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The put-in is at Timís II Crabhouse, a restaurant and local watering hole with lots of water views. The border with Maryland used to lie a short distance offshore, which is why Timís and its predecessor restaurant sat on piers on the river. Provided you suspend disbelief in shoreline migration over the last 300 years, when youíre in the restaurant you can pretend youíre in Maryland where people are presumably allowed to be naughtier.
I put in at mid-morning on the beach on a cloudy day with an expected high in the low 50ís. Wind was 10 mph out of the NE across a long fetch. The waves were tolerable, but they stirred up enough sediment to limit the water visibility to 3Ē-6Ē. Tides still play a role here, but in contrast to Westmoreland State Park further downstream, the water here was virtually fresh.
On a dropping tide, I headed upriver hugging the shallows. Massive blocks of crumbly greenish sandstone packed with 3-4Ē long snail fossils form natural rip-rap. Before the day was over, I saw these same snails preserved many different ways. In this location, the dead snails filled with the sand which later hardened. When the shells dissolved away, they left body casts. Although some casts can be wiggled and unscrewed from the blocks, they tend to fall part and the result isnít very attractive anyway. The best souvenir from the sandstone blocks is a photograph.
It had rained heavily recently, and one low, brown cliff had liquefied and flowed onto the beach. It was a mixture of sand and clay that allowed one to walk across it in well drained areas if you moved quickly. However, when I approached the cliff to examine what turned out to be just a tree root, one leg sank into the mud up to my knee. While I mulled over whether pulling my leg out would cost me the boot, my other leg sank in as deeply. To get out, I had to sit down, pull my feet out one by one, tug on a stuck boot until it came out, then scoot to firmer ground. Being dressed in a wetsuit meant I could at least rinse off some of the mud in the cold river water.
I passed a little creek, fronted by its own sandbar, with a powerful outgoing tidal current. You canít miss it: thereís a derelict barge washed up on the nearby beach. Itís fed by Passapatanzy and Dry Bridge Creeks, and might make an interesting short trip starting just before high tide. Aerial photos show that Passapatanzy creek reaches swamps in about 1 mile. Topo maps suggest these little creeks sliced through the hills like knives during the last ice age and now drain a big chunk of King George County.
There were a few large homes along these shores. At least, I think they were homes. They were built very sturdy, as if the owners actually understood what it means to leave something expensive on the shores of a large river with a northeast exposure. But they were so homely, itís also possible they were institutions of some kind.
The further upriver you go toward Potomac Creek, generally speaking, silicified versions of the snail shells become easier to find. They are so tough they can withstand significant pounding, and piles of the snails lie in the surf. These snails must have been very common when they were alive.
Bull Bluff is simply amazing. Except for a tough layer of sandstone about 20 feet above river level, the high cliffs are all sand, clay, and snail shells. As the cliffs erode, those shells are released, the tough ones concentrating on the beach. Blocks of fallen sandstone containing the usual snail casts form a reef at the base of the cliffs. There are a few giant winged oyster shells here too, along with the occasional fossil turtle and bird bones. I found Bull Bluff to be as breathtaking in its own way as the most fossiliferous beaches of York River State Park or Chippokes Plantation State Park. But it is unique in that it is much older. Unfortunately, this area is relatively close to DC, so when the eagle lookout at the top of the cliff is eventually replaced with a mansion, the shoreline will be bulkheaded and a unique part of Virginia natural history will effectively be lost.
I had been headed for Marlboro Point, which reputedly was a spot to look for sharkís teeth. But it had been bulkheaded. So I turned into the wide mouth of Potomac Creek. Thereís a small marina on the south bank, but the water was so shallow at low tide that my paddle was striking the bottom hundreds of yards from shore.
This was one month after my trip to Westmoreland State Park which lies about 30 miles downriver. The pendulum of the seasons was clearly swinging despite the cool air temperature. The water was a little warmer, there was a lot more fish activity, and the ospreys were back from their tropical vacations.
As I picked my way down the east bank, a cruising osprey snatched at the top of a tall tree, and broke off a 7í long, skinny branch. The oversize branch then dragged him half way to the ground before he reluctantly let it go. I didnít think this reflected on his inexperience at the time; stick-breaking is not an exact science. He circled, hit the top of the tree again, broke off a stick only 6Ē long, and headed back to the nest with his prize. At that point it was clear it wasnít just bad luck; no experienced creature would let his spouse see him return to the nest with a stick the size of a large pencil. As osprey populations increase and they pluck the dead tree tops bare, I wonder if theyíll begin to gather more nesting materials from the ground.
Crossing over to the other side, the few low hills appeared to be covered with uninteresting sediments. But closer examination showed that underlying those sediments, almost at sea level, was a few feet of exposed Aquia formation This layer was packed with clam and oyster shells in a sandy, marine clay. Unfortunately, except for a few small but tough specimens lying on the beach, the shells were garbage, so rotted that they fell apart when picked up.
Something long and brown was sticking out of the clay. It was broken every few inches into a zig-zag shape, but somehow holding together. Bone had been replaced by iron minerals, and the result was tough in the thicker portions but brittle in the thin portions. It took me a long time to realize that I was looking at some sort of snout. As I dug deeper, it got narrower. At some point it dawned on me that the snout must have been attached to a skull which might be sitting on the beach right behind me, staring up at my muddy ass. When I turned around, I did find the base of the snout which I had previously taken to be a chunk of driftwood. But I never found the skull.
At home, I cleaned the snout of the mystery beast. My son, who enjoys puzzles much more than I do, helped glue it back together. Eventually, we found remains of two teeth, and it became clear we had a crocodilian. Thatís fun. A crocodile in Virginia! One tooth probably hadnít erupted yet, while the other had broken off low in the socket. The thin, brittle pieces that we had to glue back on were empty tooth sockets which consist of very spongy bone. Not a very impressive fossil. When collecting fossil clams and oysters, I can usually search long and hard for better specimens and keep trading up. But this was a chance for my son to learn that in vertebrate paleontology, fossils are usually so rare and you canít be picky: a laymanís hunk of garbage may be a paleontologistís new species.
This location had been far from shore when the Aquia formation was laid down. The crocodile had died, rotted, washed out to sea, and was chewed on by scavengers until it fell apart. After the skull separated from the rest of the bones, it rolled around on the ocean floor until most of the teeth had fallen out. When it was finally covered with sediments, the bones were crushed as groundwater leached them and the overlying sediments compacted. Fortunately, before turning into a small pile of phosphate garden fertilizer, the bones were replaced by iron minerals which mostly welded them back together again.
In just a few pounds of waste sandy clay, I found 5 small to medium-sized sharkís teeth. Some of the teeth were needle-sharp, so I donít think they had been concentrated by years wave action; they fell out and stayed where they landed. Without looking too hard, Iíve found similar sharkís teeth in the same Aquia formation on the Pamunkey river 40 miles to the south. Sharks must have been plentiful here, roughly 55-60 million years ago. The world was still recovering from the extensive extinctions which had taken place only 5 million years previously at the end of the Cretaceous, which left sharks once again as the top predators. Given the high concentration of sharkís teeth in the these sediments, and how much of the Aquia formation has been stripped away inside Potomac Creek, it is no surprise that the beach at Marlboro Point used to be a good place to find sharkís teeth.
As I left Potomac Creek, a bald eagle viewed the river from a tree atop Bull Bluff. On the way back, I paddled straight across a bend in the river rather than follow the shoreline. That was a mistake, because it meant I was exposed to the wind and had to pay the price for a soaked wetsuit. Wet neoprene slows down the heat loss so you donít feel an uncomfortable chill, but it still slowly sucks the heat out of you much faster than dry neoprene. The thought of caffeine and a cheeseburger in a warm room kept me going. By the time I got to the landing, I was very cold and stiff. Unloading many pounds of rocks, fossils, and gear warmed me up though. The food was great at Timís II, and I donít just say that because I was starving.
The described trip was 10 miles in 8 hours, including a few hours of beach-combing. The attractions of this location vary with the seasons. Deep winter is generally good for fossiling: winter storms tend to remove overlying sands, vegetation no longer obscures so much of the view, thereís minimal competition, and the water is generally clearer due to lack of algae. In contrast to much of the rest of the Atlantic Coastal Plain which sometimes seems like a whale graveyard, cetaceans are missing from this area because they hadnít yet evolved. If you want to catch the arrival of the ospreys, youíre going to have to get out in early Spring (mid- to late-March?) when the water is still dangerously cold. In summer, I was told there are a lot of power boats, but I presume one can stick to the shallows and not get run over. Fall might be nice, with cooler temperatures, still reasonably warm waters, and fewer power boats.
Small children drive up and down the streets in golf carts. As a parent, the sight made my hair stand on end. When they put a golf cart into gear, they are as likely to go forward as backward. Keep your eyes open and drive carefully.
I use http://tbone.biol.sc.edu/tide/ for tide predictions.
The CBOFS wind forecast for the Chesapeake Bay area can be found at tidesandcurrents.noaa.gov/ofs/cbofs/wind_forecast.shtml.
Jasper Burns discusses this area in "Fossil Collecting in the Mid-Atlantic States," c 1991.
A beautiful web page of Aquia formation finds can be found at www.fossilguy.com/sites/potomac/liv_col.htm
If your tolerance for pain is high, or youíre just weird like me, Ward and Powars discuss relevant stratigraphy at pubs.usgs.gov/circ/2004/1264/html/trip9/ and include links to USGS field trip stops in the vicinity.
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