Dinosaur tracks on a desert shore
On a warm summer evening in southern Utah, paleontologist Martin Lockley is doing what he does best — searching the desert for fossil footprints.
Tracking dinosaurs in Glen CanyonHOME BASE
Denver, ColoradoHE SAYS
people go to Lake Powell to eat, drink and be merry, but we go to
sweat, toil and bust our knees on the rocks."
Hugging a huge sandstone boulder, he points out dozens of raised dinosaur tracks, which decorate the ruddy rock like icing on a cake. "These are very nicely preserved," he says. "On a scale of one to 10, these are a nine or a 10."
Even as Lockley identifies the marks of delicate heels, knuckles, and toes from the early Jurassic, he struggles to keep his own footing: His socks are submerged in the cool waters of Lake Powell, and the reservoir is slowly rising.
Lockley, a longtime professor at the University of Colorado at Denver, is one of a handful of dinosaur-track specialists in the Western United States. He was born and raised in Wales; his father, known as the "Welsh Robinson Crusoe," wrote dozens of natural history books. (One of them, The Private Life of the Rabbit, helped inspire the classic novel Watership Down.)
The younger Lockley directed his own observational skills toward paleontology. After graduate work in England and further research in Scotland, he emigrated to the American West, where he began scouting the Four Corners for fossil tracks.
When drought began to shrink Lake Powell several years ago, Lockley realized that a track-rich layer of sandstone in the walls of Glen Canyon had been exposed. He believed that some 30 years underwater had weathered this rock — making the tracks clearer and easier to see — and also softened it, causing some boulders to split apart and expose more tracks. The reservoir, it turned out, had both hidden and revealed the canyon’s Jurassic past. To Lockley, this was a paradox worth exploring.
As a generous pulse of snowmelt began to flow into Lake Powell this spring, Lockley rounded up a donated houseboat for a last-ditch expedition. His crew of students and volunteers spent two weeks on the lake, mapping, tracing, and taking rubber molds of the countless tracks close to the waterline.
By the end of the season, the finds at Lake Powell included a rare mark left by a dragging dinosaur tail, and the second track of a squatting dinosaur found in the Western United States. Also well-represented were the palm-sized tracks of a type of dinosaur known as Anomoepus, common in the East but rare in the West. Lockley says all the tracks are useful clues to dinosaur distribution and behavior, especially valuable because bone evidence from the early Jurassic is poor in the Southwest.
The reservoir’s recent revelations are now underwater. Though Lake Powell will surely retreat again, it may not reach such extreme lows for many years. Lockley suspects that months of exposure to the air will have weakened the rock, and that its re-immersion will blur the tracks. He sees the periods of drought and abundance as part of a "natural cycle," and, like most Westerners, he is relieved by the return of wet weather. But Lake Powell has some 2,000 miles of shoreline, and Lockley was able to examine only a small fraction.
During one late-afternoon mapping expedition, as the sun released its sweaty grip on the canyon, Lockley raised a burly shotputter’s arm and tossed a rock into the green waters of the reservoir. Sploosh. "Out there," he said with just a touch of regret, "there’s a site with about 40 or 50 tracks — big, clear tracks. Now, it’s about 30 feet underwater."