The Story of Our Valley, Chapter Two – The Cold Facts

By Kevin Wright©2011

Being relatively short-lived, we usually deal only with the most immediate effects of weather, be it snowfall, heat wave, drought, or flood. But taking the long view, our planet’s climate proves more unstable than we ordinarily comprehend—Despite seeming evidence to the contrary, we live in a glacial interstadial of unknown duration.

Our enjoyment of a relatively temperate zone is not unique; the climate record points to similar sunny vacations in an otherwise frigid past. On May 17, 1889, the Bergen Democrat announced that black oak trees in an excellent state of preservation had been dug from beneath the glacial clay near Little Ferry during excavation work on a large extension to the Terra Cotta Works. Since the factory was situated in “one vast bog meadow,” discovery of these buried trees astounded workmen and puzzled spectators. But, as we now know, continental glaciers flowed from the Laurentide Plateau of Quebec, Canada, to our latitude several times over the past two million years, only to retreat in balmier spells. Some respites have even been warmer than at present—Hippopotami waded the River Thames during the last mild interlude between Eurasian glaciations, which lasted 15,000 years, ending about 115,000 years ago. In our valley, it has been 11,500 years since the reign of the last Ice Queen.

Most recently, permanent snowfields grew in the north about 75,000 years ago, marking a resurgence of continental glaciation that slowly inundated one-third of North America. At its maximum, ice nearly 10,000 feet deep buried the Laurentide Plateau. At the peak of glaciation, sea level was 390 feet lower than today. The Hudson-Champlain Lobe of the ice sheet reached its maximum 21,750 years ago, making its most southerly advance through the Hackensack Valley. Since flowing glaciers act as conveyors, depositing boulders, clay, sand and gravel at their margins to form morainal hills, the end moraine of the Wisconsinan glaciation comprises a belt of short hills and waterlogged hollows forming the spine of Long Island. Crossing Staten Island between the Narrows and Tottenville, the end moraine stretches from Perth Amboy through Fords, Scotch Plains, Millburn, and Summit, standing as a gravel ridge, 380 feet high, in the valley between Chatham and Morristown. It passes Denville, Dover, and the north end of Budd Lake, crossing the Highlands through Saxton Falls, about a mile north of Hackettstown. Snaking across the Kittatinny Valley through Buttzville and Townsbury, it passes the Delaware River two miles below Belvidere.

An ice age is not without life—quite the contrary! With cool summers and mild winters, great and small beasts flourished upon a savannah of enriched floral diversity, without modern analogue, which spread south of the ice front. Herds of mammoth grazed open grasslands. Mastodon and stag-moose browsed patches of woodland and wandered the eastern forests, where spruce commingled with prairie vegetation. Undigested matter found in the stomach cavity of a mastodon skeleton uncovered in 1872 near Otisville, Orange County, New York, consisted of “fresh-looking and very large leaves, of odd form, and blades of strange grass, of extreme length, varying from an inch to three inches in width, and looking as if freshly cropped from the earth.” Back in the summer of 1882, David Essex unearthed the poorly preserved bones of a half-grown mastodon in black earth, two or three feet beneath the surface, about 300 feet southwest from the railroad depot at Corona, on or near the bank of Berrys Creek in Hasbrouck Heights. The bones were quite decayed, so that very few were recognizable. The best preserved were a piece of tusk, four or five inches long and two inches in diameter, and some broken teeth, much worn, as well as the crowns of others that had probably never developed roots and were still in the body of the jaw when the animal died. In January 1962, two high-school students discovered a mastodon tooth in a flooded construction ditch during construction of Route 80, near Polifly Road at the intersection of Routes 46 and 17. Scientists from the Bergen Museum of Arts and Science and the American Museum of Natural History recovered a nearly complete skeleton, minus feet and legs. An excellent specimen was uncovered in 1973 along the Dwarskill in Closter. The Pleistocene bestiary also included woodland musk oxen, sloths, stag elk, peccaries, horses, moose, bison, giant beavers, lions and tigers and bears.

When the climate warmed around 20,000 years ago, the Laurentide ice sheet began to waste away, receding an estimated 60 to 100 feet yearly up the Hackensack Valley. Halting now and again in colder interludes, the glacier abandoned a baggage train of rock plunder in its wake, ranging in size from clay particles, sand and gravel to great boulders. This stony mantle is called drift, a throwback to the quaint supposition that it was distributed on Noah’s Deluge. During the glacier’s begrudging retreat, icy meltwaters pooled between the decaying Laurentide Ice Sheet and the ridge of the end moraine, forming a succession of proglacial lakes in the Hackensack and Saddle River valleys. A morainal dam about 30 feet high across the Arthur Kill between Staten Island and New Jersey impounded Proglacial Lake Bayonne, drowning the lowlands surrounding Newark Bay for several thousand years. Steady erosion of the dam at Perth Amboy kept lowering the lake level until more resistant diabase was reached about five miles north of the original morainal dam, creating a new spillway for Proglacial Lake Hackensack, which was also contained by a dam across the Kill van Kull. Deltas of sand and gravel, found in Oradell, Westwood, Englewood and Hackensack, mark the mouth of feeder streams. Once the ice lobe receded far enough to the north, Proglacial Lake Hackensack drained through Sparkill Gap. For as long as the lake drained northeast, the lacustrine clays, south of Moonachie, were exposed to erosion.

Proglacial Lake Paramus formed when glacial deposits dammed the Passaic Valley between Clifton and Rutherford, just north of Route 3, impounding meltwaters in the Passaic and Saddle River Valleys. It drained through Musquapsink Brook, below Westwood, when that outlet was freed of ice. Ice also dammed the headwaters for Goffle Brook, temporarily creating Proglacial Lake Hohokus. Meltwaters were similarly impounded in the Pond Brook Valley at Franklin Lakes until released through the deglaciated Ramapo and Pond Book Valleys in Oakland.

Annual layers of sediment, called clay varves, settled to the lakebed in cold still water, forming summer layers of sand and silt, capped by thin winter layers of fine clay. Varves can be counted like tree rings to show the duration of these gelid reservoirs. Their enumeration in the Little Ferry Clay Pits record the passage of at least 2,550 years before the ice sheet withdrew north of Haverstraw, New York, exiting the head of our valley. Whenever the glacier paused in its recession, forming another moraine, chilly dust storms with winds approaching 100 miles per hour blew down across the tundra at its feet, piling up sand dunes and depositing beds of yellow loam, two or three feet thick, between the Palisades and First Mountain.

Generally, a mixed boreal forest grew once loamy soils developed. Deglaciated northern New Jersey progressed through the spruce parkland stage between 16,000 and 13,000 years ago. Red spruce, yellow birch and hemlock dominated Catskill forests by 13,800 years ago with cinnamon fern and grasses spreading underfoot. Yet the climate suddenly cooled again around 12,900 years ago (in the Younger Dryas), returning much of the northeastern United States and Maritime Canada to near glacial conditions for another 1,200 years. For a time, the retreating ice front stalled northwest of the St. Lawrence River, forming the St. Narcisse moraine.

A spruce and fir forest persisted until an abrupt warming and drying trend reached the middle Atlantic coast about 11,700 years ago, dissolving the continent-wide boreal forest and pushing the steppe-tundra farther north. As the last pockets of muskeg forest vanished, white and jack pines prospered for 600 to 1,000 years until deciduous species extended their range northward. Despite their survival through previous warm interludes, two-thirds of North American megafauna, including three kinds of elephants, giant ground sloths, species of horse and camel, giant rodents, dire wolf, saber-toothed tigers and other large predators, suddenly went extinct. Mammoths and mastodons vanished about 10,600 years ago, possibly under the combined pressure of human predation and habitat loss. While large browsing and grazing herbivores represent the majority of extinct fauna, in fact, the late Pleistocene extinction encompassed mammals, birds, reptiles and amphibians of all sizes. Amidst these changes on land, the ocean continued to rise, flooding estuaries along the Middle Atlantic coast, including the Hackensack and Passaic Rivers.

To understand how and when the Hackensack River became a tidal race, reaching inland from the head of Newark Bay to Van Buskirk Island, we must consider isostatic rebound of deglaciated terrain lying north of the end moraine. Relieved of the burden of ice, the land slowly rose about 3.5 feet per mile northward of the end moraine at Perth Amboy, gradually restoring the valley’s southward slant. It apparently rebounded to its present elevation by 6,500 years ago. Sea level also rose with the release of waters formerly locked up in glacial ice, but stood 43 feet below its present level 6,000 years ago. Reaching 33 feet below its present level by 5,000 years ago, woodland swamp, composed of alder, black ash and birch, thrived in the Hackensack Meadowlands, north of Secaucus (as marked by the formation of peat). Freshwater grasslands apparently stretched southward. The ocean’s rate of rise markedly slowed 4,000 years ago, so that it reached 16 feet below its present level 3,000 years ago and 9 feet below present level 2,000 years ago. Atlantic white cedar, a southern bog species, invaded the estuary during a brief warm, dry spell, called the Medieval Climatic Optimum, lasting from 950 to 1150 CE, when sea level likely reached its present stand. But the onset of cooling at the start of the Little Ice Age caused sea level either to stabilize or intermittently decrease over the next seven centuries. Since the close of the Little Ice Age—often dated to around 1850—sea level in New York Harbor has risen 15 inches. By the time of European contact, cedar swamps dominated one-third of the Hackensack Meadowlands, but have since vanished, due to the interaction of cutting and a general warming trend.

We look into the past to glimpse the future—for the past unknown is also the future unknown. Isn’t that the cold truth?