National Parks › Desert Southwest › Petrified Forest

Petrified Forest National Park

Arizona · Established December 9, 1962

Stone logs, banded badlands, and 200 million years laid open to the sky

Area: 221,390 acres
Established: December 9, 1962
Recreation visits: 315,951 / yr
State: Arizona
Highest point: Pilot Rock, 6,230 ft (1,900 m)
Lowest point: Puerco River, 5,340 ft (1,630 m)

Petrified Forest Weather Forecast

Loading the National Weather Service forecast for Petrified Forest…

Seven-day outlook at the park's reference point (34.984, -109.788). Elevation changes everything in the mountains — expect colder, windier and wetter conditions on high ground.

Map of Petrified Forest National Park

The Park

On the high grasslands of northeastern Arizona, the ground is littered with logs that ring like pottery when tapped. They are trees that grew in the Late Triassic, buried in river mud and slowly turned to quartz, their bark and growth rings preserved in reds, yellows, and smoky purples. Petrified Forest National Park guards one of the richest concentrations of this fossil wood anywhere, along with the striped badlands of the Painted Desert that frame it to the north.

The park was proclaimed a national monument early in the twentieth century and became a national park on December 9, 1962. Today it covers about 221,390 acres. A single road runs its length, from the Painted Desert rim past pueblo ruins and petroglyph panels to the log-strewn flats of the Rainbow Forest, and it crosses the old alignment of Route 66 along the way.

Geography

Petrified Forest sits on the southern Colorado Plateau, at an average elevation of about 5,400 feet. Its northern half belongs to the Painted Desert, a country of rounded clay hills, flat-topped mesas, and lava-capped points that look out over broad washes. The southern half is gentler grassland broken by blue and gray badland knolls and the scattered log deposits for which the park is named.

The Puerco River cuts east to west across the middle of the park and marks its lowest ground. North of it, Lithodendron Wash drains a roadless wilderness that runs up toward Pilot Rock, the park's high point. Interstate 40 and the rail line cross the park near the Painted Desert entrance, while the southern gate opens toward Holbrook on U.S. Route 180.

Landmarks

Pilot RockPeak · 6,230 ftA dark volcanic knob in the northern wilderness and the highest ground in the park.
Chinde PointAreaA rim-top overlook at the northern end of the park road with long views across the Painted Desert.
Kachina PointAreaThe trailhead into the Painted Desert Wilderness, perched on the rim beside the Painted Desert Inn.
Painted Desert InnAreaA Pueblo Revival landmark on the rim, now a museum overlooking the badlands.
Tawa PointAreaAn overlook where red mudstone hills spill away below a basalt-capped rim.
Lithodendron WashRiverA broad sandy wash, dry most of the year, winding through the northern wilderness.
Puerco PuebloAreaThe remains of a masonry pueblo above the Puerco River, surrounded by petroglyph-covered boulders.
Newspaper RockAreaA cluster of sandstone blocks densely pecked with hundreds of petroglyphs.
The TepeesAreaConical badland hills banded in blue, gray, and maroon mudstone of the oldest Chinle layers.
Blue MesaPlateauA mesa of bluish and purple badlands where a paved loop descends among weathering logs.
Agate BridgeArchA petrified log that spans a small ravine, its sandstone footing long since washed away beneath it.
Jasper ForestAreaAn overlook above a valley floor strewn with logs eroded out of the slopes above.
Crystal ForestAreaA log field once prized for the quartz and amethyst crystals lining hollow trunks.
Rainbow ForestAreaThe southern hub of the park, where the Giant Logs trail begins behind the museum.
Long LogsAreaOne of the densest accumulations of fossil logs in the park, many lying end to end.
Agate HouseAreaA small pueblo built from blocks of petrified wood, partly reconstructed in the 1930s.

Geology

Roughly 225 to 205 million years ago, this corner of Arizona lay near the equator on the supercontinent Pangaea. Rivers flowing across a warm, seasonally wet lowland piled up sand, gravel, and mud, and volcanoes far to the southwest dusted the basin with ash. That accumulation became the Chinle Formation, whose soft mudstones and harder sandstones make up almost everything a visitor sees in the park today.

Floods toppled tall conifers and buried them in channel sands rich in volcanic debris. Groundwater carrying dissolved silica seeped through the logs, and over long ages quartz filled and replaced the wood cell by cell. Traces of iron, manganese, and other elements tinted the stone the reds, yellows, and blacks that give the logs their color. Much of the wood has long been catalogued under the fossil name Araucarioxylon arizonicum.

After the Chinle was laid down, the record here goes quiet for about 190 million years; whatever sediments once covered it were stripped away. Beginning around 60 million years ago the Colorado Plateau was lifted high, and between about 8 and 4 million years ago lakes, streams, and small volcanoes deposited the Bidahochi Formation, whose lava flows now cap the Painted Desert rim.

Erosion finishes the story. The Chinle mudstones are full of bentonite, a clay made from volcanic ash that swells when wet and shrinks and cracks when dry. Each thunderstorm sheds a skin of it downslope, carving badlands and freeing fresh logs from the hillsides while older ones break apart in the washes.

Deep time

227–225 million years agoRivers deposit the red siltstones and conglomerates of the Mesa Redondo Member, the oldest Chinle layer exposed in the park.
About 220–225 million years agoMuddy floodplains lay down the blue, gray, and purple mudstones of the Blue Mesa Member.
About 216 million years agoSandy, braided channels of the Sonsela Member bury many of the logs now seen in the Rainbow Forest area.
About 213 million years agoThe reddish mudstones and sandstones of the Petrified Forest Member accumulate, preserving abundant wood.
About 205 million years agoThe Owl Rock Member's pinkish mudstones and thin limestones close the Chinle record.
About 60 million years agoUplift of the Colorado Plateau begins, setting the stage for deep erosion.
8–4 million years agoLake, stream, and volcanic deposits of the Bidahochi Formation form the lava-capped Painted Desert rim.
Last 1.8 million yearsWind and water rework the land into dunes, alluvium, and badlands, exposing buried logs.

The rocks

Mesa Redondo Member (Chinle Formation)Late Triassic, 227–225 Ma
Dark red siltstones and sandy conglomerates visible low in the Tepees area.
Blue Mesa Member (Chinle Formation)Late Triassic, about 220–225 Ma
Gray, blue, purple, and green mudstones with thin sandstones, including the Newspaper Rock sandstone.
Sonsela Member (Chinle Formation)Late Triassic, about 216 Ma
A three-part package of cross-bedded sandstone and mudstone that holds major log deposits.
Petrified Forest Member (Chinle Formation)Late Triassic, about 213 Ma
Red mudstones and brown sandstones forming much of the Painted Desert and rich in fossil wood.
Owl Rock Member (Chinle Formation)Late Triassic, about 205 Ma
Pinkish-orange mudstone with thin limestone and lenses of selenite gypsum near the northern boundary.
Bidahochi FormationMiocene–Pliocene, 8–4 Ma
Fine lake and river sediments with volcanic ash and resistant lava flows.
Quaternary depositsPleistocene–Holocene
Windblown sand and stream alluvium draped over the older bedrock.

Trees, Plants & Ecosystems

451vascular plant species recorded

Shortgrass grasslandUplands throughout the park
Blue grama, galleta, and needlegrasses cover the gentle uplands, one of the better-preserved native grasslands left in Arizona.
Desert shrublandSandy flats and saline soils
Saltbush, rabbitbrush, and Mormon tea gather on saltier soils and sandy flats.
BadlandsPainted Desert and Blue Mesa
Bentonite hills swell and crack so constantly that few plants take hold, though lizards and ravens range across them.
Riparian corridorsPuerco River and springs, near 5,340 ft
Cottonwoods and willows line stretches of the Puerco River and springs, drawing migrating birds.
Juniper–shrub pocketsRims and mesa edges
Small stands of juniper and cliffrose cling to rims and mesa edges.

Trees

Fremont cottonwoodPopulus fremontiiThe tallest living tree in the park, marking water along the Puerco River.
Rio Grande cottonwoodPopulus deltoides ssp. wislizeniA broad-crowned cottonwood of wash bottoms that turns bright gold in October.
Goodding's willowSalix gooddingiiA tree willow that shares riverbanks with the cottonwoods.
Coyote willowSalix exiguaA thicket-forming willow that holds sandbars in place.
Oneseed juniperJuniperus monospermaA shrubby juniper scattered along rims and rocky slopes.
Two-needle pinyonPinus edulisRare here, a reminder that woodlands lie just upslope of the park.
Chinese tamariskTamarix chinensisAn invasive saltcedar that crowds riverbanks and is a target of removal work.

Wildflowers, shrubs & other plants

Blue gramaBouteloua gracilisA low bunchgrass whose seed heads curl like eyelashes, the backbone of the grassland.
GalletaPleuraphis jamesiiA tough, drought-hardy grass that spreads by runners across sandy flats.
Indian ricegrassAchnatherum hymenoidesA graceful bunchgrass with airy, seed-tipped panicles, favored on sandy soils.
Needle-and-threadHesperostipa comataNamed for its long, twisting awns that drill seeds into the ground.
Fourwing saltbushAtriplex canescensA gray shrub with papery four-winged fruits, browsed by pronghorn.
Rubber rabbitbrushEricameria nauseosaA late-season shrub that floods washes with yellow bloom.
Green Mormon teaEphedra viridisA leafless, jointed shrub of bright green stems.
Narrowleaf yuccaYucca angustissimaIts tall stalks of creamy bells rise from rosettes of slender leaves in late spring.
Whipple's chollaOpuntia whippleiA low, spiny cholla that flowers yellow in early summer.
Smallflower globemallowSphaeralcea parvifoliaApricot-orange mallow blossoms that brighten roadsides.
Tufted evening primroseOenothera caespitosaLarge white flowers that open at dusk and fade pink by morning.
Wholeleaf Indian paintbrushCastilleja integraScarlet bracts among the grasses after spring moisture.
Sand sagebrushArtemisia filifoliaA silvery, threadleaf sage that anchors sandy soils.
Skunkbush sumacRhus trilobataA three-leaflet shrub with tart red berries and fall color on rims.

Wildlife

32mammals
221birds
16reptiles
7amphibians

Mammals

PronghornAntilocapra americanaThe fastest runner in North America, often seen grazing along the park road.
CoyoteCanis latransCommon across grassland and badland, heard at dawn and dusk.
Kit foxVulpes macrotisA small, big-eared fox that hunts rodents at night.
BobcatLynx rufusA secretive cat of washes and broken country.
Mule deerOdocoileus hemionusBrowses in the brushier drainages and near the river.
ElkCervus elaphusAn occasional visitor wandering down from higher country.
Gunnison's prairie dogCynomys gunnisoniColonies dot the grasslands and feed hawks, badgers, and coyotes.
Black-tailed jackrabbitLepus californicusIts huge ears shed heat on summer afternoons.
Desert cottontailSylvilagus auduboniiCommon near shrub cover around developed areas.
Ord's kangaroo ratDipodomys ordiiA nocturnal seed-eater that hops on long hind legs and rarely drinks.
White-tailed antelope squirrelAmmospermophilus leucurusA quick ground squirrel that carries its tail over its back like a parasol.

Birds

Common ravenCorvus coraxThe park's most conspicuous bird, riding updrafts along the rim.
Golden eagleAquila chrysaetosHunts rabbits and prairie dogs over open country.
Red-tailed hawkButeo jamaicensisOften perched on utility poles near the road.
Prairie falconFalco mexicanusA pale, fast falcon that nests on cliffs and hunts low over grass.
American kestrelFalco sparveriusA small falcon that hovers in place above the grassland.
Burrowing owlAthene cuniculariaUses old prairie dog burrows and stands sentinel by day.
Greater roadrunnerGeococcyx californianusA ground cuckoo that sprints after lizards in the shrubland.
Horned larkEremophila alpestrisFlocks of these streaked songbirds flush from roadsides year-round.
Western meadowlarkSturnella neglectaIts flutelike song carries across the grass in spring.
Rock wrenSalpinctes obsoletusA busy little wren that bobs on badland boulders and log piles.
Sage thrasherOreoscoptes montanusA long-singing thrasher of the shrub flats.
Common nighthawkChordeiles minorBooming display flights fill summer evenings.

Reptiles & amphibians

Eastern collared lizardCrotaphytus collarisA big-headed lizard that basks on rocks and can run on its hind legs.
Greater short-horned lizardPhrynosoma hernandesiA flat, spiny lizard well camouflaged against gravel.
Side-blotched lizardUta stansburianaOne of the most commonly seen lizards on warm days.
Plateau fence lizardSceloporus undulatusA spiny lizard that does push-up displays from logs and rocks.
GophersnakePituophis cateniferA large, harmless constrictor that hunts rodents in burrows.
Prairie rattlesnakeCrotalus viridisVenomous and generally shy; watch where you step off trail.
Plains spadefootSpea bombifronsStays buried until summer rains fill ephemeral pools, then breeds in a rush.
Tiger salamanderAmbystoma tigrinumA surprising amphibian of stock tanks and seasonal ponds.

Species totals are the park's certified NPSpecies checklist (occurrence: present).

Climate & When to Visit

Petrified Forest has a semi-arid high-desert climate, with only about 10 inches of precipitation a year. Its elevation keeps summers from the extremes of the low desert, but afternoons can still pass 100°F, while winter nights routinely fall well below freezing. Humidity is usually low, so the air cools quickly after sunset.

Much of the year's moisture arrives in two ways: occasional light snows in winter, and short, violent thunderstorms during the summer monsoon, which can bring lightning, hail, and sudden runoff through the washes. Spring is the windiest season, when gusty southwest winds lift sand and dust across the open grassland.

Spring
Mild days and cold nights, with frequent strong winds and blowing dust; wildflowers depend on winter moisture.
Summer
Hot, bright mornings give way to afternoon thunderstorms in the monsoon, bringing lightning and brief downpours.
Autumn
Often the calmest and most comfortable season, with clear skies, cooler air, and golden cottonwoods along the river.
Winter
Crisp and sunny between storms, with nights below freezing and occasional light snow that dusts the badlands.

Weather hazards

Lightning: Exposed mesas and open grassland offer no shelter, so head to your vehicle when thunder is heard.
Heat and dehydration: There is little shade on any trail, so carry more water than you expect to need in summer.
Flash floods: Monsoon storms can send sudden water down dry washes like Lithodendron Wash, even from rain miles away.
High winds: Spring gusts can raise blinding dust and make driving and hiking unpleasant.
Winter ice: Snow and ice can briefly slick the park road and rim trails on cold mornings.

Petrified Forest Questions

When is the best time to visit Petrified Forest National Park?

Autumn is usually the most pleasant season, with mild temperatures, calm air, and clear light. Spring is also comfortable but often windy, while summer brings hot days and afternoon thunderstorms.

How did the wood become petrified?

Trees that fell into Triassic rivers were buried quickly in sediment full of volcanic ash. Silica-rich groundwater soaked through them over long periods, and quartz gradually filled and replaced the wood, with trace minerals adding the colors.

How old are the petrified logs?

The logs come from the Late Triassic Chinle Formation, deposited roughly 225 to 205 million years ago, when the region lay near the equator on the supercontinent Pangaea.

What is the weather like at Petrified Forest?

It is a dry high-desert grassland receiving about 10 inches of precipitation a year. Summers can exceed 100°F with monsoon storms, and winters bring freezing nights and occasional snow.

What wildlife might I see?

Pronghorn, coyotes, and ravens are the most commonly spotted animals, and collared lizards and prairie dogs are active on warm days. Early morning and evening are best, especially in the grasslands south of the Puerco River.

Can I take a piece of petrified wood home?

No. Collecting any petrified wood, rock, or fossil inside the park is prohibited. Legally collected petrified wood from private land is sold at shops outside the park.

Why are the Painted Desert badlands striped?

The stripes are layers of Chinle mudstone and sandstone deposited in different ancient environments. Iron and other minerals in each layer, along with how well the ancient soils drained, produce the reds, purples, grays, and blues.

More parks in the Desert Southwest

← Olympic National Park Pinnacles National Park →

Sources: www.nps.gov · www.nps.gov · www.nps.gov · www.nps.gov · irmaservices.nps.gov · en.wikipedia.org · Official NPS site