Comanche National Grassland.

We also hiked at the Comanche National Grassland, which includes 440,000 acres in southeastern Colorado. 150 million years ago, during the Jurassic period, dinosaurs walked here; 1,500 years ago, ancient peoples created rock art on the canyon walls. That makes Santa Fe trail history seem recent...between 1821 and 1880 came the covered wagons, the caravans. But life had thrived on the grasslands for thousands of years.