What would it be like to walk on the ocean floor? You may be surprised to learn that about half of New Jersey was once the bottom of the sea!
Dr. Emile DeVito, New Jersey Conservation Foundation’s staff biologist, explained that at the end of the Cretaceous period 65 million years ago, when the Earth’s climate was much warmer, the Atlantic Ocean covered most of what today we call the Outer Coastal Plain.
New Jersey’s “high points” today - Mount Mitchell, Telegraph Hill, Arney’s Mount, Mt. Holly and other sandstone hills that dot the western boundary of the Outer Coastal Plain – were river mouths and estuaries.
“A shallow ocean covered nearly all of southern New Jersey, and many thousands of feet of sand and clay - eroded from giant mountains to the northwest - accumulated on the seafloor over the eons,” Emile said. Tiny bits of mineral washed from the Adirondack Mountains and were carried down the ancient Hudson River, finally settling onto the ocean floor over a dozen miles inland from today’s barrier beaches.
Today, if you travel 15 miles westward from Long Beach Island, you’ll find unusual pine trees known as Pygmy Pines, near the tiny village of Warren Grove where Burlington and Ocean County meet. If you hike to the “hilltops,” which are really undulations in the ancient seafloor, you can see over the tops of the dwarf or Pygmy pine trees for miles!
How did the ancient seafloor become today’s Pine Barrens?
In the last couple of million years, during the Paleolithic Era, the climate changed and polar ice caps grew immense. A series of glaciers advanced and receded every few hundred thousand years. Sea level dropped dramatically, exposing sand. When the sea retreated to its lowest level, New Jersey’s coastline was located dozens of miles east of its current location, out at the now submerged edge of the Hudson Canyon!
During the driest cold spells that lasted for thousands of years, Southern New Jersey was a polar desert, with unrelenting winds rolling off the glaciers to the north and sweeping south at up to hurricane force for months on end.
In this polar desert climate, the winds evaporated what little ice accumulated on the sandy soils. Sandstorms were frequent, blowing sands out of drying wetlands into tall dunes. These Paleolithic dunes can be found in the Pine Barrens today, and form critical habitat along with the wetland features that they often parallel.
As the ice retreated, these barren lands were blanketed with tundra-like grasses and shrubs, followed by spruce-fir forests like those of interior Canada, then finally covered by today’s familiar species.
At the end of the Wisconsin glacial period about 12,000 years ago, forests spread from the south coast of the United States, bringing new species to New Jersey.
Some plants and animals found in New Jersey’s Atlantic White cedar swamps, like Boreal redback voles, and in the Pygmy Pines, like Broom crowberries, are holdovers from about 7,000 years ago, when southern New Jersey looked more like the coast of Newfoundland.
But most came up from the south. After the ice age, Northern Pine Snakes slithered through coastal pine forests that are now beneath the Atlantic Ocean, finding safe places to nest and hibernate in the deep windblown sand of Paleolithic dunes. Pine Barrens treefrogs hopped all the way from the Deep South, finding vernal ponds and blue holes for breeding in the ice-age sculptured landscape.
Abundant Sweetbay Magnolia trees had no trouble getting here, since their seeds are readily dispersed by fruit-eating migratory birds. The heavy seeds of the endangered Pickering’s Morning Glory may have been aided in their movement north, by being accidentally carried in the guts of leaf-eating mammals working their way up the coast.
The tiny seeds of southern orchids and federally-endangered American Chaffseeds had no trouble blowing in the wind, but today the natural wildfires they depended upon to shape their habitat for 50 centuries seldom occur.
The unbroken coastal forest connecting New Jersey to the southern states exists no more. Sea level rise created great bays and severed the forest connection between New Jersey, the Delmarva Peninsula, and eastern Virginia and the Carolinas.
But the Pine Barrens is still a proverbial Noah’s Ark of southern species, now isolated from their southern counterparts at the northern end of their range!
The genetic isolation of the Pine Barrens forest has already allowed a few species of plants and insects to become unique to this state we’re in. DNA studies would reveal more unique species, and more are evolving! Today, we must somehow, against mounting odds, continue to preserve enough contiguous Pine Barrens habitat, and find a way to live side-by-side with these plants and animals in a fire-dependent ecosystem.
Next time you hike in the Pine Barrens, look down at the sandy ground and remember that you’re walking on an ancient sea floor!
POSTSVernal pools: Now you see 'em, now you don't