Annals of the Former World

by John McPhee

  Indians first appeared in the Minisink about a hundredth of a million years ago. The carbonate rocks in the valley before us were close to five hundred million years old. They were one-ninth as old as the earth itself. For their contained conodonts, they were of special interest to Anita, and after the interstate dropped to the valley floor we stopped at roadcuts to collect them. The roadcuts suggested the ruins of blocky walls built by Hellenic masons. They were on both sides of the interstate and in the median, too. There were bluish-white and pale-gray limestones, dolomites weathered buff. Rock will respond to weather with varieties of color—rusting red in its own magnetite, turning green from trace copper. Its appearance can be deceiving. Geologists are slow to identify exposures they have not seen before. They don’t just cruise around ticking off names at distances that would impress a hunter. They go up to outcrops, hit them with hammers, and look at the rock through ten-power lenses. If the possibilities include the carbonates, they try a few drops of hydrochloric acid. Limestone with hydrochloric acid on it immediately forms a head, like beer. Dolomite is less responsive to acid. With her sledgehammer, Anita took many pounds of roadcut, and not without effort. Again and again, she really had to slam the wall. Looking at the fresh surface of a piece she removed, she said she’d give odds it was dolomite. It was not responsive to acid. She scraped it with a knife and made powder. Acid on the powder foamed. “This dolomite is clean enough to produce beautiful white marble if it were heated up and recrystallized,” she said. “When it became involved in the mountain building, if it had got up to five hundred degrees it would have turned into marble, like the Dolomites, in Italy. There is not a lot of dolomite in the Dolomites. Most of the rock there is marble.” She pointed in the roadcut to the domal structures of algal stromatolites—fossil colonies of microorganisms that had lived in the Cambrian seas. “You know the water was shallow, because those things grew only near the light,” she said. “You can see there was no mud around. The rock is so clean. And you know the water was warm, because you do not get massive carbonate deposition in cold water. The colder the water, the more soluble carbonates are. So you look at this roadcut and you know you are looking into a clear, shallow, tropical sea.”

  With dry land adrift and the earth prone to rolling, that Cambrian sea and New Jersey below it would have been about 20 degrees from the equator—the present latitude of Yucatan, where snorkelers kick along in transparent waters looking through their masks at limestones to be. The Yucatan peninsula is almost all carbonate and grew in its own sea. As did Florida. Under the shallow waters of the Bahamas are wave-washed carbonate dunes, their latitude between 20 and 26 degrees. At the end of Cambrian time, the equator crossed what is now the North American continent in a direction that has become north-south. The equator came in through the Big Bend country in Texas and ran up through the Oklahoma panhandle, Nebraska, and the Dakotas. If in late Cambrian time you had followed the present route of Interstate 80, you would have crossed the equator near Kearney, Nebraska. In New Jersey, you would have been in water scarcely above your hips, wading among algal mounds and grazing gastropods. You could have waded to the equator. West of Chicago and through most of Illinois, you would have been wading on clean sand, the quiet margin of the Canadian craton, which remained above the sea. The limy bottom apparently resumed in Iowa and went on into eastern Nebraska, and then, more or less at Kearney, you would have moved up onto a blistering-hot equatorial beach and into low terrain, subdued hills, rock that had been there a thousand million years. It was barren to a vengeance with a hint of life, possibly a hint of life—rocks stained green, stained red by algae. Wyoming. Past Laramie, you would have come to a west-facing beach and, after it, tidal mudflats all the way to Utah. The waters of the shelf would now begin to deepen. A hundred miles into Nevada was the continental slope and beyond it the blue ocean.

  If you had turned around and gone back after thirty million years—well into Ordovician time, say four hundred and sixty million years ago—the shelf edge would still have been near Elko, Nevada, and the gradually rising clean-lime seafloor would have reached at least to Salt Lake City. Across Wyoming, there may have been low dry land or possibly continuing sea. The evidence has almost wholly worn away, but there is one clue. In southeastern Wyoming, a diamond pipe came up about a hundred million years ago, and, in the tumult that followed the explosion, marine limestone of late Ordovician age fell into the kimberlite and was preserved. In western Nebraska, you would have crossed dry and barren Precambrian terrain and by Lincoln have reached another sea. Iowa, Illinois, Indiana. The water was clear, the bottom uneven—many shallows and deeps upon the craton. In Ohio, the sea would have begun to cloud, increasingly so as you moved on east, silts slowly falling onto the lime. In Pennsylvania, as you approached the site of the future Delaware Water Gap, the bottom would have fallen away below you, and where it had earlier been close to the surface it would now be many tens of fathoms down.

  “The carbonate platform collapsed,” Anita said. “The continental shelf went down and formed a big depression. Sediments poured in.” Much in the way that a sheet of paper bends downward if you move its two ends toward each other in your hands, the limestones and dolomites and the basement rock beneath them had subsided, forming a trough, which rapidly filled with dark mud. The mud became shale, and when the shale was drawn into the heat and pressure of the making of mountains its minerals realigned themselves and it turned into slate. We moved on west a couple of miles and stopped at a roadcut of ebony slate. Anita said, “Twelve thousand feet of this black mud was deposited in twelve million years. That’s a big pile of rock.” The formation was called Martinsburg. It had been folded and cleaved in orogenic tumult following its deposition in the sea. As a result, it resembled stacks of black folios, each of a thousand leaves. Just to tap at such rock and remove a piece of it is to create something so beautiful in its curving shape and tiered laminations that it would surely be attractive to a bonsai gardener’s eye. It seems a proper setting for a six-inch tree. I put a few pieces in the car, as I am wont to do when I see some Martinsburg. Across the Delaware, in Pennsylvania, the formation presents itself in large sections that are without joints and veins, the minerals line up finely in dense flat sheets, and the foliation planes are so extensive and straight that slabs of great size can be sawed from the earth. The rock there is described as “blue-gray true unfading slate.” It is strong but “soft,” and will accept a polishing that makes it smoother than glass. From Memphis to St. Joe, from Joplin to River City, there is scarcely a hustler in the history of pool who has not racked up his runs over Martinsburg slate. For anybody alive who still hears corruption in the click of pocket billiards, it is worth a moment of reflection that not only did all those pool tables accumulate on the ocean floor as Ordovician guck but so did the blackboards in the schools of all America.

  The accumulation of the Martinsburg—the collapsing platform, the inpouring sediments—was the first great sign of a gathering storm. Geological revolution, crustal deformation, tectonic upheaval would follow. Waves of mountains would rise. Martinsburg time in earth history is analogous to the moment in human history when Henry Hudson, of the Dutch East India Company, sailed into the bay of the Lenape River.

  Completing the crossing of the Great Valley of the Appalachians, Anita and I passed more limestones, more slate. Their original bedding planes, where we could discern them, were variously atilt, vertical, and overturned, so intricate had the formations become in the thrusting and folding of the long-gone primal massifs. The road came to the river, turned north to run beside it, and presented a full view of the break in the Kittatinny ridge, still far enough away to be comprehended in context but close enough to be seen as the phenomenon it is: a mountain severed, its folds and strata and cliffs symmetrical, thirteen hundred feet of rock in close fraternal image from the skyline to the boulders of a blue-and-white river. Small wonder that painters of the Hudson River School had come to the Delaware to do their best work. Geor
ge Inness painted the Delaware Water Gap many times, and he chose this perspective—downriver about four miles—more than any other. I have often thought of those canvases—with their Durham boats on the water and cows in the meadows and chuffing locomotives on the Pennsylvania side—in the light of Anita’s comment that you would understand a great deal of the history of the eastern continent if you understood all that had made possible one such picture. She was suggesting, it seemed to me, a sense of total composition—not merely one surface composition visible to the eye but a whole series of preceding compositions which in the later one fragmentarily endure and are incorporated into its substance—with materials of vastly differing age drawn together in a single scene, a composite canvas not only from the Hudson River School but including everything else that had been a part of the zones of time represented by the boats, gravels, steeples, cows, trains, talus, cutbanks, and kames, below a mountain broken open by a river half its age.

  The mountain touched the Martinsburg, and its rock was the younger by at least ten million years. Kittatinny Mountain is largely quartzite, the primary component of the hubs of Hell. In the posttectonic, profoundly eroded East, quartzite has tended to stand up high. The Martinsburg is soft, and is therefore valley. There is nothing but time between the two. Where the formations meet, a touch of a finger will cover both the beginning and the end of the ten million years, which are dated at about 440 and 430 million years before the present—from latest Ordovician time to a point in the early Silurian. During that time, something apparently lifted the Martinsburg out of its depositional pit and held it above sea level until weathers wore it low enough to be ready to accept whatever might spread over it from higher ground. The quartzite—as sand—spread over it, coming down from Taconic mountains. The sand became sandstone. Upward of fifty million years later, the sand grains fused and turned into quartzite in the heat and the crush of new rising mountains, or possibly a hundred million years after that, in the heat and the crush of more mountains. The Delaware River at that time was not even a cloud in the sky. Rivers of greater size were flowing the other way, crossing at wild angles the present route of the Delaware. Rivers go wherever the country tells them to, if the country is in vertical motion. The country would not be right for the Delaware for roughly a hundred million more years, and still another hundred million years would go by before the river achieved its present relationship with Kittatinny Mountain. No one knows how the river cut through. Did it cut from above through country now gone and lying as mud in the sea? Did it work its way through the mountain as two streams, eroding headward from either side, the one finally capturing the other? Was there once a great lake spilling over the mountain and creating the gap as its outlet? The big-lake idea has attracted no support. It is looked upon less as a hypothesis than as a theoretically possible but essentially foolish guess. There was for a time an ice-defended lake between the mountain and the Wisconsinan glacier. When the ice melted, the lake ran out through the Water Gap, leaving in evidence its stream deltas and seasonally banded bottom deposits. However, Glacial Lake Sciota, as it is called, was eight miles long and two hundred feet deep and could not have cut a gap through much of anything but sugar.

  The ice arrived twenty-three thousand years before the present. The terminal moraine is only ten miles south of the gap. Nonetheless, the ice front was something like two thousand feet thick, for it went over the top of the mountain. It totally plugged and must have widened the Water Gap. It gouged out the riverbed and left there afterward two hundred feet of gravel. Indians were in the Minisink when the vegetation was tundra. Ten thousand years ago, when the vegetation changed from tundra to forest, Indians in the Minisink experienced the change. The styles in which they fractured their flint—their jasper, chert, chalcedony—can be correlated to Anatolian, Sumerian, Mosaic, and Byzantine time. Henry Hudson arrived in the New World about four hundred years before the present. He was followed by Dutch traders, Dutch colonists, Dutch miners. They discovered ore-grade copper in the Minisink, or thought they did. Part fact, part folklore, it is a tradition of the region that a man named Hendrik Van Allen assessed Kittatinny Mountain and decided it was half copper. The Dutch crown ordered him to establish a mine, and to build a road on which the ore could be removed. The road ran up the Minisink and through level country to the Hudson River at Esopus Creek (Kingston, New York). A hundred miles long, it was the first constructed highway in the New World to cover so much distance. It covers it still, and is in many places scarcely changed. When Van Allen was not busy supervising the road builders, he carried on an elite flirtational minuet with the daughter of a Lenape chief. The chief was Wissinoming, his daughter Winona. One day, Van Allen went alone to hunt in the woods near the river islands of the Minisink, and he discharged his piece in the direction of a squirrel. The creature scurried through the branches of trees. Van Allen shot again. The creature scurried through the branches of other trees. Van Allen reloaded, stalked the little bugger, and, pointing his rifle upward, sighted with exceptional care. He fired. The squirrel fell to the ground. Van Allen retrieved it, and found an arrow through its heart. By the edge of the river, Winona threw him a smile from her red canoe. They fell in love. In the Minisink, there was no copper worth mentioning. Van Allen didn’t care. Winona rewrote the country for him, told him the traditions of the river, told him the story of the Endless Mountain. In the words of Winona’s legend as it was eventually set down, “she spoke of the old tradition of this beautiful valley having once been a deep sea of water, and the bursting asunder of the mountains at the will of the Great Spirit, to uncover for the home of her people the vale of the Minisink.” In 1664, Peter Stuyvesant, without a shot, surrendered New Amsterdam and all that went with it to naval representatives of Charles, King of England. Word was sent to Hendrik Van Allen to close his mines and go home. It was not in him to take an Indian wife to Europe. He explained these matters to Winona in a scene played out on the cliffs high above the Water Gap. She jumped to her death and he followed.

  On foot at the base of the cliffs—in the gusts and shattering noise of the big tractor-trailers passing almost close enough to touch—we walked the narrow space between a concrete guard wall and the rock. Like the river, we were moving through the mountain, but in the reverse direction. Between the mirroring faces of rock, rising thirteen hundred feet above the water, the gap was so narrow that the interstate had been squeezed in without a shoulder. There was a parking lot nearby, where we had left the car—a Delaware Water Gap National Recreation Area parking lot, conveniently placed so that the citizen-traveller could see at point-blank range this celebrated natural passage through a mountain wall, never mind that it was now so full of interstate, so full of railroad track and other roadways that it suggested a convergence of tubes leading to a patient in Intensive Care. We saw painted on a storm sewer a white blaze of the Appalachian Trail, which came down from the mountain in New Jersey, crossed the river on the interstate, and returned to the ridgetop on the Pennsylvania side. There were local names for the sides of the gap in the mountain. The Pennsylvania side was Mt. Minsi, the New Jersey side Mt. Tammany. The rock of the cliffs above us was cleanly bedded, stratified, and had been not only deposited but also deformed in the course of the eastern orogenies. Regionally, it had been pushed together like cloth on a table. The particular fragment of the particular fold that erosion had left as the sustaining rock of the mountain happened to be dipping to the northwest at an angle of some forty-five degrees. As we walked in that general direction, each upended layer was somewhat younger than the last, and each, in the evidence it held, did not so much suggest as record progressive changes in Silurian worlds. “The dip always points upsection, always points toward younger rocks,” Anita said. “You learn that the first day in Geology I.”

  “Do you ever get tired of teaching ignoramuses?” I asked her.

  She said, “I haven’t worked on this level since I don’t know when.”

  Near the road and the river, at the
beginning of the outcrop, great boulders of talus had obscured the contact between the mountain quartzite and the underlying slate. To move on through the gap, traversing the interior of the mountain, was to walk from early to late Silurian time, to examine an assembly of rock that had formed between 435 and 410 million years before the present. The first and oldest quartzite was conglomeratic. Its ingredients had lithified as pebbles and sand. Shouting to be heard, Anita said, “In those pebbles you can see a mountain storm. You can see the pebbles coming into a sandbar in a braided river. There is very little mud in this rock. The streams had a high enough gradient to be running fast and to carry the mud away. These sands and pebbles were coming off a mountain range, and it was young and high.”