The rate of decay is known and constant. The higher the proportion of argon-40, the older the rock. A mass spectrometer measures these ratios to establish a date. The older procedure known as potassium-argon dating-hitherto the best way of determining the age of something more than a few tens of thousands of years old-is done in two steps, requiring two samples. First, a chemical process determines how much potassium is present. Then a mass spectrometer looks at the second sample to see how much potassium has altered radioactively to become its daughter argon. The procedure suffers from the effects of weathering, which occur not only on the surface of rock but from grain to grain within. Argon slips away from zakelijke energie weathered material, thus changing its overall ratio to potassium and making any date determined by this method all the more approximate. Argon-argon dating is accomplished in the microscopic core of a single grain, beyond even the faintest disturbances of weather. The newer method is significantly more consistent and accurate than the older one. Results have shown-notably among the New England Seamounts-that where many potassium-argon dates fall into general approximation with Morgan’s calculations, the dates derived by argon-argon follow the track exactly. Eighty million years ago, in the Campanian age of late Cretaceous time, Great Meteor would have underlain the AmericanAfrican plate boundary, the Mid-Atlantic Ridge. Since then, Great Meteor has cut a gentle zakelijke energie vergelijken curve southward through the African Plate. From late Cretaceous, Paleocene, and Eocene time, the path is as well defined as it is on the American side. After the Eocene, the hot spot made the big seamount that bears its name. Then it began to go cold, to evanesce, to fade like a shooting star.
He named the place Aphrodisiac Spring. Over the decades, a stretch at a time, he completely circumambulated the skyline of Jackson Hole, camping where darkness came upon him, casting grasshoppers or Mormon crickets to catch his dinner. There were trout in the streams as big as Virginia hams. Sometimes zakelijke energie vergelijken he preferred grouse. (“I could throw a geology hammer through the air and easily knock off a blue grouse or a sage chicken. In season, of course. Hammer-throwing season. In the Absarokas, I threw at rattlesnakes, too. I don’t kill rattlesnakes anymore. I’ve come to realize they’re a part of the natural scene, and I don’t want to upset it.”) He carried no gun. He carried a bear bell instead. One day, when he forgot the bell, a sow grizzly stood up out of nowhere-six feet tall-and squinted at him. Suddenly, his skin felt dry and tight. (“Guess who went away.”) A number of times, he was charged by moose. He climbed a tree. On one occasion, there was no tree. He and the moose were above timberline. He happened to be on the higher ground, so he rolled boulders at the moose. One of them shattered, and sprayed the moose with shrapnel. (“The moose thought it over, and left.”) The Gros Ventre River entered the valley almost opposite the high Teton peaks. A short way up the Gros Ventre was a denuded mountainside, where seventy-five million tons of rock had recently avalanched and dammed the river. He saw glacial grooves running north-south, and remembered the levees that kept the Snake from spilling west. This suggested to him that the valley floor had tilted westward since the glacier went by. Curvilinear pine-covered mounds cupped the valley’s various lakes and zakelijke energie held them close to the Tetons. Each lake was at the foot of a canyon. Evidently, alpine glaciers had come down the canyons to drop their moraines in the valley and, melting backward, fill the lakes. Some of the effects of ice were as fresh as that; others were less and less discernible, dating back from one episode of glaciation to another, separated by tens of thousands of years. Love’s son Charlie, who teaches geology and anthropology at Western Wyoming Community College, was hiking one day in i967 along the ridgelines of the Gros Ventre Mountains when he discovered boulders whose source bedrock was fifty miles away in the Absaroka Range. If they were glacial, as they seemed to be, they recorded an episode until then unknown, and of greater magnitude than any other. The evidence remains scant, but what else could have carried those boulders fifty miles and set them down on mountain summits at ten thousand feet? David answered the question by coining the term “ghost glaciation.”
They dug some out, but many thousands died. Even on the milder days, when the temperature came up near zero, sheep could not penetrate the wind-crusted drifts and get at the grass below. The crust cut into their legs. Their tracks were reddened with blood. Cattle, lacking the brains even to imagine buried grass, ate their own value in cottonseed cake. John Love had to borrow from his bankers in Lander to pay his ranch hands and buy supplies. That spring, a flood such as no one remembered all but destroyed the ranch. The Loves fled into the night, carrying their baby, Allan.
At daylight we returned to the house. Stench, wreckage and debris met us. The flood had gone. Its force had burst open the front door and swept a tub full of rainwater into the dining room. Chairs and other furniture were overturned in deep mud. Mattresses had floated. Doors and drawers were already too much swollen for us to open or shut. The large wardrobe trunk of baby clothes was upset. Everything in it was zakelijke energie vergelijken . Around all the rooms at the height of the tabletops was a water mark, fringed with dirt, on the new wallpaper. Almost immediately, the bankers arrived from Lander. They stayed for several amiable days, looked over the herd tallies, counted surviving animals, checked John Love’s accounts. Then, at dinner one evening, the bank’s vice-president rubbed his hands together and said to his valued customer, his trusted borrower, his first-namebasis longtime friend, “Mr. Love, we need more collateral.” The banker also said that while John Love was a reliable debtor, other ranchers were not, and others’ losses were even greater than Love’s. The bank, to protect its depositors, had to use Love Ranch to cover itself generally. ‘We are obliged to cash in on your sheep,” the man went on. “We will let you keep your cattle-on one condition.” The condition was a mortgage on the ranch. They were asking for an interest in the land of a homesteader who had proved up. John Love shouted, ‘TH have that land when your bones are rotting in the grave!” And he asked the man to step outside, where he could curse him. To the banker’s credit, he got up and went out to be cursed. Buyers came zakelijke energie over the hill as if on cue. All surviving sheep were taken, all surviving cattle, all horses-even dogs. The sheep wagons went, and a large amount of equipment and supplies. John Love paid the men in the bunkhouse, and they left. As his wife watched the finish of this scene, standing silent with Allan in her arms, the banker turned to her kindly and said, “What will you do with the baby?”
The Medicine Bows are also like that-and the Uintas, the Bighorns. Their high flat surfaces, with peaks that seem to rest on them like crowns on tables, make no sense unless-as you look a hundred miles from one such surface to another across a deep dividing basin-you imagine earth instead of air: the Miocene fill, the continuous terrain. The high plateaus on the shoulders of the ranges, remaining from that broad erosional plane, have been given various names in the science, of which the most prominent at the moment is subsummit surface. “There’s a plateau above Union Pass in the Wind River Range that’s twelve thousand feet and flatter than a turd on a hot day,” Love recalled, and went on to say that at such an altitude in flat country he zakelijke energie sometimes becomes panicky-which does not happen if he is among craggy peaks, and seems to be a form of acrophobia directly related to the oddity of being in southern Iowa at twelve thousand feet. With those big crystals, the granite under our feet was about as coarse as granite ever gets, and, as a result, was particularly vulnerable to weather. Its pink feldspar, black mica, and clear glass quartz had been so exposed there for millions of years that gravels could be scraped off without the help of dynamite. The Union Pacific took advantage of this, ballasting its roadbed with pink granite for eight hundred miles. There was almost no soil in that part of the range-just twelve miles’ breadth of rough pink rock. “As you go from Chicago west, soil diminishes in thickness and fertility, and zakelijke energie vergelijken when you get to the gangplank and up here on top of the Laramie Range there is virtually none,” Love said. “It’s had ten million years to develop, and there’s none. Why? Wind-that’s why. The wind blows away everything smaller than gravel.” Standing in that wind was like standing in river rapids. It was a wind embellished with gusts, but, over all, it was primordially steady: a consistent southwest wind, which had been blowing that way not just through human history but in every age since the creation of the mountains-a record written clearly in wind-scored rock. Trees were widely scattered up there and, where they existed, appeared to be rooted in the rock itself.
Students’ ages ranged through one and two digits, and their intelligence even more widely. When Miss Waxham called upon Emmons Schlicting, asking, “Where does digestion take place?,” Emmons answered, “In the Erie Canal.” She developed a special interest in George Ehler, whose life at home was troubled.
He is only thirteen, but taller than Sandford, and fair and handsome. I should like to get him away from his family-kidnap him. To think that it was he who tried to kill his father! His face is good as can be.
At lunchtime, over beans, everyone traded the news of the country, news of whatever might have stirred in seven thousand square miles: a buffalo wolf trapped by Old Hanley; missing horses and cattle, brand by brand; the sheepherder most recently lost in a storm. If you went up Skull Gulch, behind the school, and climbed to the high ground beyond, you could see seventy, eighty, a hundred zakelijke energie vergelijken miles. You “could see the faint outlines of Crowheart Butte, against the Wind River Range.” There was a Wyoming-history lesson in the naming of Crowheart Butte, which rises a thousand feet above the surrounding landscape and is capped with flat sandstone. To this day, there are tepee rings on Crowheart Butte. One of the more arresting sights in remote parts of tl1e West are rings of stones that once resisted the wind and now recall what blew away. The Crows liked the hunting country in the area of the butte, and so did the Shoshonis. The two tribes fought, and lost a lot of blood, over this ground. Eventually, the chief of the Shoshonis said, in effect, to the chief of the Crows: this is pointless; I will fight you, one against one; the hunting ground goes to the winner. The chief of the Shoshonis was the great Washakie, whose name rests in six places on the map of Wyoming, including a mountain range and a county. Washakie was at least fifty, but fit. The Crow would have been wise to1 demur. Washakie destroyed him in the hand-to-hand combat, then cut out his heart and ate it. Despite her relative disadvantages as a newcomer, an outlander, and an educ::ational ingenue, Miss Waxham was a quick study. Insight was zakelijke energie her long suit, and in no time she understood Wyoming. For example, an entry in her journal says of George Ehler’s father, “He came to the country with one mare.
The phenomenon is obviously rare. A pulsating series of ice sheets seems to have been set up in the discernible history of the world roughly once every three hundred million years. It happens so infrequently that it must be the result of coinciding circumstances that could not stand alone as explanations. There are components fast and slow. The atmosphere has been gradually cooling for sixty million years. Possibly this is explained by the great orogenies that have occurred during that time-the creation of the Rockies, the Andes, the Alps, the Himalaya-and the volcanism that is associated with mountain building. Volcanic ash in the stratosphere reflects kantoor huren per uur amsterdam sunlight back into space. Also, the weathering of mountains, particularly their granites, brings on a chemical reaction that removes carbon dioxide from the atmosphere, diminishing the greenhouse effect and chilling the earth. In any case, the essential requirement is a cool summer. A little snow from one winter must last into the next. Eve:ry forty thousand years, the earth’s axis swings back and forth through three degrees. Summers are cooler when the earth is less tilted toward the sun. The sun, for that matter, is not consistent in the energy it produces. Moreover, the relative positions of the sun and the earth, in their lariat voyage through time, va:ry, too-enough for subtle influence on climate. Carbon dioxide also affects climate, and the amount of carbon dioxide in the atmosphere is not constant. Somewhere in such a list, which runs to many items, lie the simultaneous events that set the ice to growing. The change they bring is not at first dramatic. So critical is the earth’s temperature that a drop of just a few degrees will cause ice to form and spread. A cool summer. Unmelted snow. An early fall in some penarctic valley. An overlap of snow. A long winter. A new cool summer. An enlarged kantoor huren per uur eindhoven residue of snow. It compacts and recrystallizes into granules, into ice. Because it is white, it repels the sun’s heat and helps cool the air on its own. The process is self-enlarging, unstoppable, and once the ice is really growing it moves. Clear bands form near the base, along which the ice shears and slides upon itself in horizontal layers like the overthrust Appalachians.
With a microscope, you can see wood and bark, leaves and roots, seed coats and spores in bituminous coal-and even identify the plants they came from. Buried deeper and folded severely under pressure, it becomes anthracite. Anthracite is roughly ninetyfive per cent carbon and is so hard that it fractures conchoidally, like an arrowhead. Anthracite is iridescent, and burns with a clear blue flame. Coal is a record of tectonics. In late Pennsylvanian time, when the third set of mountains came up in the east and shed still another wedge of debris, kneading it into what had gone before, the great pressure, deep burial, and severe folding co-working space amsterdam produced the anthracites of eastern Pennsylvania, the pod-shaped coalfields of the folded-andfaulted mountains, which erosion and isostasy have lifted from the depths. Anthracite seams are often upside down or standing on end. Here in the Allegheny Plateau, burial was reasonably deep but tectonic pressures were minor, and the result is a lesser grade of coal. We stopped and tried to .collect some but had difficulty finding a sample that would not break up in the hand. “This is very flaky, high-ash coal,” Anita said. “People take it anyway. They come out to these roadcuts with buckets and take it home to burn.” We moved on through miles of coal-streaked roadcuts, and topographically to somewhat higher ground, where the coal seams were thicker. “As you go westward and upsection, you get more coal, because the rivers, growing older, became more co-working space eindhoven sluggish,” Anita said. “The floodplains became broader. There was more ponded water. There was more area for vegetation to grow and accumulatelike the lower Mississippi Valley today.” About five miles east of Clearfield, we stopped at a long, high throughcut full of coal. Draglines were working on both sides of the road. We chipped out some samples with rock hammers. The samples had integrity. “This is a hell of a coal,” Anita remarked. “Good commercial coal. To make it, there would have been about three thousand feet of Pennsylvanian stuff on top of it, which has been removed by erosion. Three thousand feet is the amount of overburden that will produce coal of this rank.” Stirred within by all these free B.t.u.s (twelve thousand per pound), I flailed at the cut with my rock hammer and filled a bag with good commercial coal, to take home and bum in my stove. Anita commented that coal dust was blacking my face. I wiped at it with a bandanna, and asked her, “Did I get it all?” She said, “Good enough for government work.” And we headed up the road.
“Even I said, ‘Oh, this piece peeled off the oncoming European-African plate and got dumped in here along with the elastics,'” Anita said, telling the story. “Everybody cited those papers. To this day they are called ‘marvellous, landmark papers.’ I could eat my heart out. The papers have been used as prime backup proofs of plate-tectonic applications in the northern Appalachians. Even now, a lot of the people who use the plate-tectonic model for interpreting the Appalachians are completely unaware that those papers were based on a paleontological misinterpretation.” Working in Nevada three years later, Anita had found Scandinavian-style conodonts of middle Ordovician age. Her husband, Leonard Harris, savored co-working space arnhem the discovery not for its embarrassment to his wife, needless to say, but for its air-brake effect on the theory of plate tectonics. “Now, how could that be?” he would ask. “How did this happen? Europe can’t hit you in Nevada.” From the Toiyabe Range she had taken the cool-water fossils, and moving east to other mountains-from basin to range-she had come to middle Ordovician carbonates that contained a mixture of conodonts of both the cool-water and the warm-water varieties, the American and the Scandinavian styles. Fartl1er east, in limestone of the same age in Utah, she had found only warm-water conodonts. She realized now the absoluteness of her error. Utah had been pretty much the western extremity of the vast Bahama-like carbonate platform that covered North America under shallow Ordovician seas. In western Utah, the continental shelf co-working space den haag had begun to angle down toward the floor of the Pacific, and in central Nevada the continent had ended in deep cool water. The conodont types differed as a result of water temperatures, not as a result of their geographic origins. Shallow or deep, conodonts of northern Europe were the same, because the water was cool at all depths. But here in America, with the equator running through the ocean where San Francisco would someday be, Ordovician water temperatures varied according to depth. Those apparently Scandinavian fossils were forming in deep cool water, the American ones in warm shallows. Moving east from the Toiyabe Range and into Utah, Anita had gone from outcrop to outcrop through the Ordovician world, from ocean deeps to the rising shelf into waist-deep limestone seas. She could see now that the thrusting involved in the eastern orogenies had shoved the cool-water conodonts and their matrix rock from the deep edge of the continental rise into what would be Pennsylvania.
The rock had bent again, and again we were moving upward through history. Now, though, the dip of the strata would reverse no more. In a dozen miles of ever younger rock, we climbed through the Paleozoic era almost from beginning to end. We went up through time at least three hundred million years and up through the country more than a thousand vertical feet, the last ten miles uphill all the way, from Bald Eagle Creek to Snow Shoe, Pennsylvania-the longest steady grade on I-80 east of Utah-while light, wind-driven snow began to fall. We had come to the end of the physiographic province of the folded-and-faulted mountains, and the long ascent co-working space amsterdam recapitulated Paleozoic history from the clean sands of the pre-tectonic sea to the dense twilight of Carboniferous swamps. We came up through the debris of three cordilleras, through repetitive sandstones and paper shales-Silurian paper shales, Devonian paper shales, Mississippian paper shales-crumbling on their shelves like acid-paper books in libraries. The shales were so incompetent that they would long since have avalanched and buried the highway had they not been benched-terraced in the manner of Machu Picchu. In other roadcuts, Catskill Delta sandstones, beet-red and competent, were sheer. We had gone through enough hard ridges and soft valleys for me not just to sense but to see the Paleozoic pageant repeatedly played in the rock. For all the great deformity and complexity, the mountains now gone had left patterns behind. The land rising and falling, the sea receding and transgressing, the ancestral rivers losing power through time had not just obliterated much of what went before but had always imposed new scenes, and while I, for one, could not hold so many hundreds of pictures well related in my mind I felt assured beyond doubt that we were co-working space eindhoven moving through more than chaos. The strata at the foot of the ten-mile hill had been nearly vertical. Gradually, through the long climb, they levelled out. They leaned backward, relaxed, one degree every two million years, until in the end they were Rat-at which moment the interstate left the deformed Appalachians and itself became level on the Allegheny Plateau.
Historical geologists, in the olden days, pieced together that narrative. Economic geologists, in their pragmatic way, cared less. In describing the minable Martinsburg-the blue-gray true unfading slate-C. H. Behre, Jr., wrote in i933, “Sedimentary rocks are often compressed from the sides through what may be loosely described as shrinking of the crust of the earth; how this shrinking is brought about is, for the present purpose, beside the point. It has the wellrecognized effect, however, that layers or bedding planes are wrinkled or thrown into ‘folds.’ ” By the nineteen-seventies, what Behre had loosely described was widely believed to be the impact of one continent colliding with another, as Iapetus, tl1e proto-Atlantic ocean, was closed and the suture of the two continents became the spine of the Appalachians. The conference room amsterdam successive pulses of orogeny-Taconic, Acadian, Alleghenianwere attributed to the irregular shapes of shelves and coastlines of the continents. Where they bulged, the action would have an early date, and especially where some cape, point, or peninsula had a similar feature coming from the opposite side. Such headlands, in advance contact, were said to have produced the Taconic Orogeny. Great bays, eventually coming against one another, set off the Acadian Orogeny. The Alleghenian Orogeny was the final crunching scrum, completing the collision. The apparent suture was a line running through Brevard, North Carolina, more or less connecting Atlanta, Asheville, and Roanoke, not to mention Africa and America. The Martinsburg seafloor and the underlying carbonate rocks had unquestionably been broken into thrust sheets and shuffled like conference room eindhoven cards. Uplifted with their Precambrian basement, they had, in perfect harmony with the Old Geology, become mountains that shed their sediments-shed their elastic wedges-and buried the Martinsburg deep enough to turn it into slate, buried the carbonates deep enough to turn them into marble. Thus, plate tectonics fit. Plate tectonics may have restyled the orogeny and dilapidated the geosyncline, but it fit the classical evidence.