SINCE THE AGE of 3, 7-year-old Marcos Salaverria of Annapolis has been a "dinosaur freak." Like many of his elementary school peers, he has wooden cutouts in his room, T-shirts depicting giant carnivores in battle, and he can "whip all those names out with no trouble at all," according to his aunt Charlene Cope.

Marcos, his parents and his aunt recently met at an unlikely spot for a Sunday outing: the Culpeper Stone Quarry, a 40-year old siltstone and shale quarry that until 1989 was known primarily as a producer of crushed rock for driveways and road surfaces.

Thanks to the civic-minded and history-conscious quarry owner, Gordon Willis (who happens to have a number of dinosaur-savvy grandchildren as well), the quarry is now known to geologists and paleontologists throughout the world as the site of an exceptionally abundant number of dinosaur footprints. With the help of Willis and the Virginia Museum of Natural History, the quarry is now open on weekends through mid-November for public tours and the chance to get downright intimate with some of the best dinosaur memories ever left behind.

Over 2,000 individual dinosaur tracks form lines that crisscross over a flat six-acre siltstone rockbed some 250 feet below the surface at the bottom of the Culpeper quarry. The long trail of tracks, with the left and right prints following each other in succession, reveal a drama in stone through the strides and movements of creatures who walked there 210 million years before.

The imagination strains to reach that far back in time, trying to recreate the large shallow lake with a muddy bottom, and the hot, arid conditions of Virginia's prehistoric days. Visitors can finger and follow for themselves the footprints that dried and hardened into rock when the lake receded. The quarry floor bears further evidence of the long-ago lake: ancient mud, cracked into hexagon-shaped rock patterns, and rippled rock surfaces, marking the edge of the gently lapping waters.

The Virginia Museum of Natural History provides hard hats, tour guides, brochures and a bus to take visitors from the quarry parking lot down an impressive, steep drive to the quarry bottom. "It was neat," an inspired Marcos said after his hour-long tour.

With permission from the quarry and sustained public interest, additional tours next spring are likely, according to museum spokesperson Gail Gregory.

Willis says he plans to leave several acres intact permanently, and hopes that excavation at other levels in the quarry will reveal even more fossilized footprints. Fourteen years ago, tracks were found at levels 100 feet higher.

Museum paleontologist Nicholas Fraser and other scientists suspect a dinosaur akin to the Triassic theropod Coelophysis is responsible for leaving the Culpeper tracks. Among the earliest of the dinosaurs, they belong to a species that has also been well-represented by fossil deposits in East Africa and in Wales. Despite the distance between those sites today, 210 million years ago the continents were united as one super-continent, according to quarry tour guide Anne Kuebler, a graduate student in environmental science at the University of Virginia. She explained how the land masses now in this region were then located much closer to the equator, helping to account for the hot and dry conditions.

Although the majority of the Culpeper tracks are believed to be those of Coelophysis, footprints (actually scrape marks) can also be identified as coming from two other large vertebrates: phytosaurs and aetosaurs, crocodile-like reptiles who lived around the shallow lake.

By measuring the size of the tracks and the distances between prints, scientists have been able to estimate the size, stride, weight and speed of the Virginia dinosaurs. Their calculations put the average Coelophysis at about eight to 12 feet in length, including a long, counter-balancing tail, and 130 pounds in weight. Coelophysis was a meat-eater that walked upright. The long, single sets of tracks bear out the behavior of a solitary scavenger, a dinosaur most likely to travel alone. Walking or jogging, Coelophysis was probably capable of moving at nine to 10 miles an hour. Though it had five toes, only the three front ones pressed against the ground as it moved.

For all the geological good luck that resulted in the perfect conditions for preserving tracks, an equal amount of good fortune prevailed in bringing these to light last year.

Willis is "a remarkably cooperative human being," says Tanya Furman, director of the museum's Charlottesville branch. "What he has done {by opening his working quarry to scientists and the public} is a really generous gesture."

Quarry owners typically instruct their workers to grind up any indication of fossils as quickly as possible to keep outside parties from stopping or delaying the mining process, she said.

Not only is Willis opening the quarry on the weekends, but since the tracks were exposed in 1989, he has avoided working that large section of the quarry. Willis was praised for his actions by Virginia Gov. L. Douglas Wilder in March when the governor accepted a number of excavated tracks from the Culpeper Stone Quarry.

DINOSAUR TRACKS -- The Culpeper Stone Quarry is located four miles east of U.S. Route 29 in Culpeper, Va., about a 1 1/2-hour drive from Washington. Some slots are still available for the tours offered this weekend and next, beginning at 10 on Saturdays and 11 on Sundays, four times each day. The charge is $5 per person; for safety reasons, children under six are not permitted in the quarry. Reservations are required; call 804/982-2780 between 1 and 4 weekdays. For more information, write the Virginia Museum of Natural History, UVA Branch, Clark Hall, University of Virginia, Charlottesville, VA 22903.

Charlottesville writer Jeanne Nicholson Siler is being educated about dinosaurs by her children.