Length: 11 miles round trip, 300 vertical feet
Difficulty: Hard
Why We Love It: It’s a peaceful out-and-back hike to a prehistoric site where 25-ton Apatosauruses once roamed.
When to Go: Spring and fall
Pre-hike Buzz: Stop by The Barista in La Junta for a post-hike Prairie Schooner or Rambler panini, paired with a cool mocha frappe.
Restrooms: Vault toilets at trailhead
Distance from Denver: About 200 miles
Dogs: Not allowed

About 150 million years ago, during the Jurassic Period, a large, shallow lake stretched across much of southern Colorado. Its muddy shoreline teemed with dinosaurs, including numerous long-necked Apatosauruses (formerly called Brontosauruses), herbivorous dinosaurs that grew up to 75 feet long and weighed up to 25 tons, as well as smaller, fiercer Allosauruses. More than 1,300 of these creatures’ ancient tracks are still exposed along the banks of the Purgatoire River, making it North America’s largest dinosaur tracksite.

A fossilized Allosaurus track. Photo by Lon Abbott

From the Withers Canyon trailhead, this route descends about 250 feet into the chasm and follows a tributary to its confluence with the Purgatoire River, which runs from the Sangre de Cristo Range to where it joins the Arkansas River near the Kansas border. The route winds past stubby juniper trees and sandstone cliffs that make it seem as if you’re in southern Utah—but without the crowds. Much like in Utah, however, it’s a good idea to wear pants to protect your skin from the many cacti and other prickly things scattered along the route.

After you reach the Purgatoire River, the trail turns right to follow a dirt road that keeps going along the riverbank as you head upstream. Don’t count on the river for water supplies, however, as its sandy bottom is often dry. Temperatures in this part of the state can be very hot, and there’s no shade, so heat stroke is a serious concern. Be sure to bring plenty of water and a sunhat, and be prepared for whatever weather is in the forecast.

After about four miles, the trail reaches the remains of the Dolores Mission and Cemetery, which served as an important focal point of a small Hispanic community that lived in this isolated area in the late 1800s. About 1.5 more miles beyond these ruins, you arrive at the tracksite, where dinosaur footprints are exposed on both sides of the river.

The best examples are located on the river’s near side. These include distinctive, three-toed prints made by a carnivorous Allosaurus. Also visible are hundreds of Apatosaurus prints, including in trackways—a series of footprints made by a moving animal.

One of the features that makes this site so unusual are two long, parallel trackways, made by two massive Apatosauruses who once strolled side by side along the ancient shoreline. Paleontologists value trackways because they’re able to provide much more information than individual footprints, such as the direction a dinosaur was heading and the speed at which it was walking when it ambled across the very different landscape that existed in the spot 150 million years ago.

If you’d rather not hike this far, it’s also possible to bike to the tracksite, but it’s very important to bring spare tubes due to the large number of prickly plants along the way. The U.S. Forest Service hopes to resume guided auto tours, which are typically available each Saturday in May, June, September, and October, this autumn. You can call Comanche National Grassland at 719-384-2181 for more information.

Picket Wire Canyon in southeastern Colorado’s Comanche National Grasslands. Photo by Lon Abbott

Getting there: From La Junta, head south on Colorado Highway 109 for 14 miles, then turn right (west) onto County Road 802 and follow it for eight miles. Next, turn left on County Road 25 and drive south for six miles to reach Picket Wire Corrals. At the corrals, turn left onto Forest Road 2185 and take this east for about 3.5 miles, following the signs to the Withers Canyon Trailhead.

Terri Cook
Terri Cook
Terri Cook is an award-winning freelance writer based in Boulder. More of her work can be found at down2earthscience.com.