Dinosaur National Monument: Earl Douglass and the Carnegie Quarry

Dinosaur National Monument protects the site where the palaeontologist Earl Douglass, working for Andrew Carnegie’s museum in Pittsburgh, found a rich bed of Jurassic dinosaur skeletons in August 1909. The excavation, known as the Carnegie Quarry, supplied museums with dozens of skeletons, and in 1915 President Woodrow Wilson declared the site a national monument. Today its famous “Wall of Bones” lets visitors see fossils still embedded in the rock.

Background: Carnegie’s search for dinosaurs

After the success of Dippy the Diplodocus, the Carnegie Museum in Pittsburgh wanted more large dinosaurs for its halls. Its director, William Jacob Holland, sent collectors to the Late Jurassic Morrison Formation, the rock layer that had produced so many famous finds during the Bone Wars.

Earl Douglass (1862–1931), a geologist and experienced fossil collector from Minnesota, began searching the Uinta Basin of north-eastern Utah in 1908. The rocks there had been tilted steeply by mountain building, bringing Jurassic layers to the surface in long ridges.

The discovery of August 1909

On 17 August 1909, after weeks of fruitless searching near the Green River, Douglass found a series of tail vertebrae of a large sauropod lying in their natural order in a sandstone ledge. He recorded the moment with delight in his diary, recognising that articulated bones suggested a complete skeleton lay inside the hill.

The skeleton proved to be an Apatosaurus, later described as Apatosaurus louisae and named after Andrew Carnegie’s wife, Louise. It became one of the centrepieces of the Carnegie Museum’s dinosaur hall.

Douglass soon realised that the sandstone held far more than one animal. The layer had been the bed of an ancient river, where floodwaters had swept carcasses together and buried them in sand and gravel about 150 million years ago.

The Carnegie Quarry

Douglass and his crews worked the site from 1909 to 1922, quarrying into the tilted rock with hand tools, picks and occasional explosives. Douglass moved his family to the area and built a homestead nearby. Bones were jacketed in plaster and hauled by wagon to the railway for the long journey to Pittsburgh.

The quarry yielded thousands of bones from many individuals. Finds included Allosaurus, Apatosaurus, Barosaurus, Camarasaurus, Diplodocus and Stegosaurus, as well as smaller plant-eaters such as Dryosaurus and Camptosaurus. One of the most celebrated specimens is an almost complete juvenile Camarasaurus, now displayed in Pittsburgh in the position in which it was buried.

After Carnegie’s death in 1919, the museum wound down the work. The Smithsonian Institution and the University of Utah carried out further excavations in the early 1920s.

A national monument

To protect the quarry from mining claims, the federal government acted under the Antiquities Act. On 4 October 1915 President Woodrow Wilson proclaimed Dinosaur National Monument, then covering just 80 acres around the quarry.

In 1938 President Franklin D. Roosevelt expanded the monument to more than 200,000 acres, taking in the spectacular canyons of the Green and Yampa rivers in Utah and Colorado. In the 1950s a proposed dam at Echo Park, inside the monument, became a national conservation battle; the plan was dropped in 1956, a landmark moment for the American environmental movement.

Douglass had dreamed of leaving bones in place for the public to see. That vision was realised when a visitor centre was built over the quarry face and opened in 1958, with about 1,500 bones exposed in relief on the tilted rock. Structural problems closed the building in 2006, and a rebuilt Quarry Exhibit Hall opened in 2011.

The Jurassic world of the quarry

About 150 million years ago this part of Utah was a broad, seasonally dry plain crossed by rivers flowing from distant highlands. Conifers, ferns, cycads and ginkgoes grew along the waterways, while long-necked sauropods browsed and predators such as Allosaurus hunted.

Many of the animals at the quarry probably died during droughts, when they crowded near shrinking water sources. When the rains returned, floods carried their remains downstream and dumped them on a sandbar in the river channel. Over time the bones were buried, mineralised and later tilted almost upright when the Rocky Mountain region was uplifted.

Besides dinosaurs, the rock preserves crocodile relatives, turtles, small mammals and freshwater clams. Together they give a snapshot of a Late Jurassic ecosystem very similar to those recorded elsewhere in the Morrison Formation, from Colorado to Wyoming.

By the numbers

Timeline

• 1908: Earl Douglass begins searching the Uinta Basin for the Carnegie Museum.
• 1909, 17 August: Douglass finds articulated sauropod tail vertebrae.
• 1909–1922: The Carnegie Quarry is excavated for the Carnegie Museum.
• 1915, 4 October: Woodrow Wilson proclaims Dinosaur National Monument.
• 1938: Franklin D. Roosevelt greatly enlarges the monument.
• 1956: The Echo Park dam plan is abandoned.
• 1958: The quarry visitor centre opens over the Wall of Bones.
• 2011: The rebuilt Quarry Exhibit Hall reopens.

Why it matters

The Carnegie Quarry is one of the richest Jurassic dinosaur sites in the world and filled museum halls with skeletons still on display. Its preservation in place turned it into a rare outdoor laboratory where the public can see how fossils actually lie in rock. The monument’s later growth and the Echo Park controversy also made it a milestone in the history of American conservation.