Dinosaur National Monument straddles the Colorado-Utah border. The famous quarry in the Morrison Formation that preserves more than 1,000 Jurassic-aged fossils lies in the Utah portion of the monument. Visitors to Colorado’s remote portion of the monument are rewarded with views of the spectacular canyons of the entrenched Yampa and Green Rivers.

The Quarry Visitor Center is often the first stop. With fantastic fossil exposures, it is worth your time to visit the center. The Quarry Visitor Center is about 3.5 hours east from Salt Lake City, UT, and about 2.5 hours north of Grand Junction, Colorado.

Geology

Confluence of the Yampa and Green Rivers

The incision of the rivers did not begin until around 9 to 6 million years ago, when regional uplift caused the gravity-driven water to carve downward (water always flows downhill!). Once the rivers became entrenched in the resistant sandstone, there was no other way to move than to slice downward through many layers of sedimentary and volcanic rock. The Canyon of Lodore on the Green River reaches into 1.1-billion-year-old sandstones and shales of the Uinta Mountain Group, the oldest rock unit exposed in the monument.

Echo Park, 37 miles north of the Canyon Visitor Center near the town of Dinosaur, provides access to Steamboat Rock at the confluence of the Yampa and Green Rivers. The high walls of Steamboat Rock are the Weber Sandstone, a massive, thickly bedded, fine-grained yellowish rock that is the primary cliff-forming unit in Dinosaur National Monument.

The sandstone was deposited as ancient sand dunes in middle Pennsylvanian time and is as much as 1,150 feet thick! Look for cross beds formed by winds blowing sand in the dunes. At the confluence, the different colored waters of the two rivers are visible as they join and mix.

The Green River’s water is largely blue and clear,  as much of the Green River sediments settled out in the reservoir upstream from Flaming Gorge Reservoir dam. In contrast, the more sediment-rich waters of the Yampa tend to be brown to reddish. Flaming Gorge is also an incredible place to visit! The rivers continue to deepen their incredible canyons with each passing year.

Know before you go

To get to Echo Park, you will drive on both paved and unpaved roads. The last 13 miles of the approach to Echo Park are on graded dirt roads, which are dangerous and impassable in bad conditions. Navigating a series of narrow switchbacks with high exposure is also required, and dangerous in wet or icy conditions. Check road conditions with the visitor center before you go!

Picnic tables and vault toilets are available at Echo Park. Water is seasonally available (check with the visitor center!), but just to be safe, bring extra water as well as your food and other equipment. Be sure to pack everything out with you!

What is your favorite part of Dinosaur National Monument?

Fossils? Hikes? River rafting? Desert aesthetic? What makes you smile when you remember your last visit to Dinosaur – or what motivates you to plan your next trip?

You can read more about the geology of Echo Park, Dinosaur National Monument, and many other sites in “Colorado Rocks: A Guide to Geologic Sites in the Centennial State” available on this website and anywhere books are sold (Amazon, Barnes & Noble, etc.)