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