Pike & San Isabel National Forests
Cimarron & Comanche National Grasslands

 

 

 

150 millions years ago, hundreds of dinosaurs inhabited the area that is now the Purgatoire River Valley. Southeastern Colorado at that time was dominated by a vast freshwater lake. As the dinosaurs plodded through the mud along the edge of this lake, they left behind vast trails of footprints in the soupy muck. Later, these muddy flats were buried and turned to stone. Today, over 1,300 of these footprints are exposed at the Picketwire Canyonlands dinosaur tracksite.