=2006 |title=A new species of Trilophosaurus (Diapsida: Archosauromorpha) from the Sonsela Member (Chinle Formation) of Petrified Forest National Park, Arizona |journal=Museum of Northern Arizona Bulletin |volume=62 |pages=119–125}}</ref>
|2006
|-
|Tetrapoda incertae sedis
|''[[Kraterokheirodon|Kraterokheirodon colberti]]''
|Irmis & Parker<ref>{{Cite journal |last1=Irmis |first1=Randall B |last2=Parker |first2=William G |date=2005-07-01 |title=Unusual tetrapod teeth from the Upper Triassic Chinle Formation, Arizona, USA |url=http://www.nrcresearchpress.com/doi/10.1139/e05-031 |journal=Canadian Journal of Earth Sciences |language=en |volume=42 |issue=7 |pages=1339–1345 |doi=10.1139/e05-031 |bibcode=2005CaJES..42.1339I |issn=0008-4077}}</ref>
|2005
|-
|Reptilia incertae sedis
|''[[Acallosuchus rectori]]''
|Long & Murry<ref name=":0" />
|1995
|-
|[[Dinosaur]]ia
|''[[Chindesaurus bryansmalli]]''
|Long & Murry<ref name=":0" />
|1995
|-
|[[Proterochampsia]]
|''[[Vancleavea campi]]''
|Long & Murry<ref name=":0" />
|1995
|-
|[[Phytosaur]]ia
|''[[Machaeroprosopus mccauleyi|Machaeroprosopus mcauleyi]]''
|Ballew<ref>{{Cite journal |last=Ballew |first=Karen L. |date=1989 |title=A phylogenetic analysis of Phytosauria from the Late Triassic of the western United States |journal=New Mexico Museum of Natural History Bulletin |pages=309–339}}</ref>
|1989
|-
|[[Decapoda]]
|''Enoploclytia porteri''
|Miller & Ash<ref name=":5" />
|1988
|-
|[[Phytosaur]]ia
|''[[Smilosuchus adamanensis]]''
|Camp<ref>{{Cite journal |last=Camp |first=Charles L. |date=1930 |title=A study of the phytosaurs: with description of new material from western North America |journal=Memoirs of the University of California |volume=10 |pages=1–161}}</ref>
|1930
|-
|[[Phytosaur]]ia
|''[[Machaeroprosopus pristinus]]''
|Mehl<ref>{{Cite journal |last=Mehl |first=Maurice G. |date=1928 |title=Pseudopalatus pristinus a new genus and species of phytosaurs from Arizona |journal=University of Missouri Quarterly |volume=3 |pages=1–25}}</ref>
|1928
|}

==Climate==
According to the [[Köppen climate classification]] system, Petrified Forest National Park has a [[cold semi-arid climate]] (''BSk''). According to the [[United States Department of Agriculture]], the plant [[hardiness zone]] at the Painted Desert Visitor Center {{convert|5764|ft}} is 7a with an average annual extreme minimum temperature of {{convert|3.1|F}}.<ref name="USDA">{{cite web|url=https://planthardiness.ars.usda.gov/PHZMWeb/InteractiveMap.aspx|publisher=[[United States Department of Agriculture]]|access-date=July 16, 2019|title=USDA Interactive Plant Hardiness Map}}</ref>

Winter winds can reach {{convert|60|mph|km/h}}.<ref name="NPS weather" /> Summer breezes are lighter, but the {{convert|10|mph|km/h|adj=on}} average wind causes frequent sandstorms and [[dust devil]]s, some of which reach altitudes of several thousand feet.<ref name="NPS weather" />

Rain is heaviest from July through September, when 42&nbsp;percent of the park's annual average precipitation falls. August is the wettest month. At an elevation of more than {{convert|5000|ft|m}},<ref name="gnis" /> Petrified Forest National Park has a chance of light snow from October through March, although snow cover rarely persists.{{sfn|Ash|p=44}} The annual average [[relative humidity]] of the area is below 50&nbsp;percent and at times less than 15&nbsp;percent.<ref name="NPS weather" />

{{Weather box
|location = Petrified Forest National Park, Arizona, 1991–2020 normals, extremes 1931–present
|single line = Yes

|Jan record high F = 74
|Feb record high F = 77
|Mar record high F = 88
|Apr record high F = 92
|May record high F = 99
|Jun record high F = 107
|Jul record high F = 105
|Aug record high F = 103
|Sep record high F = 99
|Oct record high F = 92
|Nov record high F = 83
|Dec record high F = 72

|Jan avg record high F = 62.3
|Feb avg record high F = 68.6
|Mar avg record high F = 76.3
|Apr avg record high F = 83.4
|May avg record high F = 91.6
|Jun avg record high F = 99.8
|Jul avg record high F = 100.8
|Aug avg record high F = 97.5
|Sep avg record high F = 92.9
|Oct avg record high F = 85.6
|Nov avg record high F = 74.3
|Dec avg record high F = 64.1
|year avg record high F = 101.9

|Jan high F = 50.0
|Feb high F = 56.4
|Mar high F = 64.5
|Apr high F = 72.1
|May high F = 80.8
|Jun high F = 91.4
|Jul high F = 93.3
|Aug high F = 90.5
|Sep high F = 84.9
|Oct high F = 73.9
|Nov high F = 60.9
|Dec high F = 49.6
|year high F =

|Jan mean F = 35.6
|Feb mean F = 40.3
|Mar mean F = 47.1
|Apr mean F = 53.8
|May mean F = 62.2
|Jun mean F = 72.1
|Jul mean F = 76.7
|Aug mean F = 74.9
|Sep mean F = 68.4
|Oct mean F = 56.6
|Nov mean F = 44.5
|Dec mean F = 35.1
|year mean F =

|Jan low F = 21.1
|Feb low F = 24.3
|Mar low F = 29.7
|Apr low F = 35.5
|May low F = 43.5
|Jun low F = 52.7
|Jul low F = 60.1
|Aug low F = 59.3
|Sep low F = 51.9
|Oct low F = 39.3
|Nov low F = 28.1
|Dec low F = 20.7
|year low F =

|Jan avg record low F = 5.8
|Feb avg record low F = 10.6
|Mar avg record low F = 15.6
|Apr avg record low F = 23.5
|May avg record low F = 31.5
|Jun avg record low F = 41.8
|Jul avg record low F = 51.5
|Aug avg record low F = 52.1
|Sep avg record low F = 39.3
|Oct avg record low F = 24.8
|Nov avg record low F = 13.8
|Dec avg record low F = 5.7
|year avg record low F = 1.6

|Jan record low F = -27
|Feb record low F = -8
|Mar record low F = 2
|Apr record low F = 12
|May record low F = 19
|Jun record low F = 31
|Jul record low F = 42
|Aug record low F = 41
|Sep record low F = 29
|Oct record low F = 8
|Nov record low F = -13
|Dec record low F = -18

|precipitation colour = green
|Jan precipitation inch = 0.59
|Feb precipitation inch = 0.64
|Mar precipitation inch = 0.65
|Apr precipitation inch = 0.40
|May precipitation inch = 0.43
|Jun precipitation inch = 0.24
|Jul precipitation inch = 1.72
|Aug precipitation inch = 1.58
|Sep precipitation inch = 1.02
|Oct precipitation inch = 0.89
|Nov precipitation inch = 0.67
|Dec precipitation inch = 0.78
|year precipitation inch =

|unit precipitation days = 0.01 in
|Jan precipitation days = 5.7
|Feb precipitation days = 4.8
|Mar precipitation days = 4.7
|Apr precipitation days = 3.3
|May precipitation days = 3.7
|Jun precipitation days = 2.2
|Jul precipitation days = 8.8
|Aug precipitation days = 9.4
|Sep precipitation days = 5.2
|Oct precipitation days = 4.9
|Nov precipitation days = 3.9
|Dec precipitation days = 5.3

|Jan snow inch = 0.8
|Feb snow inch = 0.6
|Mar snow inch = 0.8
|Apr snow inch = 0.0
|May snow inch = 0.0
|Jun snow inch = 0.0
|Jul snow inch = 0.0
|Aug snow inch = 0.0
|Sep snow inch = 0.0
|Oct snow inch = 0.2
|Nov snow inch = 0.3
|Dec snow inch = 0.8
|year snow inch =

|unit snow days = 0.1 in
|Jan snow days = 0.5
|Feb snow days = 0.4
|Mar snow days = 0.3
|Apr snow days = 0.0
|May snow days = 0.0
|Jun snow days = 0.0
|Jul snow days = 0.0
|Aug snow days = 0.0
|Sep snow days = 0.0
|Oct snow days = 0.1
|Nov snow days = 0.1
|Dec snow days = 0.7

|source 1 = NOAA<ref name = NOAA>
{{cite web
|url = https://www.ncei.noaa.gov/access/services/data/v1?dataset=normals-monthly-1991-2020&stations=USC00026468&format=pdf&dataTypes=MLY-TMAX-NORMAL,MLY-TMIN-NORMAL,MLY-TAVG-NORMAL,MLY-PRCP-NORMAL,MLY-SNOW-NORMAL
|publisher = National Oceanic and Atmospheric Administration
|title = U.S. Climate Normals Quick Access – Station: Petrified Forest NP, AZ
|access-date = March 25, 2023
}}
</ref>
|source 2 = National Weather Service<ref name = NOWData>
{{cite web
|url = https://www.weather.gov/wrh/climate?wfo=fgz
|publisher = National Weather Service
|title = NOAA Online Weather Data – NWS Flagstaff
|access-date = March 25, 2023
}}
</ref>
}}

== History ==

===Pre-United States===
{{multiple image
 | direction = horizontal
 | total_width = 360
 | image1 = Puerco Pueblo ruins.jpg
 | alt1 = Ruins at Puerco Pueblo consisting of very low walls, about a meter (three feet) tall, of stacked reddish-brown rocks forming the rectangular shapes of a multi-room structure, surrounded by short greenish, yellow desert vegetation slightly taller than the walls
 | caption1 = Ruins at Puerco Pueblo in 2010
 | image2 = Annual report of the Board of Regents of the Smithsonian Institution (1901) (17813445324).jpg
 | alt2 = Two bowls about 8.75 inches in diameter and about 3.75 inches tall, one is yellowish-brown with intricate dark patterns, while the other is reddish-brown with light-colored lines, found at the Stone Axe Ruin in Arizona
 | caption2 = Bowls, Stone Axe Ruin
}}

More than 1200 archeological sites have been found inside the boundaries of Petrified Forest National Park. Evidence suggests that the earliest inhabitants of the park arrived over 12,000 years ago. Clovis and [[Folsom point|Folsom-type]] spear points made from petrified wood are among the earliest artifacts of [[Paleoindians]] found in the park. Between {{BCE|8,000 and 1,000|link=y}}, the [[Archaic stage|Archaic Period]], nomadic groups established seasonal camps in the Petrified Forest from which they hunted game such as rabbits, [[pronghorn]] antelope, and deer and harvested seeds from [[Achnatherum hymenoides|Indian ricegrass]] and other wild plants. By at least {{BCE|1000}} and through the [[Early Basketmaker II Era|Basketmaker II]] period ({{BCE|400}}–{{CE|500|link=y}})Ancestral Puebloan farmers began to grow corn. Between {{CE|200–500}} population size grew rapidly. Many families built houses in the Petrified Forest and for the first time began to stay there year-round.{{sfn|Jones|pp=9–11}}

During the [[Basketmaker III Era|Basketmaker III]] period, {{CE|500–700}}, families occupied shallow subterranean pit structures, at first on [[mesa]]s or other vantage points and later at the base of [[Cliff|bluffs]] and in lowlands, where the soil was better. Settlement patterns shifted and population size grew during the Pueblo I era between 700 and 900&nbsp;CE and for the first time large groups of families aggregated together and formed large villages. During this period, each household built large well-insulated subterranean residential pit structures to keep warm during the cold winter months and several adjacent above ground rooms made from stone and jacal similar to adobe—used for food storage and daily activities during the warmer months. During the early Pueblo II period ({{CE|900–1050}}) Ancestral Pueblo farmers began constructing above-ground masonry architecture (for example Agate House, a small masonry structure built from petrified wood that is open to the public) signaling a greater degree of residential permanence. During the Late Pueblo II and Early Pueblo III periods 1050–1225 local population size grew rapidly. Similar to much of the Ancestral Pueblo world, population density increased rapidly at this time and nearly 1,000 sites dating to this period have been identified in the park at a wide variety of locations—at the mouths of [[Arroyo (watercourse)|washes]], near [[seep (hydrology)|seeps]], and on moisture-holding sand dunes.{{sfn|Jones|pp=11–13}}

[[File:Lith side wash petroglyphs 1.jpg|thumb|left|alt=Images of animals, people, and geometric figures incised on the dark vertical face of a large rock|Petroglyphs pecked into desert varnish in Petrified Forest National Park]]

Between 1250 and 1450 CE Ancestral Pueblo families gathered into large apartment building-like masonry structures (also known as pueblos) with several hundred people living together in close quarters These large villages were often located near important water sources.{{sfn|Jones|p=15}} Ancestral Pueblo people constructed more than two of these large pueblos, one called Stone Axe, about {{convert|0.5|mi|km|1}} east of the park, and the other at Puerco Pueblo, which overlooks the Puerco River near the middle of the park.{{sfn|Jones|p=18}} There they built roughly 200 rooms around an open plaza.{{sfn|Jones|p=18}} Some rooms had no windows or doors and could be entered by climbing a ladder and descending through a hole in the roof. At its peak, perhaps 200 people lived in this pueblo.{{sfn|Jones|p=18}} Over time, however, Ancestral Pueblo families undertook migrations and joined rapidly growing towns on the Hopi Mesas in Northern Arizona and at the Pueblo of Zuni in northern New Mexico, where the descendants of the ancient Petrified Forest farmers still live today. Some researchers have argued that a persistently dry climate led to out-migration, and the last residents left Puerco Pueblo in about 1380&nbsp;CE.{{sfn|Jones|p=21}}

At Puerco Pueblo and many other sites within the park, [[petroglyph]]s—images, symbols, or designs—have been scratched, pecked, carved, or incised on rock surfaces, often on a patina known as [[desert varnish]]. Most of the petroglyphs in Petrified Forest National Park are thought to be between 650 and 2,000 years old.<ref>{{cite web | title = Messages on Stone | publisher = National Park Service | url = http://www.nps.gov/pefo/upload/MessagesOnStone2006.pdf| access-date = October 15, 2010 | archive-url = https://web.archive.org/web/20121107084153/http://www.nps.gov/pefo/upload/MessagesOnStone2006.pdf | archive-date = November 7, 2012 | url-status = live}}</ref>

From the 16th through the 18th&nbsp;centuries, explorers looking for routes between Spanish colonies along the [[Rio Grande]] to the southeast and other Spanish colonies on the Pacific coast to the west passed near or through the area, which they called ''El Desierto Pintado'', the Painted Desert. However, the park's oldest Spanish inscriptions, left by descendants of the region's early Spanish colonists, date only to the late 19th&nbsp;century.<ref name="NPS history" />

===United States===
[[File:Lithodendron wash PEFO.jpg|thumb|alt=A sandy stream bed. In places, the sand is darkened by moisture.|Lithodendron Wash in the designated wilderness in the north part of the park. Amiel Whipple surveyed along the wash in 1853.]]

After the [[Southwestern United States|Southwest]] became [[Mexican Cession|part of the U.S.]], explorers continued to look for good east–west routes along the [[35th parallel north|35th&nbsp;parallel]]. In 1853, a crew led by [[U.S. Army]] [[Lieutenant]] [[Amiel Weeks Whipple|Amiel Whipple]] surveyed along a sandy wash in the northern part of the Petrified Forest. So impressed was Whipple by the petrified wood along the banks of the [[Arroyo (watercourse)|arroyo]] that he named it Lithodendron Creek (Stone Tree Creek). Geologist [[Jules Marcou]], a member of the Whipple expedition, observed that the petrified trees were from the Triassic.<ref name="NPS history" />

A slightly later route along the parallel was a wagon road, built between 1857 and 1860, that involved experimental use of camels as transport. In the late 19th&nbsp;century, settlers and private [[stagecoach]] companies followed similar east–west routes. [[Homestead Act|Homesteaders]] who stayed in the area developed cattle ranches on the grasslands, and cattle grazed in the Petrified Forest until the mid-20th&nbsp;century.<ref name="NPS history" />

Also close to the 35th&nbsp;parallel was the [[Atlantic and Pacific Railroad]]. Its opening in the early 1880s led to the founding of towns like Holbrook and Adamana. Visitors could stop at the Adamana train station, book a hotel room, and take a tour of what was then called the [[Chalcedony]] Forest. Over the years, the line changed hands, becoming the [[Atchison, Topeka and Santa Fe Railway]], and then the BNSF. More than 60 BNSF trains, mostly carrying freight, pass through the park every day. U.S. Route&nbsp;66, a former transcontinental auto highway developed in 1926 from part of the [[National Old Trails Road]], ran parallel to the railroad tracks until it was decommissioned in 1985. The park has preserved within its boundaries a small grassy section of the road. [[Interstate 40 in Arizona|Interstate&nbsp;40]], which crosses the park, replaced the older highway.<ref name="NPS history" />

[[File:Route 66 car petrified forest.jpg|thumb|left|alt=The hulk of an old car mounted on supports above a bed of gravel|Exhibit commemorating [[U.S. Route 66]], a historic transcontinental highway that passed through the park]]

Increasing tourist and commercial interest in petrified wood during the late 19th&nbsp;century began to alarm residents of the region. In 1895, the [[Arizona Territorial Legislature]] asked the [[United States Congress|U.S. Congress]] to create a petrified forest national park. Although this first attempt failed, in 1906 the [[Antiquities Act]] signed by President [[Theodore Roosevelt]] was used to create the Petrified Forest National Monument as the second [[National monument (United States)|national monument]]. Between 1934 and 1942, the federal [[Civilian Conservation Corps]] built road, trails, and structures in the monument, and the government acquired additional land in the Painted Desert section. The monument became a national park in 1962. Six years after the signing of the [[Wilderness Act]] in 1964 by President [[Lyndon B. Johnson]], [[National Wilderness Preservation System|wilderness areas]] (where human activity is limited), were designated in the park. In 2004, President [[George W. Bush]] signed a bill authorizing the eventual expansion of the park from 93,353&nbsp;acres (about 146&nbsp;mi<sup>2</sup> or 378&nbsp;km<sup>2</sup>) to 218,533&nbsp;acres (about 341&nbsp;mi<sup>2</sup> or 884&nbsp;km<sup>2</sup>).<ref name="NPS history" /> Theft of petrified wood is still a problem. Despite a guard force of seven [[National Park Service]] [[Park ranger|rangers]], fences, warning signs, and the threat of a $325&nbsp;[[Fine (penalty)|fine]], an estimated {{convert|12|ST|kg|lk=on}} of the fossil wood is stolen from the Petrified Forest every year.<ref>{{cite web| url = https://query.nytimes.com/gst/fullpage.html?res=9E07E1DD123FF93BA15752C1A96F958260&partner=rssnyt&emc=rss | title = Petrified Forest Shrinks, One Stolen Piece at a Time|work = The New York Times|date= November 28, 1999 | access-date = November 6, 2008}}</ref>

[[J. Walter Fewkes|Jessee Walter Fewkes]], the first [[Archeology|archeologist]] to visit Puerco Ruin, predicted in the late 19th&nbsp;century that it would yield many artifacts.{{sfn|Jones|pp=37–39}} Conservationist [[John Muir]] conducted the first excavations of the ruin in 1905–06. Although he did not publish his findings, he urged the federal government to preserve Petrified Forest.{{sfn|Jones|pp=37–39}} Professional archeological work in the park began in the early 20th&nbsp;century when [[Walter Hough]] conducted excavations at Puerco Ruin and other sites.<ref name="NPS history" /> In the 1930s, the [[Civil Works Administration]] funded research in the park by archeologists H.P. Mera and C.B. Cosgrove.<ref name="NPS history" /> A National Park Service resurvey of the Petrified Forest in the early 1940s identified most of the large sites with stone ruins, and subsequent surveys since 1978 have identified a total of more than 600 artifact sites, many of them small.{{sfn|Jones|pp=37–39}}

The earliest paleontological exploration of the region that is now the park was made in 1899 by paleobotanist [[Lester Frank Ward|Lester Ward]], material of which is now deposited in the [[Smithsonian Institution]]. Muir also collected some fossil material, which is now deposited at the [[University of California Museum of Paleontology]]. In 1919, a phytosaur skull was discovered near Blue Mesa in the Petrified Forest by Ynez Mexia and sent to the Museum of Paleontology in Berkeley.<ref name=":0" /><ref name="NPS history" /> In 1921, [[Annie Montague Alexander|Annie Alexander]], founder of the museum, visited Blue Mesa to collect more of the phytosaur and other specimens; this led to further excavations by paleontologist [[Charles Lewis Camp|Charles Camp]].<ref name="NPS history" /> Camp was the most prolific collector in the early 20th century, but collections were also made by [[Maurice Mehl]] (University of Missouri), [[Edwin H. Colbert|Edwin Colbert]] (American Museum of Natural History), and park naturalists like Myrl Walker. In the latter half of the 20th century, the park was inventoried by staff at the [[Museum of Northern Arizona]] (Richard Cifelli, Will Downs), with renewed collection made by researchers from Berkeley (Robert Long, Kevin Padian), the University of Chicago (Michael Parrish), the Field Museum of Natural History (John Bolt), and Yale University (Paul Olsen). Since then, more than 300 fossil sites have been documented in the park.<ref name=":6" /> Research in paleontology and archeology continues at the park in the 21st&nbsp;century.<ref name="NPS history" />

== Biology ==
            
=== Flora ===
[[File:Tiponi Point at sunset.jpg|thumb|right|alt=View from a highly vegetated overlook toward a relatively barren badlands of rounded buttes and small arroyos|At Tiponi Point, lush vegetation on the Painted Desert rim overlooks the relatively barren badlands below.]]

According to the [[A. W. Kuchler]] U.S. [[Potential natural vegetation]] Types, Petrified Forest National Park encompasses two classifications; a Grama [[Bouteloua]]/Galleta [[Hilaria (plant)]] [[Steppe]] (''53'') potential vegetation type with a [[Desert]] [[Grassland]] (''12'') vegetation form and a [[Juniper]]/[[Pinyon pine]] (23) vegetation type with a [[Great Basin montane forest]]/Southwest Forest (4) vegetation form.<ref name="Conservation Biology Institute">{{cite web|url=https://databasin.org/datasets/1c7a301c8e6843f2b4fe63fdb3a9fe39|publisher=[[Data Basin]]|access-date=July 16, 2019|title=U.S. Potential Natural Vegetation, Original Kuchler Types, v2.0 (Spatially Adjusted to Correct Geometric Distortions)}}</ref>

A 2005 survey found that 447 species of flora, of which 57 species are [[invasive species|invasive]], occur in the park.{{sfn|Hansen & Thomas|pp=27, 29}} Although the park is known for its fossils and eroded badlands, its main environment is semi-desert shrub steppe. Protected from development and [[overgrazing]] for many years, the park has some of the best grassland in northeastern Arizona.<ref name="NPS grassland" /> In the northern part of the park, the volcanic soils of the Bidahochi Formation support abundant plant life along the Painted Desert rim.<ref name="NPS grassland" /> In contrast to the relatively bare badlands below, the rim is covered with shrubs, small trees, grasses, and herbs.<ref name="NPS grassland" />

The dominant plants in the park include more than 100 grass species, many native to the region. Growing among the grasses are flowering species such as [[Oenothera|evening primrose]], [[Calochortus|mariposa lily]], and [[Linum lewisii|blue flax]], and shrubs such as [[Artemisia tridentata|sagebrush]], [[Atriplex|saltbush]], and [[Chrysothamnus|rabbitbrush]]. Among the wide variety of grasses are native perennial [[Tussock (grass)|bunchgrass]], [[blue grama]], [[Sporobolus|sacaton]], [[Bouteloua curtipendula|sideoats grama]], [[Leptochloa|bearded sprangletop]], and [[Muhlenbergia porteri|bush muhly]]. Invasive species that crowd out slower-spreading natives include annual [[Eragrostis|lovegrass]] and [[Bromus|brome]] (cheat grass).<ref name="NPS grassland" />

Trees and shrubs grow in [[riparian zone]]s along the park's washes. Willows and cottonwoods are the larger plants, joined by rushes and sedges. Here the invasive Eurasian [[tamarisk]], also known as saltcedar, threatens native plants by crowding, using most of the available water, and increasing [[soil salinity]] by exuding salt through its leaves.<ref name="NPS grassland" />

=== Fauna ===
[[File:Coyote arizona.jpg|thumb|upright|alt=A brown, four-footed, dog-like animal stares at the camera| Coyotes are [[omnivore]]s with a widely varied diet including many rodents.]]

Some of the larger animals roaming the grasslands include [[pronghorn]]s, [[black-tailed jackrabbit]]s (hares), [[Gunnison's prairie dog]]s, [[Mearns coyote|coyote]]s, [[bobcat]]s and foxes. Pronghorns, the fastest land animals in North America, are capable of {{convert|60|mph|km/h|adj=on}} sprints.<ref name="NPS grassland" /> They are the second fastest land animal on Earth. The blood vessels in the huge, thin-walled ears of the jackrabbits act as heat exchangers. These hares are known for their bursts of speed, long leaps, and zigzag routes, all of which protect them from being eaten by [[golden eagles]] and other predators.<ref name="NPS mammals" /> The prairie dogs live in large colonies or "towns", near which many other species find food and shelter.<ref name="NPS grassland" /> Coyotes dine largely on rodents but also eat fruits, reptiles, insects, small mammals, birds, and [[carrion]].<ref name="NPS mammals" />

Bobcats and [[bullsnake]]s hunt smaller animals, such as [[Peromyscus|deer mice]] and [[white-tailed antelope squirrel]]s in the park's riparian zones. [[Western Pipistrelle|Western pipistrelle]] bats feast on insects,<ref name="NPS grassland" /> and [[pallid bat]]s eat beetles, [[centipede]]s, [[cicada]]s, praying [[mantis]]es, [[scorpion]]s, and other [[arthropod]]s.<ref name="NPS mammals" /> On the Painted Desert rim, small animals find food and shelter among the denser foliage, and [[mule deer]] sometimes frequent the area.<ref name="NPS grassland" />

More than 16 kinds of lizards and snakes live in various habitats in the park and consume large quantities of insects, spiders, scorpions, other reptiles, and small mammals. The [[Crotaphytidae|collared lizard]], which occurs in every habitat, is the largest and most often seen.[[File:Crotaphytus collaris -Petrified Forest National Park, Arizona, USA-8.jpg|thumb|left|alt=A green lizard with yellow feet rests on a bed of sand and gravel.|The collared lizard is the largest lizard in the park.]] Plateau striped [[Teiidae|whiptails]], a species consisting entirely of females, prefer grasslands and developed areas. [[Side-blotched lizard]]s live in rocky areas of the park but are seldom seen. [[Gopher snake]]s, which sometimes imitate rattlesnakes when disturbed, are among the most common snakes in the park. The [[Crotalus viridis|Prairie rattlesnake]], the only venomous snake found in the park, prefers grasslands and shrub areas.<ref name="NPS modern reptiles" />

Seven kinds of [[amphibian]]s, which drink no water but absorb it through their permeable skins, have been identified in Petrified Forest National Park. [[Tiger salamanders]], found in grassland and near major drainages, are the only salamander species known in Arizona. [[Woodhouse's toad]]s, which are seldom seen, are the largest toads in the park. They like grasslands, riparian corridors, and developed areas. [[Red-spotted toad]]s, most active in the rainy season, July through September, are found in rocky areas near streams and in canyons. The [[Great Plains toad]], the most common toad in the park, prefers grasslands. Resident [[American spadefoot toads|spadefoot toads]] include the New Mexico, plains, and Couch's varieties.<ref name="NPS amphibians" />

[[File:Western Meadowlark.jpg|thumb|upright|alt=A bird with a bright yellow breast is perched on the ground amid grasses.|Western meadowlarks, prized for their song, frequent the park.]]

A survey conducted in 2006 identified 216 species of birds known to have occurred in Petrified Forest National Park since the park became a protected area in 1906. Of those, 33 species breed within the park, 6 other species probably do, and 18 species live in the park year-round. Thirty-five species live in the park only during the summer and 11 species only during the winter. The greatest diversity of birds occurs during fall and winter migrations.{{sfn|Van Riper & Lamow|p=18}}

[[Bird of prey|Raptors]], songbirds, and ground birds are found in the park's grassland, while the Puerco River's riparian corridor is a good place for year-round residents as well as migrants such as [[warbler]]s, [[vireo]]s, [[American avocet|avocets]], and [[killdeer]]. Developed areas around the visitor center and museum attract [[western tanager]]s, [[hermit warbler]]s, [[house finch]]es, and others. Occasional shorebirds and eastern birds also visit the park.<ref name="NPS birds" />

Birds commonly seen in the park include the [[common raven]] and the [[western meadowlark]], known for its charming song. [[Anna's hummingbird]], which can hover and fly backwards as well as forwards, is among the smallest birds in the park. The largest is the [[golden eagle]], with a wingspan of up to {{convert|7|ft|m|0}}.<ref name="NPS birds" />

== Activities ==
[[File:PEFO park map 2006 large.png|thumb|500px|alt=Interstate 40 and U.S. Route 180 connect to the main park road, which runs between the park's north and south entrances and provides access to its main viewing points, trails, and public buildings.|Map of the park]]
[[File:Petrified log, Petrified Forest National Park, Arizona.png|thumb|Closeup of a specimen of petrified wood.]]
The park is open every day except Christmas on a schedule that varies slightly with the seasons. In 2010, it and its Painted Desert Visitor Center and Rainbow Forest Museum were open from 7&nbsp;a.m. to 7&nbsp;p.m. from May&nbsp;9 through September&nbsp;6 but opened as early as 8&nbsp;a.m. and closed as late as 5&nbsp;p.m. during other parts of the year. The [[Painted Desert Inn]] (a historic museum and bookstore) is open from 9&nbsp;a.m. to 5&nbsp;p.m. year-round except Christmas. Park clocks are always set to [[Mountain Time Zone|Mountain Standard Time]], as Arizona does not observe [[Daylight Saving Time]].<ref>{{cite web | title = Operating Hours & Seasons | publisher = National Park Service | url = http://www.nps.gov/pefo/planyourvisit/hours.htm|year = 2010 | access-date = October 15, 2010}}</ref>

The Painted Desert Visitor Center, designed by modernist architect [[Richard Neutra]], is part of the [[Painted Desert Community Complex Historic District]] listed on the [[National Register of Historic Places]].<ref>{{cite web | title = Science and Education Center Lecture Series, April 2008 | publisher = National Park Service | url = http://www.nps.gov/pefo/parknews/lecture-april-2008.htm |year = 2008 | access-date = October 15, 2010 | archive-url = https://web.archive.org/web/20151007172943/http://www.nps.gov/pefo/learn/news/lecture-april-2008.htm | archive-date = October 7, 2015 | url-status = live}}</ref> Eight other sites within the park are also on the National Register, including the Painted Desert Inn and associated cabins, the [[Agate House Pueblo]], the Painted Desert Petroglyphs and Ruins Archeological District, [[Newspaper Rock Petroglyphs Archeological District]], [[Puerco Ruin and Petroglyphs]], the [[Flattop Site]] (an archeological site), the [[Twin Buttes Archeological District]], and the 35th Parallel Route (also known as the Beale Camel Trail). The Painted Desert Inn was upgraded to a [[National Historic Landmark]] in 1987.<ref>{{cite web | title = The National Register of Historic Places | publisher = National Park Service | url = http://www.nps.gov/pefo/historyculture/the-national-register-of-historic-places.htm| year = 2007 | access-date = October 15, 2010 | archive-url = https://web.archive.org/web/20121107084118/http://www.nps.gov/pefo/historyculture/the-national-register-of-historic-places.htm |archive-date = November 7, 2012 }}</ref>

The visitor center, which is near the north entrance to the park, offers visitor information and shows a 20-minute orientation movie, "Timeless Impressions", once every half-hour. It has a bookstore, exhibits, a restaurant open from 8&nbsp;a.m. to 3&nbsp;p.m., a gift shop, a gas station, a post office open from 11&nbsp;a.m. to 1&nbsp;p.m. Monday through Friday, a postal drop box, and public restrooms. The Rainbow Forest Museum complex {{convert|2|mi|km}} north of the park's south entrance offers services including information and "Timeless Impressions" showings once every half-hour. It has a bookstore, fossil exhibits, an interactive Triassic Virtual Tour, limited food service, a gift shop, and public restrooms. The Painted Desert Inn, {{convert|2|mi|km}} north of the Painted Desert Visitor Center, offers visitor information. It has a bookstore, museum exhibits (including the building itself), and public restrooms.<ref name="Things to Know" />

No campgrounds or overnight lodging are available in the park, although nearby communities such as Holbrook offer motels and other accommodations.<ref name="Things to Know" /> Overnight parking is not allowed<ref name="Things to Know" /> except in the case of [[Backpacking (wilderness)|backpackers]] with wilderness hiking permits.<ref name="Backpacking" /> Sightseeing is available by private automobile, motorcycle, commercial tour, bicycle, and hiking. The park road, parking lots, and turn-outs are big enough to accommodate large recreational vehicles. Off-road vehicle travel, including by [[mountain bike]], is not allowed.<ref>{{cite web | title = Plan Your Visit | publisher = National Park Service | url = http://www.nps.gov/pefo/planyourvisit/ |year = 2010 | access-date = October 9, 2010 | archive-url = https://web.archive.org/web/20110225211258/http://www.nps.gov/pefo/planyourvisit/index.htm | archive-date = February 25, 2011 }}</ref> With a few exceptions such as unpaved Old Highway 66, bicycles must stay on paved roads such as the {{convert|28|mi|km|adj=on}} main park road and stay off trails and unpaved surfaces.<ref>{{cite web | title = Getting Around | publisher = National Park Service | url = http://www.nps.gov/pefo/planyourvisit/gettingaround.htm | year = 2015 | access-date = October 7, 2015 | archive-url = https://web.archive.org/web/20150715110414/http://www.nps.gov/pefo/planyourvisit/gettingaround.htm | archive-date= July 15, 2015 | url-status = live}}</ref>

The park's seven maintained hiking trails, some paved, vary in length from less than {{convert|0.5|mi|km|1}} to nearly {{convert|3|mi|km}}. Pets are allowed on these trails if kept on a leash, but bicycles are not. These named trails are Painted Desert Rim, Puerco Pueblo, Blue Mesa, Crystal Forest, Giant Logs, Long Logs, and Agate House.<ref name="Trails" /> There are also nine recently developed day-hike routes on unpaved and largely unmarked routes called "Off the Beaten Path" hikes.<ref>{{Cite web |title=Off the Beaten Path - Petrified Forest National Park (U.S. National Park Service) |url=https://www.nps.gov/pefo/off-the-beaten-path.htm |access-date=2022-03-13 |website=www.nps.gov |language=en}}</ref> Hikers and backpackers may also visit the park's wilderness areas. Free permits are required for overnight stays; they are issued from the Painted Desert Visitor Center, Painted Desert Inn, and Rainbow Forest Museum. Most backpackers enter the wilderness at the north end of the park, where parking and an access trail are available at Painted Desert Inn. Group camping is limited to eight people.<ref name="Backpacking" /> Horseback riding is allowed in the wilderness areas; water for horses is available at the service station near the Painted Desert Visitor Center. Riders and hikers are asked to travel along dry washes as much as possible to reduce the impact on fragile desert soils.<ref>{{cite web | title = Horseback Riding | publisher = National Park Service| url = http://www.nps.gov/pefo/planyourvisit/horseback-riding.htm|year = 2009 | access-date = October 9, 2010 | archive-url = https://web.archive.org/web/20150303073428/http://www.nps.gov/pefo/planyourvisit/horseback-riding.htm | archive-date = March 3, 2015 | url-status = live}}</ref>

Rangers offer a variety of programs about the park. Regularly scheduled events include a Painted Desert Inn tour, a Triassic program at the Rainbow Forest Museum sunroom, a talk or walk along the Giant Logs Trail behind the museum, and a Puerco Pueblo guided walk.<ref>{{cite web | title = Programs, Activities, and Events | publisher = National Park Service | year = 2010| url = http://www.nps.gov/pefo/planyourvisit/guidedtours.htm | access-date = October 9, 2010}}</ref> The park hosts special events related to [[Earth Science Week]] and [[National American Indian Heritage Month]].<ref>{{cite web | title = Calendar of Events | publisher = National Park Service | url = http://www.nps.gov/pefo/planyourvisit/calendar-of-events.htm | year = 2010 | access-date = October 9, 2010 | archive-url = https://web.archive.org/web/20101007085531/http://www.nps.gov/pefo/planyourvisit/calendar-of-events.htm <!--Added by H3llBot--> | archive-date = October 7, 2010 }}</ref> On Saturdays from [[Memorial Day]] weekend through [[Labor Day]] at the Painted Desert Inn, artisans from the region give cultural demonstrations related to ancient peoples, intertribal relationships, and European-descent cultures.<ref>{{cite web | title = Cultural Demonstrations | publisher = National Park Service | url = http://www.nps.gov/pefo/planyourvisit/cultural-demonstrations.htm |year = 2010 | access-date = October 15, 2010 | archive-url = https://web.archive.org/web/20130617234535/http://www.nps.gov/pefo/planyourvisit/cultural-demonstrations.htm | archive-date = June 17, 2013 | url-status = live}}</ref> For students and teachers, the rangers offer educational materials and field-trip talks.<ref>{{cite web | title = Education| publisher = National Park Service| url = http://www.nps.gov/pefo/forteachers/ |year = 2010 | access-date = November 1, 2010 | archive-url = https://web.archive.org/web/20150906181542/http://www.nps.gov/pefo/learn/education/index.htm | archive-date = September 6, 2015| url-status = live}}</ref> In some years during the summer months, artists-in-residence work in the park.<ref>{{cite web | title = 2014 Artist-In-Residence | publisher = National Park Service | url = http://www.nps.gov/pefo/learn/news/2014-artist-in-residence.htm |year = 2014 | access-date = October 7, 2015 }}</ref>

{{clear}}
{{wide image|Shortgrass pano Petrified Forest NP.jpg|1000px|alt=Panorama of prairie covered with short brown and yellow grasses. Hills rise in the distance, and a large cloud shadow darkens a small part of the prairie. |Panorama of [[shortgrass prairie]] near Dry Wash in the southern section of the park. View is to the east from near the main park road. The dark area on the ground to the right is a cloud shadow.}}

== See also ==
* [[Ancestral Puebloans]]
* [[Cuarenta Casas|Forty Houses, Chihuahua]]
* [[Gila Cliff Dwellings National Monument]]
* [[Hohokam]]
* [[Hubbell Trading Post National Historic Site]]
* [[Kinishba Ruins]]
* [[List of national parks of the United States]]
* [[List of areas in the United States National Park System]]
* [[Mogollon culture]]
* [[Casas Grandes|Paquimé, Chihuahua]]
* [[Southwestern archaeology]]

== References ==
{{reflist
| colwidth = 30em
| refs =
<ref name="gnis">
{{cite web | work = [[Geographic Names Information System]] (GNIS) | publisher = United States Geological Survey | date = June 27, 1984 | url = http://geonames.usgs.gov/pls/gnispublic/f?p=gnispq:3:::NO::P3_FID:23864 | title = Petrified Forest National Park | access-date = October 1, 2010
}}
</ref>

<ref name="red book">
{{cite book | title = The National Parks Index 2009–2011 | publisher= National Park Service | year = 2009 | url = http://www.nps.gov/history/history/online_books/nps/index2009_11.pdf | isbn = 978-0-912627-81-6 | access-date = October 7, 2010 | archive-url = https://web.archive.org/web/20111016070121/http://www.nps.gov/history/history/online_books/nps/index2009_11.pdf |archive-date = October 16, 2011
}}
</ref>

<ref name="DeLorme Arizona">
{{cite map | publisher = DeLorme Mapping | title = Arizona Atlas and Gazetteer | edition = 2008 | section = 38–39 | isbn = 978-0-89933-325-0
}}
</ref>

<ref name="Rand McNally">
{{cite map | publisher = Rand McNally & Company | title = The Road Atlas | edition = 2008 | section = 8–9 | isbn = 978-0-528-93961-7
}}
</ref>

<ref name="Part I">
{{cite web | last = Thomas | first = Kathryn A. | author2 = Hansen, Monica| author3 = Seger, Cristoph | title = Part I: Vegetation of Petrified Forest National Park, Arizona | url = http://sbsc.wr.usgs.gov/products/spotlight/petrified/part_1/PartI_Veg.pdf | pages = 1–2 | publisher = United States Geological Survey | year = 2003 | access-date = October 14, 2010 | archive-url = https://web.archive.org/web/20150209133201/http://sbsc.wr.usgs.gov/products/spotlight/petrified/part_1/PartI_Veg.pdf |archive-date = February 9, 2015 | url-status = live
}}
</ref>

<ref name="NPS geology">
{{cite web | title = Geology and the Painted Desert | publisher = National Park Service | url = http://www.nps.gov/pefo/upload/Geology2006.pdf | year = 2006 | access-date = October 1, 2010 | archive-url =https://web.archive.org/web/20121107073112/http://www.nps.gov/pefo/upload/Geology2006.pdf | archive-date = November 7, 2012 | url-status = live
}}
</ref>

<ref name="NPS stone trees">
{{cite web | title = Trees to Stone | publisher = National Park Service | url = http://www.nps.gov/pefo/planyourvisit/upload/TreestoStone2006.pdf | year = 2006 | access-date = October 3, 2010 | archive-url =https://web.archive.org/web/20150907234346/http://www.nps.gov/pefo/planyourvisit/upload/TreestoStone2006.pdf | archive-date = September 7, 2015 | url-status = live
}}
</ref>

<ref name="NPS weather">
{{cite web | title = Petrified Forest Weather | publisher = National Park Service | url = http://www.nps.gov/pefo/naturescience/weather.htm |year = 2014 | access-date = October 17, 2014 | archive-url = https://web.archive.org/web/20131023161319/http://www.nps.gov/pefo/naturescience/weather.htm |archive-date = October 23, 2013 | url-status = live
}}
</ref>

<ref name="NPS history">
{{cite web
 |title=History
 |publisher=National Park Service
 |url=http://www.nps.gov/pefo/planyourvisit/loader.cfm?csModule=security/getfile&PageID=245746
 |format=PDF
 |year=2007
 |access-date=October 5, 2010
 |archive-url=https://web.archive.org/web/20120219062300/http://www.nps.gov/pefo/planyourvisit/loader.cfm?csModule=security%2Fgetfile&PageID=245746
 |archive-date=February 19, 2012

}}
</ref>

<!--  <ref name="Research activities">
{{cite web | title = Research Activities | publisher = National Park Service | url = http://www.nps.gov/pefo/naturescience/research-activities.htm | year = 2007 | access-date = October 16, 2010 |archive-url=https://web.archive.org/web/20151007164158/http://www.nps.gov/pefo/learn/nature/research-activities.htm|archive-date=October 7, 2015|url-status=live
}}
</ref>-->

<ref name="NPS grassland">
{{cite web | title = Grassland | publisher = National Park Service | url = http://www.nps.gov/pefo/planyourvisit/upload/Grassland03w.pdf | year = 2004 | access-date = October 6, 2010 | archive-url=https://web.archive.org/web/20121107080637/http://www.nps.gov/pefo/planyourvisit/upload/Grassland03w.pdf | archive-date= November 7, 2012 | url-status=live
}}
</ref>

<ref name="NPS mammals">
{{cite web | title = Mammals | publisher = National Park Service | url = http://www.nps.gov/pefo/planyourvisit/upload/Mammals04w.pdf | year = 2004 | access-date = October 6, 2010 }}
</ref>

<ref name="NPS modern reptiles">
{{cite web | title = Modern Reptiles | publisher = National Park Service | url = http://www.nps.gov/pefo/planyourvisit/upload/Reptile.pdf | year = 2004 | access-date = October 6, 2010 | archive-url = https://web.archive.org/web/20121107080650/http://www.nps.gov/pefo/planyourvisit/upload/Reptile.pdf | archive-date = November 7, 2012 | url-status = live
}}
</ref>

<ref name="NPS amphibians">
{{cite web | title = Modern Amphibians | publisher = National Park Service | url = http://www.nps.gov/pefo/planyourvisit/upload/Amphibians.pdf | year = 2004 | access-date = October 6, 2010 | archive-url = https://web.archive.org/web/20121107080657/http://www.nps.gov/pefo/planyourvisit/upload/Amphibians.pdf |archive-date = November 7, 2012 | url-status = live
}}
</ref>

<ref name="NPS birds">
{{cite web | title = Birds | publisher = National Park Service | url = http://www.nps.gov/pefo/planyourvisit/upload/Birds2004w.pdf | year = 2004 | access-date = October 7, 2010 | archive-url = https://web.archive.org/web/20121107080734/http://www.nps.gov/pefo/planyourvisit/upload/Birds2004w.pdf | archive-date = November 7, 2012 | url-status = live
}}
</ref>

<ref name="Things to Know">
{{cite web | title = Things To Know Before You Come | publisher = National Park Service | url = http://www.nps.gov/pefo/planyourvisit/things2know.htm | year = 2010 | access-date = October 9, 2010
}}
</ref>

<ref name="Backpacking">
{{cite web | title = Backpacking | publisher = National Park Service | url = http://www.nps.gov/pefo/planyourvisit/backpacking.htm | year = 2009 | access-date = October 9, 2010 | archive-url = https://web.archive.org/web/20150228155630/http://www.nps.gov/pefo/planyourvisit/backpacking.htm |archive-date=February 28, 2015 | url-status = live
}}
</ref>

<ref name="Trails">
{{cite web | title = Trails | publisher = National Park Service | url = http://www.nps.gov/pefo/planyourvisit/trails.htm | year = 2009 | access-date = October 9, 2010 | archive-url = https://web.archive.org/web/20150920075851/http://www.nps.gov/pefo/planyourvisit/trails.htm | archive-date = September 20, 2015 | url-status = live
}}
</ref>

}}

== Works cited ==
{{refbegin}}
* {{cite book | last = Ash | first = Sidney | year = 2005 | title = Petrified Forest: A Story in Stone | edition = 2nd rev. | publisher = Petrified Forest Museum Association | location = Petrified Forest National Park, Arizona | isbn = 978-0-945695-11-0 | ref = {{sfnRef|Ash}} }}
* {{cite book | last = Jones | first = Anne Trinkle | year = 1993 | title = Stalking the Past: Prehistory at the Petrified Forest | publisher = Petrified Forest Museum Association | location = Petrified Forest National Park, Arizona | isbn = 978-0-945695-04-2 | ref = {{sfnRef|Jones}} }}
* {{cite book | last1 = Hansen | first1 = Monica L. | last2 = Thomas | first2 = Kathryn A. | year = 2006 | chapter = The Flora of a Unique Badland and Arid Grassland Environment: Petrified Forest National Park, Arizona | editor1-last = Parker | editor1-first = William G | editor2-last = Thompson | editor2-first = Patricia A. | title = A Century of Research at Petrified Forest National Park: Bulletin No. 63 | publisher = Museum of Northern Arizona | location = Flagstaff, Arizona | isbn = 978-0-89734-133-2 | ref = {{sfnRef|Hansen & Thomas}} }}
* {{cite book | last1 = Van Riper | first1 = Charles III | last2 = Lamow | first2 = Marg | year = 2006 | chapter = A 2006 Bird Checklist for Petrified Forest National Park | editor1-last = Parker | editor1-first = William G | editor2-last = Thompson | editor2-first = Patricia A. | title = A Century of Research at Petrified Forest National Park: Bulletin No. 63 | publisher = Museum of Northern Arizona | location = Flagstaff, Arizona | isbn = 978-0-89734-133-2 | ref = {{sfnRef|Van Riper & Lamow}} }}
{{refend}}

== External links ==
{{Sister project links|wikt=no|commonscat=Petrified Forest National Park|b=no|n=no|q=no|s=no|v=no|voy=Petrified Forest National Park|species=no|d=no}}
* {{Official website|https://www.nps.gov/pefo/}}
* [http://www.nps.gov/history/nr/travel/amsw/ American Southwest], National Park Service ''Discover Our Shared Heritage'' travel itinerary
* [http://repository.azgs.az.gov/uri_gin/azgs/dlio/1487 Geologic map of PEFO], Arizona Geological Survey
* [[Historic American Engineering Record]] (HAER) documentation, filed under Holbrook, Navajo County, AZ:
** {{HAER |survey=AZ-13 |id=az0233 |title=Rio Puerco Bridge, Mainline Road spanning Rio Puerco |photos=29 |data=23 |cap=3 |link=no}}
** {{HAER |survey=AZ-58 |id=az0476 |title=Petrified Forest National Park Roads and Bridges |photos=29 |color=5 |data=60 |cap=3 |link=no}}
** {{HAER |survey=AZ-59 |id=az0477 |title=Jim Camp Wash Bridge, Spanning Jim Camp Wash at Route 10 |photos=3 |color=1 |data=6 |cap=1 |link=no}}

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