Mill Canyon Dinosaur Tracks
The Mill Canyon Dinosaur Trail is a bold experiment; there are no guards or fences here. You, the visitor, are the protector of this valuable resource. It is illegal to remove, deface, or destroy improvements, rocks, and fossils.
The dry climate and eroded landscape of today is very different from the environment that existed when dinosaurs roamed southern Utah. Climates were mild and moist during the Jurassic period 150 million years ago. The fossil remains of plants and numerous dinosaurs are typically found in the Morrison Formation. The Morrison Formation is a complex series of clays, shales, and sandstones that settled in swamps, bogs, shallow lakes, and the broad and often slow moving streams that wandered over a low-lying featureless landscape. Cycads, ginkgoes, and conifers formed forests, shading an undergrowth comprised largely of ferns. Horsetails and succulent plants grew abundantly in swamps and bogs. The Morrison Formation contains the fossil remains of plants and numerous kinds of dinosaurs including: Allosaurus, Camptosaurus, Stegosaurus, and Camarasaurus.
Jurassic rocks are exposed over wide areas in eastern and southern Utah. Their multicolored layers provide a scenic wonderland. Water deposited and wind blown sands and silts comprise these formations. They include the Navajo sandstone which overlays the late Triassic Kayenta and Wingate sandstones, and the Entrada sandstone that is seen in the majestic formations of Arches National Park.
There is a self-guided walking tour in the area. Pamphlets which describe the tour sites can be picked up at the Grand Resource Area (address below). Highlights of Jurassic dinosaurs include fossilized bones of all shapes and sizes, fragments of fossil wood, and tracks.
To reach the Mill Canyon Dinosaur Trailhead, drive 15 miles north of Moab on U.S. 191, then turn left at an intersection just north of highway mile marker 141. Cross the railroad tracks and continue 2 miles on a bladed dirt road to the Dinosaur Trailhead. The road is impassable when wet.
Remnants of an old copper mill can be seen on the south side of the canyon. Copper ores (azurite and malachite), exposed along the Moab fault, were mined and processed here in the late 1800's. Limited quantities of ore and fluctuating prices probably made the venture economically unfeasible and the mill was abandoned.
An essential requirement for the formation of a fossil is rapid burial by sediment after the organism dies and the soft tissue rots away, leaving the bony skeleton. This burial normally occurs in rivers, lakes, or the sea into which the carcasses of land-living animals may be washed. Two processes may then occur: (1) permineralization, where organic matter in the bones may decay and be replaced by minerals from water percolating through the sedimentary rocks; or (2) petrifaction, the bony structure may be replaced entirely by minerals. Alternatively, the bones may dissolve, leaving a hollow mold that may be filled by minerals that form a solid replica of the bone, a natural cast. Land movement and erosion may then lead to exposure of the fossil.
Allosaurus was a large, bipedal, saurischian (lizard-hipped), meat-eating dinosaur. Heavily built, Allosaurus had powerful hind legs, relatively short but strong forelimbs, and a very large head. A massive tail must have aided in balance. The animal grew to a length of nearly 39 feet. The huge jaws were lined with large serrated, stabbing, and cutting teeth. Both hands and feet were equipped with large claws.
Stegosaurus was a moderately large four-footed, ornithischian (bird-hipped), plant eating dinosaur, which is characterized by a double row of large, alternately spaced plates that ran down its back and large spikes at the end of its tail. The animal grew to a length of 25 feet and may have weighed 1.5 tons. Stegosaurus had an extraordinarily small brain, which weighed no more than 2.5 to 2.8 ounces.
Camarasaurus was a very large, heavy bodied, four-footed saurischian (lizard-hipped), plant-eating dinosaur. It had a short skull with a blunt snout and a fairly long neck and tail. Camarasaurus grew to a length of 59 feet and the four pillar-like legs may have supported a weight of nearly 20 tons.
Camptosaurus was a moderately sized, ornithischian (bird-hipped), plant eating dinosaur, which was presumably quite nimble and fast, but otherwise quite defenseless. The animal grew to a length of around 20 feet. Hoof-like claws on both fingers and toes suggest that it often walked on all fours.
The remains of the Halfway Stage Station are located east of the Dinosaur Trail. The Halfway Stage Station served the traveling public between Moab and the railroad at Thompson. The first passenger train went through Thompson to Salt Lake in April of 1883. The railroad was 35 miles from Moab. The trip from Moab to the train took eight hours for passengers, so travelers stopped at the station for lunch. Slower freighters spent the night on a two day trip. To reach the stage station proceed north toward Highway 191. At the first intersection turn right and proceed to a dry wash. Turn right on the jeep trail at the wash crossing and continue to the Stage Station.
Moab Field Office
82 East Dogwood
Moab, Utah 84532
(435) 259-2100