Twentymile Wash Dinosaur Megatrackway
What To See and Do: The Twentymile Wash Dinosaur Megatrackway, located approximately 20 miles southeast of Escalante, in Grand Staircase-Escalante National Monument, was discovered in 1998 by paleontologist Joshua Smith. Over one thousand mapped tracks cover the slickrock surfaces weathered into the Escalante Sandstone Member of the Entrada Formation. This portion of the Entrada, which dates to approximately 160 million years ago, was deposited on the southern margin of a shallow inland sea. At this time, desert conditions prevailed in the Colorado Plateau region and much of the Entrada Formation resulted from deposition of windblown sand. Occasionally, wind scours would remove the dune sand down to the water table and expose flowing water, a rare commodity in this harsh environment. Immediately, dinosaurs would congregate, trampling the sand and leaving the only tangible legacy of their existence. Two types of dinosaurs are clearly evident, a bipedal (walking on two legs) form with sharply clawed, bird-like three-toed feet (Megalosauripus) and a quadrupedal (walked on four legs) form with rounded, elephantine feet (Brontopodus).
Over 800 dinosaur footprints are preserved in the upper part of the Entrada Sandstone. The main 2-meter-thick track-bearing horizon crops out at the top of a 400-meter-long east/west trending bench, exposing tracks and trackways from multiple levels. Track preservation occurs as dark sediment infillings and as alternating light and dark underprinted sand laminations.
Check out some of the scientific work being done at Twentymile Wash Dinosaur Trackway.
Follow this link to read "Ancient Animal Footprints and Traces in the Grand Staircase-Escalante National Monument, South-Central Utah" by Alden H. Hamblin and John R. Foster, published in 2000 Utah Geological Association Publication 28.
How To Get There: Travelers should at least have a 2WD, high clearance vehicle to travel to this locality.
IMPORTANT! Generally, this road is passable with a 2WD, high clearance vehicle. However, Collet Top Road does occasionally get flooded, making it impassable. ALL VISITORS ARE RECOMMENDED TO CHECK IN WITH THE ESCALANTE VISTORS CENTER PRIOR TO THEIR TRIP TO GET AN UPDATE ON CONDITIONS!
From Escalante drive 5 miles east to Hole in the Rock Road. Drive south on this road for 13.6 miles. Turn right onto the road signed "Collet Top" road. Travel along this road for roughly 2.4 miles to a two track road on the right hand side. If the road starts to get too rough for a 2WD vehicle, you have gone too far! Park at the register box at the beginning of the two track road.
From the parking area take the path to the north toward the smooth grey rocks. Make your way to the top of the grey rocks and start looking for tracks. If you walk to to the east, the concentration of tracks increases.
Tips for visiting this site:
- There is no water available at this site. Please bring your own water. Heat related injuries and dehydration could be a problem, espeically during the summer months.
- Cedar gnats can be bad in the late spring/early summer.
- There are some steep sections on slickrock. Sturdy hiking boots are recommended.
- The map for this area is the USGS 7.5 minute quad, Seep Flat.
HELP PROTECT THIS SITE FOR RESEARCH AND FUTURE VISITORS!
Please do not:
- sweep the sand off of the tracks
- make rubbings or casts with plaster, rubber, etc.
- carve on, paint, or otherwise deface or alter the tracks
- collect the tracks or other mineral or paleontological objects
Contact Information: For more information about this locality, please contact the Escalante Visitors Center, 755 W. Main Escalante, UT, 84726. Phone: 435-826-5499; Summer Hours: 7:30 AM - 5:30 PM, 7 days a week, mid-March - mid-November. Winter Hours: 8:00 AM - 4:30 PM, mid-November - mid-March.