Friday, December 26, 2014

Beach Fossils of the New York Bight

Beach Fossils of the New York Bight

Here's an article sufficiently outdoors published in The Paleontograph many months ago.

          Rockaway Beach, Queens, New York, is a slice of sand where routines of the everyday Big Apple meet the open Atlantic. Who would think this crowded beach is a great place to pick fossils after a storm? Between November and March, Nor’easters produce opportunity few care about, but those who do seek fossils find tokens of deep time. A group of about three dozen of us from the New York Paleontological Society kicked our way across the sand towards drift lines, having been informed that the treasure to seek is a blue crab fossil from the Pleistocene Epoch more than 11,700 years ago. We were assured that plenty of fossil shells would be found, but that the crabs, locked into place by clay having become rock, are uncommon.

          We could do better. Fossil lobster claws, gastropods, sponges, and other very rare specimens have been found on the Rockaway and Long Island beaches. But no one seems to expect them.

          We walked and picked shells that appeared ancient near the throat of the New York Bight, the indentation or oceanic pocket between Long Island and Queens, and the northern New Jersey beaches, cleaved by the Hudson Canyon. Ocean currents erode the coastline freeing fossils from sediment and sand; storms wash them onto the beaches. To some degree the canyon, 7217 feet deep at the continental shelf’s base, routes current in the direction of Rockaway Beach. At any rate, when the wind is strong from the southeast, fossils tend to grace drift lines. You could bet that collectors walked the beaches after Hurricane Sandy, and in fact a blog account confirms they did.

           We surely found Holocene Epoch specimens only a few thousand years old, and none of our collection seemed to be of the rare Lower Pleistocene exceptions two million years old that sometimes get reported. Most seem to come from the Pleistocene Ice Age, although interglacial periods warmed ocean temperature averages 3.6 to 19.8 degrees F beyond what they are now. That was news to my concern for global warming. It made me feel that we are less alone and unique than I had thought. On the other hand, the Wisconsin Glacier was the last of three ice masses, and ocean levels fell 400 feet lower than at present with ocean temperatures averaging 5.4 to 12.6 degrees F colder than they are now. Thus, the Hudson River carved what remains as the Hudson Canyon cutting through the continental shelf. Almost all of the fossil shells are of species alive and well in the Bight today such as surf clams, ocean quahogs, whelks, and moon snails. However, the Ponderous Ark and the periwinkle turn up while living specimens today are from North Carolina southward. This is clear evidence of those warmer waters of startling climatic shifts between glaciers.

          On our beach trek, I had been finding fossil shells that would have excited me as a boy, had I known this is what they are. North Carolina’s Outer Banks had yielded many finds for me at dawn before other beachcombers took their picks. Fossil shells may be available on any beach, although barrier beaches subject to erosion reveal the most. But how does one know how to identify them?

          They tend to be gray. Once a fossil shell was pointed out to me by an experienced collector, I knew them all. Discoloration can vary from gray, to off-white, to tan or rusty. They have no periostracum, the outer shell layer, nor ligament that holds together the bivalves, although there is more to being a fossil than these lacks of characteristics. On occasion, a blackened shell may be found that is not a fossil. The black shell particularly of clams and scallops is the result of years being buried in bay mud, which may be anoxic as is sometimes claimed to be the case. Sulphides stain the shell. However, black shell stain may not require much lack of oxygen. As a clammer in New Jersey’s Barnegat and associated bays many years ago, I found black mud had permanently blackened shells, as opposed to the whitish shells of those from sand, yet these live organisms were not without oxygen despite abundant sulphides. The smell left no doubt.

          As paleontology enthusiasts, we New Yorkers knew that what is essential to making a fossil shell is not the lack of a ligament—which is also usually not present in fairly recent, non-fossil bivalve shells—nor the absence of periostracum, but the mineralization of the fossil substance, whether of shell or crab that also characterizes gray clay concretion. Taphonomy determines specifically how and why fossils are preserved. In common parlance, a fossil is the remains of an organism turned to stone, but fossil shells are not exactly stones and don’t seem to be so at all, although they may be embedded in stone concretion such as common gray clay. Furthermore, shells are mineralized upon formation by organic processes—they’re made of calcium. So are bones, and fossil bones are classics. But the quality of mineralization is not the same in fresh shells or bones as those that have fossilized. The scientific term for the process is perimineralization, which implies the added ingredients from ground water penetrating the pores of bone over great expanse of time, or of brine transforming the mineral content of shells—porous enough—and hardening them to some degree.

          We all know fossils are special. We sensed this as children. Their stoniness is something I sensed as a five-year-old as having to do with a special process of some sort, and I was aware of immense time as a very young boy. It is a natural transformation that results in preservation, as if impermanence in nature is not the whole story. As a child, I found fossils in my Indianapolis, Indiana, backyard and contemplated them as symbols of something absolute within existence of which I am part. They suggested to me that I have something deep within myself that can weather the flux of life.

          True, the earth, the oceans, ourselves—none of this lasts forever. Yet the oceans and the entire planet are part of existence that cannot have come from nothing, nor become nothing. Everything transforms, as a fossil is a transformation of organic matter, given that it is not a fossil footprint or the like. A fossil suggests immortality in the way a work of art is a re-creation or transformation of experiential meaning which lasts for millennia. But nothing lasting would mean anything without particular search here and now, quite limited in time as we were by the few hours of our outing.

         For the time being, we clambered along the beach. We must have walked 15 or 20 blocks and I never expected to find one of those blue crabs, not that any evidence of the original coloration would be present if I did. We all seemed to search with sincere persistence. No one on the beach appeared to be there on a social lark. My son, Matt, had gained a fossilized lightning whelk in perfect condition. What’s the likelihood of this? I saw it first, standing out on the flat, wet sand as the wash receded, like a live creature crawling out of the primordial sea in full view to anyone who would look from the City of New York. I called out to my son. I pointed and he ran immediately to it. We celebrated and soon moved on, my suspecting that this would be our best find and perhaps it was, but everyone had the crab in mind.

          And then it appeared very simply at my feet. I saw the ribbed pattern underside, picked it up, and beheld what everyone else up and down the beach was looking for. I felt more odd than fortunate. This proved to be the only blue crab fossil found. The outing’s expert guide gave my son a blue crab piece he had found on earlier occasion as if to complement his father’s fortune. I was more grateful to the guide than for my own find. I don’t find myself truly avid about paleontology these recent years. But I was so as a young boy; it was important that my son take home a special token. What I remember best is Matt’s triumphant lifting of the whelk above the surf as if he could blow a clarion call through it.    

 Fossil lightning whelk
 Fossil oysters in clay concretion
Fossil blue crab (not blue-claw)