Paleontologists are on an extensive digging expedition to uncover the body of an ancient 25-foot long whale along the cliffs of Stratford, Va. (Nikki Kahn and Nicki DeMarco/The Washington Post)

To reach the 15-million-year-old whale, the paleontologists and their entourage hiked a quarter-mile Tuesday, trudging along the slim shoreline of the Potomac River and wading into knee-deep water not far from the birthplace of Robert E. Lee.

For more than five hours, they chipped away at clay covering the bones of the ancient goliath, which likely belong to an extinct baleen whale that would have been 25 feet long. Based on the cliffs where it was discovered in Stratford, Va., the whale lived during the Miocene Epoch, five million to 23 million years ago.

“You’re seeing stuff for the first time in 15 million years. You’re seeing history be exposed,” said John Nance, paleontology collections manager at the Calvert Marine Museum in Southern Maryland and a member of the team that made news by extracting a six-foot-long, 1,000-pound whale skull from the site last month.

They have come to work here more than a dozen times since mid-June, when a staff member at Stratford Hall, the ancestral home of the Lee family, spotted the whale skull poking out of the sandy cliffs while accompanying researchers on a pollen study.

On Tuesday, the group used pickaxes, shovels, screwdrivers, putty chisels, paper towels and plaster to find and then preserve the whale’s ribs, vertebrae, tailbones and a possibly a scapula. They will return Saturday, and possibly a few more times, to dig the bones out and take them to the Calvert museum, where they plan to reassemble as much of the skeleton as possible.

The dig resembled a scene from an Indiana Jones movie. And the excitement was palpable. While shark teeth and dolphin fossils have been discovered in the area, the whale is the largest creature they’ve uncovered.

Kate Kistler, a 21-year-old rising senior at Harrisburg University in Pennsylvania and an aspiring paleontologist, said it was fascinating to see an organism that lived millions of years ago uncovered in the cliffs.

“And I get to hold a piece of it,” she said.

She and the others worked quietly, the pounding of the pickax into soft clay, shrieks of birds overhead and the river lapping at the beach breaking up the work between media interviews.

Donald Morgan, a 22-year-old rising senior at Towson University, and Jess Howard, a 20-year-old rising senior at the University of Maryland College Park, are two of Calvert’s summer interns.

Morgan hopes to be a paleontologist; Howard plans to study marine biology.

Neither expected to be working with whale bones, particularly the skull.

“I wasn’t expecting to be able to work on anything this large,” Morgan said. “Just seeing this animal almost come to life was pretty cool.”

He was obsessed with dinosaurs as a child and called this experience “finally getting to live the dream.”

“Anything that involves going out and digging up bones is right up my alley,” he added.

Daryl Domning, a paleontologist and human anatomy professor at Howard University, has been on numerous digs throughout the world. He wears a brimmed hat adorned with pins of countries — including Libya, Venezuela, Austria and France — that he has visited for his work on sea cows.

He was joined on this excavation by his 19-year-old daughter, Charlotte. Working together for the first time — Charlotte wants to be a horse veterinarian — they uncovered a nearly complete vertebra and several tailbones.

“Here, almost any time, you can find whole new kinds of animals that nobody has found before,” Domning said.

For Stephen Godfrey, the Calvert Museum’s curator of paleontology, the fossils tell a story.

“It’s like forensic paleontology,” he said. “We don’t know yet what story this whale skull is going to tell us.”

But the location of the bones does give away some secrets. The fossils were found close together but not laid out head to tail. That means scavengers likely dined on the carcass and moved the bones around.

The blue-gray clay surrounding the fossils also indicates that the whale was at the bottom of the ocean when it died, rather than beached along the banks of what eventually became the Potomac River.

Rob Furey, a professor of integrated sciences at Harrisburg, brought four students and his 14-year-old daughter to the site for a field-studies class.

“These are the kinds of things that underscore evolution,” he said.

The group uncovered several clumps of fossils but was only able to cut one chunk out to take back to the Calvert museum.

They coated the others with wet paper towels and then strips of burlap dipped in plaster to create what’s called a field jacket, mimicking the protection a cast affords a broken arm or leg.

“We’ve got a broken bone,” Godfrey said. “We’re putting on a cast.”

As Domning and Godfrey poured leftover plaster on top of the casts to make a final layer before reburying the fossils in clay until Saturday, the others rinsed off their hands and tools in the river.

Then Domning ticked off the reasons why people decide to become paleontologists: to play in the mud, mold casts with plaster and dig holes in the ground.

“This is the old-school way of doing it,” he laughed.