Dinosaur National Monument

National Monument 210,844 acres Est. 1915 National Park Service

Overview

Dinosaur is really two monuments sharing a name. On the Utah side, near Jensen, is the thing it was named for: a tilted sandbar of Jurassic river deposit, quarried into a wall where roughly 1,500 dinosaur bones stand out in relief, sheltered now under the Quarry Exhibit Hall. But the far larger part — added in 1938 — is river country straddling the Utah-Colorado line, where the Green River cuts straight through the flank of the Uinta Mountains in the Gates of Lodore and Split Mountain, and the Yampa, the last substantially wild major river in the Colorado system, joins it beneath the sheer face of Steamboat Rock at Echo Park. That confluence is also a battlefield: a proposed dam at Echo Park in the early 1950s was defeated in a fight that helped launch the modern conservation movement and left the Yampa flowing. For Desert Maritime, Dinosaur is a permit-river anchor — Lodore, Split Mountain, and the Yampa are lottery-permit multi-day runs — wrapped around one of the best fossil sites on Earth.

Getting in

Entrance fee: $25/vehicle (7-day) · $15/person · $45 annual pass · America the Beautiful pass accepted
7-day pass. Entrance fee does not cover camping or river-permit fees.
Timed entry: Not required (as of 2026-07-12)
No timed-entry reservation. River permits are the constraint here, not park entry.
Hours: Monument grounds open year-round; visitor centers and the Quarry Exhibit Hall run seasonal hours.

Permits & reservations

Multi-day river permits (Green — Gates of Lodore & Split Mountain; Yampa) — Recreation.gov (weighted lottery). Private multi-day trips are awarded by a competitive weighted lottery with a fixed winter application window; results in late winter. Verify current dates each year. Reserve

Visitor centers

Quarry Visitor Center & Exhibit Hall — Utah side near Jensen; access to the fossil wall (seasonal shuttle in peak season).
Canyon Visitor Center — Colorado side, in the town of Dinosaur; gateway to Harpers Corner Road.

When to go

Best: May, Jun, Sep, Oct Shoulder: Apr, Jul, Aug

The quarry draws steady family traffic; the river canyons are quiet and permit-limited. Yampa season (May–June) is the busy window for river runners.

River season peaks with snowmelt (May–June for the Yampa). Summer is hot in the canyons; spring and fall are the sweet spots for hiking and driving the rim.

Safety & conditions

Risk level: Medium
Cell service: Spotty
Water: Potable water at visitor centers and developed campgrounds; none on the rivers or backcountry roads — carry and treat your own.
Nearest hospital: Ashley Regional Medical Center, Vernal, UT (nearest to the quarry side).

Hazards

Swift water (high) — Lodore and the Yampa carry serious rapids at snowmelt flows.
Heat (medium) — Canyon bottoms are hot and shadeless in summer.
Road hazard (medium) — Echo Park and Yampa Bench dirt roads are dangerous when wet.
Remoteness (medium) — The canyon side is far from services; the Yampa is a wilderness river.

Cell coverage is spotty to absent in the canyons; river trips are self-supported wilderness.

Activities

Rafting / River

Dinosaur is one of the West's great permit-river destinations: the Gates of Lodore and Split Mountain on the Green, and the wild Yampa. Multi-day, lottery-permitted, and world-class.

Areas: Gates of Lodore (Green); Split Mountain (Green); Yampa Canyon

Season: May–July for the Yampa (snowmelt-dependent); the Green runs a longer, dam-regulated season.

Permit required

Regs: Multi-day river permits are issued by a competitive weighted lottery on Recreation.gov; commercial outfitters hold separate allocations. Verify the current application window each year.

Wildlife & Paleontology

Paleontology first — the Quarry Exhibit Hall's wall of ~1,500 bones — plus bighorn sheep, raptors, and the endangered native fish of the Green and Yampa. Petroglyph and pictograph panels (Fremont) are scattered through the monument.

Season: Quarry open year-round; a seasonal shuttle/tram serves it in peak season.

Hiking

Short trails at the quarry side (Fossil Discovery Trail, Sound of Silence) and river-country walks like the Harpers Corner Trail and the petroglyph routes near Echo Park.

Season: Spring and fall; summer is hot in the canyons.

Carry water; canyon-country trails are hot and exposed.

Scenic Driving

Harpers Corner Road runs out to a rim above the confluence country; the Echo Park and Yampa Bench roads are rugged dirt spurs into the heart of it.

Season: Paved rim road spring–fall; dirt spurs impassable when wet.

Echo Park Road and Yampa Bench Road are dirt, steep in places, and dangerous when wet — check conditions.

Stargazing

Remote, dark canyon skies — the monument runs seasonal night-sky programs and the river camps offer superb stargazing.

Season: Year-round; best on new-moon nights.

Districts

Quarry / Green River (Utah side)

The Quarry Exhibit Hall, Josie Morris cabin, Split Mountain, and the Green River rafting put-ins/take-outs near Jensen, UT.

Access: ~20 minutes east of Vernal, UT via US-40 and UT-149.
Canyon Country (Colorado side)

Harpers Corner Road, the Echo Park overlook and dirt descent to the Green–Yampa confluence, and the Yampa Bench — the big-view, big-river side of the monument.

Access: From the town of Dinosaur, CO via Harpers Corner Road; Echo Park road is dirt and impassable when wet.
Gates of Lodore

The far-north access where the Green enters the monument through a dramatic red gorge — the Lodore Canyon put-in and campground.

Access: Reached from the north via Browns Park; a long, remote approach.

Geology

The Green River cuts straight through the Uinta uplift instead of going around it — the river is older than the mountains and sawed down as they rose (antecedent drainage). The Mitten Park fault, exposed at river level near Echo Park, is a textbook roadside-geology feature.

A river older than the mountains it cuts

The Uinta Mountains are one of the few major east-west ranges in the Rockies, and the Green River runs right through their southern flank — through the Gates of Lodore and out at Split Mountain — rather than detouring around them.

That only happens when the river was already there before the range rose. As the Uintas uplifted, the Green kept its course and cut downward, slicing a gorge through rock that was rising to meet its blade.

The bones in the quarry come from the same story at a different scale: a Jurassic river dumped carcasses on a sandbar, later buried and tilted by the same regional forces, and now re-exposed by erosion.

Lodore and Split Mountain aren't gaps the river found — they're gaps the river made, straight through a rising range.

NPS — Dinosaur National Monument, Geology

Province: Uinta Mountains / Colorado Plateau transition

Rock types: quartzite, sandstone, limestone, shale

Major formations

Uinta Mountain Group quartzite (Proterozoic — Gates of Lodore walls)
Weber Sandstone (Split Mountain, canyon walls)
Morrison Formation (Jurassic — the dinosaur-bearing quarry)

Ecology

Biomes: Colorado Plateau / Uinta Basin desert shrubland; pinyon-juniper woodland; riparian cottonwood galleries along the Green and Yampa; montane forest at higher elevations

Flora

Fremont cottonwood (river corridors)
box elder and sandbar willow
Utah juniper and pinyon pine
sagebrush and greasewood

Fauna

Colorado pikeminnow, razorback sucker, humpback chub — endangered native fish of the Green and Yampa
bighorn sheep
mule deer and elk
peregrine falcon
river otter (localized)

The Yampa's near-natural flow makes it critical habitat for the Colorado River's endangered native fish, whose spawning cues depend on the spring flood the Yampa still delivers.

History

From Earl Douglass's 1909 fossil discovery to the 1938 river-canyon expansion, Dinosaur's most consequential chapter came in the 1950s, when conservationists defeated a dam at Echo Park and helped define how America fights for wild rivers.

Indigenous homelands: Ute, Eastern Shoshone, Fremont culture (extensive petroglyphs and pictographs)

Key events

1909 Paleontologist Earl Douglass discovers the dinosaur quarry near Jensen, Utah.
1915 Dinosaur National Monument established to protect the 80-acre quarry.
1938 Monument expanded to ~210,000 acres to include the Green and Yampa river canyons.
1950–1956 The proposed Echo Park Dam is defeated — a landmark victory for the modern conservation movement; the Yampa stays free-flowing.

Notable figures

Earl Douglass
David Brower

Modern issues

Free-flowing Yampa and native-fish recovery

Status: ongoing

As of: 2026-07-12

The Yampa's near-natural spring flood is central to recovering the Colorado system's endangered native fish; upstream water-development pressure on the Yampa is a recurring conservation issue.

Access & regulations

Roads

Harpers Corner Road — paved. Spring–fall; closed by snow in winter. Paved scenic road to the Harpers Corner trailhead and overlooks.
Echo Park Road — rough dirt. Dry weather only; impassable when wet. Steep dirt descent to the Green–Yampa confluence.

Seasonal closures

Harpers Corner Road and dirt spurs — Winter (snow). Upper roads close with snow; dirt roads impassable when wet year-round.

Accessibility: The Quarry Exhibit Hall and visitor centers are accessible; the fossil wall is reachable without strenuous hiking.