Each year, more than 4 Million people visit the Smithsonian’s Natural History Museum to discover the wonders of the natural world and “collect fossils” from the gift shop. A far smaller group find their way to the Calvert Cliffs, where — if you have better eyes than mine — you can find shark’s teeth along the broad waters of the Chesapeake Bay.
Still fewer (that rarest of fossil enthusiasts) know about Purse-Nanjemoy, where shark’s teeth and other fossils can be found in abundance along the banks of the Potomac. Whereas the Calvery Cliffs features plentiful parking but has been mostly picked clean, Purse-Nanjemoy has a tiny, hidden parking lot along the side of a busy two-lane highway and is teeming with fossils.
What to bring: You don’t need to bring anything as these fossils are all loose along the shoreline, but you’ll feel more like a seasoned naturalist if you bring a small pickax and a handlebar mustache. I highly recommend a fossil sifting screen or, if you don’t have one, a kitchen colander like you’d use to drain pasta. It’s also a good idea to pull out your Wellies (or some other knee-high water boot) so that you can wade into the river.
To get there: Follow the Riverside Road south to GPS coordinates 38.433 N, 77.256 W. If you come early on a weekday (and very early on a weekend), you’ll find an empty space in the small lot on the left side of the road. Cross the road to the trailhead that leads down to the river (a short quarter-mile hike). I also recommend you time your visit for low tide on the Potomac, as much of the shoreline is submerged at high-tide.
Tips for finding fossils: At first we saw nothing, and probably burned close to half an hour sifting fruitlessly through rocks on the shoreline. Once we saw them, they were impossible to miss. Shark’s teeth and other fossils show up as dark specks in the tan sand. Although they are everywhere, you need to train your brain on an easier spot. Start by searching for a patch of open sand just beyond the waterline (fossils are harder to find on land or amongst the rockier parts of the river bottom). Seek out a black speck in the sand. Sharks teeth have a distinctive shape (see picture above of some teeth we found on our first trip to Purse). But don’t pass up the rarer late Paleocine fossils. If it’s dark black and shiny, it’s most likely a fossil from the Aquia Formation (55-59 million years old).