Dinosaur tracks on a desert shore
by Michelle Nijhuis
On a warm summer evening in southern Utah, paleontologist Martin Lockley is doing what he does best — searching the desert for fossil footprints.
NAME
Martin Lockley
Paleontologist
KNOWN FORTracking dinosaurs in Glen Canyon
HOME BASEDenver, Colorado
HE SAYS "Some
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."