This field trip was part of the October 2000 Earth Science Week. PDF download. FT-00-02D
From the Introduction:
The Purgatoire River rises in the Rocky Mountains west of Trinidad, Colorado, and flows northeast across the southern High Plains for a distance of about 150 miles to its confluence with the Arkansas River just east of Las Animas. Although a sparsely populated and little known area, the Purgatoire Valley is one of the most beautiful locations on the High Plains. This guidebook will focus on the story of one small stretch of this valley known as Picket Wire Canyonlands, an area containing the largest dinosaur tracksite currently known in North America. The Picket Wire Canyonlands lie within the Comanche National Grasslands, approximately 23 miles south of the town of La Junta in southeastern Colorado. The area, currently managed by the USDA Forest Service, is rich in history, flora and fauna, and above all has a unique paleontological heritage. The tracksite is located in the northern portion of the Canyonlands, and the track-bearing rock is situated both within, and on the banks of the Purgatoire River.
See also A Dash with Dinosaurs RockTalk entry.