Washington - From the banks of the Potomac River, in a region steeped in American history, a massive fossil was dug up last month that apparently can be traced back to a time long before this country's recorded history, a time deep in the world's prehistory.
The fossil is the skull of a whale that is “approximately 15 million years old,” said John Nance, the paleontology collections manager at the Calvert Marine Museum in Southern Maryland.
The skull is about six-feet long and is believed to weigh about 1 000 pounds. It was excavated in July from the cliffs at the edge of the Potomac on the grounds of Stratford Hall, the home of Virginia's Lee family and the birthplace of Robert E. Lee. The Potomac River forms part of the border between Maryland and Virginia.
The rest of the skeleton, which experts believe belongs to a type of baleen whale that has since gone extinct, remains embedded in Stratford Hall's sand-coloured cliffs.
Stratford Hall is in Westmoreland County, and both George Washington and the country's fifth president, James Monroe, were born in the county, about 100 miles southeast of Washington.
The eroding river bank where the fossil was found is one of the world's few Miocene cliffs, said Jim Schepmoes, Stratford's spokesperson, referring to the geological epoch 5 million to 23 million years ago.
Thousands of shark teeth have been found there, and the area is known to be rich in marine fossils. Whales are relatively common in the area, so the rogue bone has been found in the past.
“But to have such a large and complete specimen is pretty uncommon,” Nance said. “In a marine environment, the bones are usually scavenged and scattered all about. The really interesting thing,” he said, “is we have all the post-cranial material — the vertebrae, the ribs, the flipper bones. It will give us a more complete picture of what these animals looked like.”
Schepmoes agreed that the whale “is about the biggest” fossil discovery in the cliffs because it seemed to be in one piece.
The first signs of the whale skull were discovered in June by Jon Bachman, another Stratford Hall staff member and fossil hunter, while he was walking along the beach, Schepmoes said.
Staff members of the Calvert facility had been working nearby and were brought to the site, and they began digging with hand tools such as picks and putty knives.
“The more they dug,” said Schepmoes, “the bigger this thing got.”
When the fossil emerged from the cliff face on July 20, Nance said, it was wrapped in plaster and burlap and lashed to metal poles. About a dozen people hoisted it into a boat, which took it to the nearby Westmoreland State Park boat ramp. From there, it was trucked to the marine museum.
Nance said the determination of the fossil's age was based on the geologic formation, known as the Calvert Formation, in the cliffs where the bones were found. Scientists have been studying the Calvert Formation for more than 100 years and have dated the various layers of rock, dirt and sediment. This makes it possible to determine the age of a fossil in relation to where it is discovered.
The specimen was identified as a baleen whale based on skull size and shape, and Nance noted that it belongs to a family of whales that is extinct. However, its shape and appearance would be comparable to a modern-day minke whale, he said. It is believed that the fossil belonged to a whale that would have been 25 or more feet long from nose to tail.
Scientists won't be able to conclusively determine the whale's species until the entire fossil is excavated, cleaned and examined, Nance said.
So far, only the skull, lower jaw and some isolated vertebrae and rib bones have been removed from the sand-covered cliffs overlooking the river. These bones are on display in the paleontology hall of the museum in Solomons, Md., where interns are working to clean sand and clay from around the bone, Nance said.
A team plans to continue digging for the remainder of the skeleton this week. In all, Nance expects the excavation process to take about two weeks. - The Washington Post