Southeast of Vernal in the Ashley National Forest, the Dinosaur Nationa Monument Loop is a 20 mile route through one of the largest dinosaur graveyards in the world. It loops through the high desert, over stretches of slickrock, and provides scenic overlooks of this spectacular eroded area.
To reach the mountain biking trailhead from Vernal, head east on US 40 for about 20 miles to the town of Jensen and the turnoff to the monument (UT 149). Head north and enter the park, saving your receipt. Park at the lower parking lot near the entrance station. Begin pedaling up the hill to the quarry. After about 0.5 miles, head east on the monument road. After about 5.5 miles, mountain bike ride across the bridge spanning the Green River. Continue for 2.4 miles. At the plank fence just past auto tour marker #10, take a right onto the jeep road. The next mile is a steady climb that drops along sandstone ledges to the bottom of a creek and passes through a wire gate. The trail climbs over some slickrock sections here and provides views of Split Mountain to the north. After descending to the bottom of another draw, the trail climbs again for about 1 mile. This section is followed by about 4 miles of rolling hills. The dirt road eventually merges with pavement. Turn left and return to US 40. Turn right (west) on the highway and return to Jensen. At Jensen, turn right and follow UT 149 back to the monument and your vehicle.
Overall, Dinosaur National Monument Loop is the 52nd most popular mountain bike trail of all 73 mountain biking rides in Utah.