Prehistory along the Potomac

WE needed no submersible to take us 300 feet to the bottom of the sea nor a time machine to transport us back 14 million years. We reached both by walking through a forest and arriving at a scimitar of white-sand beach bordering the Potomac, close to where the river empties into Chesapeake Bay.

We had come to hunt for fossils, and we would not be disappointed.

Bluffs on the Virginia side of the Potomac and cliffs in Maryland along Chesapeake Bay date to the Middle Miocene Epoch, about 11.2 to 16.6 million years ago. As such they constitute one of the world’s greatest repositories of the rock-hard remains of hundreds upon thousands of kinds of prehistoric sea creatures -- giant sharks, whales, dolphins and sea cows -- as well as camels and mastodons.

During the Miocene, when much of Earth enjoyed a tropical climate, the Atlantic covered parts of Virginia and Maryland as far north as present-day Washington. The warm, shallow waters apparently served as a nursery for sea mammals and a hunting ground for sharks -- and as a graveyard for all when their lives were over.

Their remains sank to the ocean floor, where they were buried in silt and gradually turned into fossils.

Travelers who come to Virginia and Maryland to explore historic sites might also devote a day or so to investigating the area’s rich geological past. Sometimes both activities can overlap, as at Robert E. Lee’s boyhood birthplace in Stratford, Va., or the nearby Popes Creek Plantation, George Washington’s birthplace not far from Colonial Beach, Va., that’s now a national monument.

The Potomac-edged bluffs at both have yielded thousands of fossils over the years. And there is something else here to excite the imagination: magnificent bald eagles and ospreys.

My wife, Liet, and I started our fossil adventure last year at Virginia’s 1,350-acre Westmoreland State Park, about 100 miles southeast of Washington and just a few miles south of Washington’s birthplace.

We had as our guide Steve Davis, chief ranger, who says he wouldn’t trade his job for any other. In the exhibit area out front, Davis keeps an open box filled with small fossils that he regularly replenishes. He lets children choose one or two to take home.

In an adjacent glass case is a display they love: About 22,000 ancient shark teeth are strewn across an entire shelf. That’s how many a single shark could produce and shed in a lifetime. Now, as in the Miocene Epoch, sharks continue to grow rows of replaceable teeth. When one tooth drops out, another moves forward and takes its place.

Because shark skeletons consist of cartilage instead of bone, they quickly deteriorate after the fish die.

The teeth, composed of one the hardest organic materials known and hence resistant to decay, are usually all that remain.

The best time to look for fossils, Davis told us, is between tides, especially after storms. At the beach, Davis pointed to twin bluffs, 150 to 250 feet high and topped with trees. “That’s millions of years right there,” he said of the clearly demarcated layers of silt, sand, clay and gravel visible on their weathered faces.

It is from just such a matrix that fossils wash out during heavy rain, are tossed about and cleaned by the water, then swept back to shore by waves that, in some spots, undercut the bluffs and cliffs.

Heads down, we searched the sandy strip between the two bluffs for some evidence of prehistoric life. Davis soon spotted in the shell-ridden detritus a shark’s tooth and the dental plate of a long-extinct plankton-eating ray, a narrow piece of dark material about 1 1/2 inches long and less than half an inch wide. The plate was marked by a double row of parallel grooves, tiny channels through which the ray filtered its microscopic food.

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To more recent times

BEFORE we headed for Maryland, we decided to visit Washington’s birthplace, on the northern side of the park, and the ancestral home of Robert E. Lee, on the southern. We stayed the night at the Cheek, a modern, 15-room guesthouse on the 1,600-acre Lee plantation.

Built on the lip of a wooded ravine, it gave us the illusion of being in a treehouse, particularly the next morning in the adjacent screened dining room, where we could look right into the branches and listen to the birds while we ate warm, homemade biscuits and corn bread for breakfast.

The handsome red-brick Lee mansion, dating from the 1730s, has two wings, a grand staircase leading to the central part and four chimneys astride each corner of the roof. The high-ceilinged, paneled Great Hall looks out on a splendid view of an undulating lawn that seems to hop, skip and jump to the silver-gray ribbon of the Potomac.

In contrast to Lee’s birthplace, Washington’s must have been a humble one. The footprint of the long-vanished house, as outlined in crushed oyster shells by the archeologists who excavated it, suggests a small structure that probably did not contain the kind of fine furnishings used to convey the genteel 18th century atmosphere in the 1930s “reconstruction,” which was built, it turned out, on the wrong foundation.

Because the Washingtons were tobacco farmers, the National Park Service tries to demonstrate what agriculture was like in the 18th century when split-rail fences served to keep animals out of the fields rather than in. The breeds seen roaming the grounds are authentic to the period. The pigs and sheep were thought to be extinct until several were found running wild on two islands, one called Hog Island, off Virginia, the other called Ossabaw Island, off Georgia. These became the stock from which the present animals stem.

I wondered whether any of the Washingtons had wandered down to the plantation’s beach to look for the odd “stones” that lay on the sands after storms. Before dates were assigned to such relics, the family could not have known how old they were and probably paid them no heed.

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The giant shark

FROM Virginia, we crossed over the Patuxent River Bridge into Maryland and drove south to Solomons, a thin finger of an island and a favorite with boaters and Washington day-trippers. The island, separated from the mainland by a strip of water, is only 60 miles from the nation’s capital, but it feels a world away.

We were taken with the lovely white houses lining its streets, many of them Victorians. Our bed-and-breakfast, the Back Creek Inn, was one such place. Its pretty garden runs right to the water’s edge.

We had come to Solomons with a purpose: to go to the Calvert Marine Museum, which houses an outstanding collection of fossils from the Patuxent River and the Calvert Cliffs on Chesapeake Bay. These have been mounted in lively displays, and the overflow is kept in cabinets with glass-topped drawers that the public is free to pull out and examine.

Stephen Godfrey, the curator of paleontology and an amiable host whose enthusiasm was contagious, showed us around. He and the museum staff make children feel particularly welcome. At the large Discovery Center, young visitors are encouraged to search through a sandbox, thick with mollusk shells, for a fossil they can keep. Naturally, shark teeth are the prime prize.

But what really turns them on hangs from the ceiling of another room: a life-size reconstruction of a giant white shark (which in the Miocene might have weighed up to 50 tons and stretched 50 feet in length). Its mouth agape, with all its long, sharp teeth gleaming in the dim light, it is a monster out of a nightmare.

Godfrey invited us to come have a look at his newly opened exhibit. Filling a long display case were the 8-million-year-old fossilized skull and neck vertebrae of a whale. They had been partly exposed by Hurricane Isabel in 2003 along the St. Mary’s River.

With our interest in marine fossils now more piqued, Liet and I headed a few miles north to Flag Pond Nature Park to see whether we could find something bigger than the small shark tooth and ray dental plate from Westmoreland State Park.

Flag’s broad beach is partly wrapped around a cove, with a long sandbar jutting out from shore. A ranger told us we would probably find the best fossils on the other side of the bar.

When we got there, we realized we lacked the patience to sift through the piles of broken shells and other fragments lining the shore. But we did find something, to our surprise: a living fossil. Three of them, in fact.

They were horseshoe crabs in the act of mating, with their armor-clad bodies and long, pointed tails half-submerged in the water. Their kind has been on Earth for 350 million years -- and here these were, only moderately modified in appearance from their ancestors, still perpetuating themselves, when most of the creatures with which they have shared the sea through time have become extinct or evolved new shapes and behaviors. What better way to remind us that even ancient history can speak to modern-day life?

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Beaches to comb

GETTING THERE:

From LAX, fly into any of three airports in the Washington area. The least expensive fare is into Baltimore-Washington International; nonstop service is offered on Southwest and United, direct service (stop, no change of plane) is available on American, Delta and Southwest, and connecting service (change of plane) is available on AirTran, Continental, America West, American, Delta, Frontier and US Airways; restricted round-trip fares begin at $306. Nonstop service to Washington Dulles is offered on American and United; connecting service is available on Delta, AirTran, Continental and America West. Into Reagan National, nonstop service is offered on Alaska, and connecting service is available on America West, United, Delta, Continental and American. Restricted round-trip fares to Dulles or National begin at $338.

WHERE TO STAY:

Stratford Hall Plantation, 483 Great House Road, Stratford, VA 22558-0001; (804) 493-8038, www.stratfordhall.org. Two guest houses, with a total of 20 rooms. The serenity springs from location among ancient trees. Doubles from $105.

Back Creek Inn Bed & Breakfast, 210 Alexander Lane, Solomons, MD 20688; (410) 326-2022, backcreekinnbnb.com. Comfy, charming and close by the water. Doubles begin at $110, including full breakfast.

WHERE TO EAT:

CD Cafe, 14350 Solomons Island Road, Solomons, Md.; (410) 326-3877. Contemporary American cooking emphasizing locally fresh products. The key lime pie topped with raspberry sauce was memorable. Entrees $9-$25.

HUNTING FOSSILS:

Westmoreland State Park, State Park Road (off Route 3); (804) 493-8821, www.state.va.us/dcr/parks/westmore.htm. Park has weekly scheduled fossil hikes. Camping cabins and campsites, pool. Admission $3 a vehicle, $4 on weekends.

George Washington Birthplace National Monument, 1732 Pope Creeks Road (off Route 3); (804) 224-1732, www.nps.gov/gewa. Admission: $4 adults, children under 16 free.

Stratford Hall Plantation (see above). Admission $7 adults, $3 children.

Flag Pond Nature Park (off Route 4, 10 miles north of Solomons); (410) 586-1477, www.calvertparks.org. Scheduled tours. Admission $6 a vehicle.

Calvert Marine Museum, Solomons, Md. (off Route 4); (410) 326-2042, www.calvertmarinemuseum.com. Focuses on paleontology, estuarine biology and local maritime history. Admission $7 adults, $2 children ages 5-12.

-- Dale M. Brown