Wednesday, August 8, 2007
Next time you walk along a sandy beach, look down. You might be walking over fossils millions of years old.
Fossils are hardened remains, imprints or traces of plant and animal life that existed in earlier geological periods. They have stories to tell -- not with a voice, but in the clues they give us about what life, weather and Earth's environment were like long ago.
Did you know that before there was a Chesapeake Bay, the region was covered by a warm, shallow sea that offered lots of nutrients and plants for marine life? Sharks, rays and whales lived and died in the area of today's Potomac River and Chesapeake Bay.
As the sea's waters receded, fish, birds and other animals became embedded in what are now cliffs lining the shore. Their soft tissue -- muscles and blood vessels, for example -- deteriorated, but hard parts including teeth and bones remain.
The most common fossils found locally are sharks' teeth. However, it's not unusual to find crocodile teeth, whale bones and dental plates of rays.
Look carefully as you walk in the sand at Breezy Point, Flag Ponds and Calvert Cliffs in Maryland and Westmoreland State Park in Virginia. Fossilized shark teeth from 12 million to 22 million years ago are right under your toes.
In some places, you might brush sand away from buried shells to uncover an ecphora, the shell of a snail that lived 5 million to 12 million years ago. One species, the double-named Ecphora gardnerae gardnerae, is the Maryland state fossil.
And what at first glance appears to be an ordinary scallop shell might be Virginia's state fossil, the Chesapecten jeffersonius, dating back about 5 million years.
Lauck Ward became fascinated with fossils when he was 8. His family often vacationed in the Shenandoah Valley, where an 80-year-old resident took Ward, his brother and some friends on hikes, stopping often to point out signs of the past.
Ward learned about trilobites -- extinct marine arthropods about 450 million years old that were the ancestors of many of today's insects. The fossils he found were embedded in shale, a thinly layered rock.
These were life-changing outings for Ward. "It's like an idea that clicks in your head, then gets you seeking more information," he said. Now, 50 years later, he is the chief paleontologist -- a person who studies fossils -- at the Virginia Museum of Natural History in Martinsville.
Any kid can have fun fossil-hunting.
While 11-year-old Rose Hancock of St. Mary's County was collecting sharks' teeth near the water's edge at Breezy Point recently, others were having just as much luck yards away, in the dry sand.
Kayla Hymiller, 6, of Carroll County found a three-pointed cow-shark tooth while running her hand along the sand near a piece of driftwood. "It was sitting right there," she said happily.
--Ann Cameron Siegal