The Colorado rock floor known for keeping North America’s longest stretch of dinosaur tracks just got longer.

The U.S. Forest Service recently reported crews cleaning 6 inches of mud and debris from flooding in Picket Wire Canyonlands, the rugged expanse along the southeast plains. In that process with shovels and excavators, more footprints were uncovered, said Bruce Schumacher, a Forest Service paleontologist.

He said the fossilized tracks are those belonging to creatures of the same family of Brontosaurus — resulting in the round steps that people have walked with for decades, extending across an ancient seabed.

Schumacher said between 100 to 150 tracks are being added to the inventory of 2,000-plus.

“Every track down there is a national treasure,” said John Linn, Comanche National Grassland district ranger. “I hiked it just yesterday actually. … It never ceases to amaze me. I’m always overcome with awe when I stand in those tracks that are 150 million years old.”

Since the tracks were scientifically documented in the 1980s, Schumacher said about 800 additional tracks have been mapped. That has largely been through the occasional cleanup like this year’s that unearthed the latest stretch.

Whenever the Purgatoire River floods in such a way that the tracks are covered with sediment, volunteers and specialists bring their tools and machines and return the tracks to daylight. That’s to keep them in view for visitors who make the long hike on their own or tag along for seasonal Forest Service tours.

This summer, “there was an event that flooded an area that had not yet been mapped and recorded,” Schumacher explained.

One track was found, he said. And then another, and then another. “And off you go to the races,” he said.

The tracks “could continue for a long, long time,” Schumacher said. “But we’ve kind of reached a point where we’ve got a good amount exposed. At least I feel like we’re at a place to continue to manage it as it is.”

The tracks can be reached in an 11.2-mile round trip hike from Withers Canyon trailhead. Area closed to automobiles except for official tours, which are expected to return in spring. More information: https://bit.ly/30kjqs8