When Andre Delgalvis found the first dinosaur track a couple of years ago, he was mildly impressed.

Today he's astounded.

He's now discovered thousands of tracks in dozens of locations along the receding shoreline of Lake Powell.

"I couldn't believe how many tracks I was finding," he said, peering over a slab of Navajo sandstone peppered with the footprints of Jurassic Age dinosaurs and crocodiles. "Tracks are appearing that possibly no one's ever seen before."

Delgalvis, of Grand Junction, Colo., is a professional photographer who specializes in moody, color-rich portraits of Lake Powell. Now he's part of a team organizing an extraordinary rescue effort for what one scientist calls an "amazing" discovery — to rescue the rich lode of dinosaur tracks before Lake Powell rises up and swallows them again, perhaps forever.

In recent weeks, Delgalvis' discoveries have caught the attention of professor Martin Lockley, a geologist and dinosaur track expert with the University of Colorado in Denver.

"Yes," Lockley said, "we've definitely found some new stuff here."

Lockley previously documented dinosaur tracks in about three dozen locations near Lake Powell. With Delgalvis' help, there are now about 80 documented sites with tracks — most of which had been submerged for 30 years.

Lockley said that although the water kept the tracks inaccessible, it actually enhanced many of the footprints. "It's brought out the subtle relief, if you like, more clearly."

For better pictures, Lockley himself sometimes enhances the footprints by filling them in with loose red dirt to better define their shape for the camera. But even without such tricks, many of the tracks are astonishingly vivid. Pointing to an 8-inch track left by a meat-eating raptor 200 million years ago, Delgalvis said, "You can see the claws. And you can actually see the digits, the knuckles."

A quarter-mile away across the lake, Lockley pointed to a pair of footprints several feet apart, with a long groove stretching between them.

"That's where a dinosaur dragged his tail," Lockley said. The impressions were preserved after the mud in which they were initially made hardened into sandstone.

A few steps away, four large tracks make up what dinosaur experts call a "trackway." All four prints were evidently made by a single dinosaur, walking in a northeasterly direction 200 million years ago. Lockley believes the four footprints were left by a carnivore known as dilophosaurus, the same species portrayed on the T-shirt he was wearing.

The dinosaur was probably 5 to 6 feet at the hip and was 15 to 18 feet long, Lockley said.