In the heart of Rock Creek Park, amid picnickers, joggers and whizzing cars, Paul Inashima and a team of archeologists are looking for evidence of past civilizations.

So far, they have found quartz slivers, lots of garbage, some broken glass and a golf ball.

But they aren't disappointed, they say. The project was started not because the archeologists think anything is there, but as a precaution, to make sure nothing of historical value is buried or destroyed by planned anti-erosion construction work. Rock Creek being Rock Creek, and not Olduvai Gorge, Inashima and his colleagues are not sanguine about finding priceless artifacts.

" 'Artifacts' right now mean garbage," said 24-year-old Dennis Naglich, sitting on the sandy floor of Test Square 13, 4 1/2 feet--six layers of dirt--below the surface of the ground.

On a sunny afternoon last week, Naglich and Donald Thieme, 23, had just reached sterile soil, the point where they could be reasonably sure no artifacts will be found in this square. While Naglich fended off gnats and measured the walls of the perfectly square, sharp-edged pit, Thieme scratched his blond beard with a pencil and sketched the layers and their contents--in this case, a few rocks and a large tree root.

Naglich, Thieme and Inashima work for the National Park Service's Denver Service Center, which employs archeologists, architects, civil engineers, historians and environmental planners to maintain national parks.

According to David Ballard, the Denver Service Center's architect in charge of next year's proposed $1 million anti-erosion project in Rock Creek Park, two bridge walls, a number of storm sewers and the banks of the creek need routine restoration.

Rock Creek Park, he said, acts as a watershed: After a heavy rain the creek rises, but surrounding buildings prevent the soil from absorbing the extra water as quickly as it would in a natural environment. Ballard said the park's roadways are "not in danger of imminent collapse," but still need work.

So Inashima et al. are performing what is called survey archeology. They are working along the creek from the Potomac to the Maryland line, digging test squares that are either 2 1/2 feet square by 4 1/2 feet deep, or 5 1/2 feet square by 4 1/2 feet deep, to see what, if anything, lies below the grass. They began intensively at the end of June, along Beach Drive near Pierce Mill, and will continue through the summer.

Only when something valuable is found during construction that needs to be excavated does the process become salvage archeology. Surveying is what Naglich calls "typical" archeological work. They begin by photographing the area, and then mapping out the boundaries of the test squares. Then they systematically pass the soil through a screen or sift through it with a small mason's trowel, and finally they draw a profile of the section, graphically recording the different soil layers.

"This is a pretty strange place to work," said Naglich, brushing a gnat from his eye. "Last summer I worked in North Dakota. But here in the city, there's all this traffic." Immediately before Rock Creek, Naglich and Thieme were assigned to the Moore Site in western Maryland, where the Monongahela Indians left a village and palisade. "That was a great site," Naglich said wistfully. "I filled my shirt with artifacts."

It's still possible that something is hidden in Rock Creek. Inashima said a hillside behind Beach Drive is a known Indian quarry. Also, archeological maps show other sites throughout the park, including Pierce Mill (above ground) and the foundation remains of other mills (underground).

Inashima, a 19th-century historical archeologist, said most likely they will find lithic debitage, stone material that is the by-product of making tools. It could be from proto-Indians, who dwelled there in the 1500s, or from paleo-Indians, who lived over 10,000 years ago. Naglich and Thieme have already found quartz flakes that could date from the 1500s.

"This could get pretty dull," Naglich said, with the main diversion being the passing motorists who want to know if they've found any dinosaurs.