Long ago, Spain whirled in its continental drifting, made a hard right turn, and ran into France with a tectonic lunge. Rocks crumbled, and the Pyrenees became the zipper uniting these two great blocks. An ancient seafloor was raised in the process.
Today a part of that ancient ocean is exposed for all to see, but like Gomorrah and Sodom, that deep-sea bottom and its trove of skeletons has been turned to stone. Now it is a scenic park on the border between Spain and France, a coastal bit of the Basque country. On a very hot day a geologist prepares to hike this bit of coast in order to visit one of the world's most impressive Cretaceous-Tertiary boundary sites, a place where the great catastrophe ending the Age of Dinosaurs is preserved in dramatic fashion. To get there, he has to walk a pathway only the twentieth century could have built, a pathway containing clues not only to the past, but to the future—the future of evolution—as well.
He starts his trek along a busy scenic coastal road lined with "snacks" and open-air cafes, then strides onto a wide sandy beach covered with naked humans. A lone, futile sign proclaims Nudism Interdit! (Nudism Forbidden). It is July, a hot morning, and already throngs from nearby Spain are jostling with the German tourists for the best bits of littoral territory as they lather their naked bodies with sunscreen amid piles of discarded clothing. Every age and form of humanity spreads itself out to fry in the sun, and the geologist is an odd sight as he walks through the sand, at times stepping over and by the prone naked bodies, festooned as he is with the hammers, compasses, water bottles, packs, and other regalia of his trade. It is an odd sight to see a clothed man, let alone an equipped clothed man. Odder still, he is walking to work, while the rest of humanity is here to frolic in the waves, playing the odd game of Spanish paddleball. The tide of humanity washed onto this shore is oblivious to another flood of flotsam floating in from Spain with the tide: the flotillas of garbage caressing their legs and ankles in the warm Bay of Biscay as they unconsciously celebrate their dominion over a thoroughly tamed world. Not a single one of them worries about being eaten by some predator that day. It is a sure sign that a great mass extinction has taken place: only during mass extinctions do the predators disappear.
At the end of the beach a great rocky headland exposes pinstripes of strata, the Upper Cretaceous sedimentary beds he has come to sample. But the rocks rise precipitously and vertically up from the sea, leaving no path for the beachcomber to pass, so he must climb up onto the headland to get to his target site, still a half mile down the coastline. A well-worn path beckons upward near the end of the beach, and he follows it amid the sweet smell of beach and salt air. The neatly groomed track winds through bracken, then brings him next past a large fenced enclosure filled with children. As he passes closer, he sees that in contrast to the frolic and play normally associated with the young, these children are listless, slow-moving, or motionless. Some are wheeled by white-coated attendants. He realizes that this large outdoor reserve is for autistic and retarded children, all helpless and heart-wrenching in their plight. He walks slowly by, staring, but they take absolutely no notice of him. France has put its most pitiable next to the sea, in an exquisite set-ting—these children that in another age would die early, but here will live and in many cases breed, and in some cases perpetuate their disabilities. Natural selection is no longer at work for these, or any other, humans.
He ponders this experiment in future evolution as he finally passes by the manicured lawn, itself some new evolutionary joke of grass bred for looks, and the path begins to rise. Now a different assault on his senses occurs: the cool, sweet salt air is suddenly replaced by a gut-wrenching odor, a choking miasma. The path now runs next to the municipality of Hendaye's sewage treatment plant, its huge outdoor pools of cess slowly rotating in giant concrete cisterns. Unfortunately, there is no way over the headland except by this path. A littoral territory once the home of a small tribe of humans is now inhabited by tens of thousands of humans and visited each year by that many and more, and their combined fecal output is now so voluminous that it can no longer be simply dumped into the sea. So here it is "treated" and then dumped into the sea, creating a riotous explosion of algal growth in the shallow water around the sewage outfall pipes, an experiment in ecology that is utterly changing the intertidal and subtidal communities .along the coast as now bountiful phosphates and nitrates amid their rich liquid fertilizers putrefy the region.
Finally he is past this hurdle as well, and he enters a fairyland. High above the beach a great pasture unfolds: acres of manicured grounds, scattered trees, and the magnificent vista of the sea. Sitting above it all is a splendid spired castle, now housing French astronomers by all accounts, although no telescope can be glimpsed. He is now in the reserve called Abbadia, a huge park that was once the fertile fields of the adjoining castle, and he feels transported back to earlier centuries, with even more distant time travels just ahead. He shoulders through a herd of sheep—animals stupid and bizarre compared with their ancestors. Their fecal pellets lie everywhere, and he wonders if they are, after humans, the most common large mammals on the planet. He ponders the process called domestication and how all domesticated animals seem to have lost brainpower as they were sculpted by humans into the species that they have become. He imagines the world of 8,000 years ago as humanity began to populate it with entirely new types of animals and plants in the single greatest evolutionary experiment since the ancient mass extinctions.
As he walks across the high meadow in the sparkling summer sun, the twentieth century and its history once again intrudes. Amid the waving grass, grazing sheep, and linear hedgerows are the scattered remains of huge concrete bunkers, jumbled masses of fractured concrete and twisted rebar. The blockhouses were the work of the Nazis, part of the Atlantic Wall they built for defense, now nothing but large ruins of concrete littering the flat grounds like yawning caves or the litter of capricious giants. A movement within the first broken blockhouse he passes startles him; he expects a fox or dog, but a naked man slowly stands, watching him. He passes by, and another man can be seen in the next smashed bunker. Soon he realizes that the field is alive with half-seen men, all silent, many only partially clothed or, like the first, not wearing clothes at all. He understands suddenly that this park is the territory and cruising ground of the local gay community, a meeting place where the vacationers who come here, and the locals who live here, swap microbes and homogenize the world's infectious diseases. It is a microcosm of what is happening to the world's animals and plants. He wonders, how much of their behavior is genetic, and will that be a future of evolution?
He tops the crest of the headland and begins to drop down toward the sea. A steep and switchbacked trail makes a precarious path to the water's edge, where gently tilted strata are now exposed by the low tide. He strides out onto these rocks, inch- to foot-thick limestone layers packed with the most spectacular fossils.
Giant clams lie frozen in the strata. Not the giant clams of our age that are now seen as birdbaths in backyard gardens, but flatter clams, with huge oval shells as much as a yard in length. They are nothing like any clam now alive, yet once these fossils were dominant members of the Mesozoic sea bottom community. They are called inoceramids, and they are hallmarks of a time when dinosaurs ruled the land and ammonites swam the seas. These same ammonites, with coiled shells like that of the nautilus, are also found in the clam-rich strata, although they are never so numerous as the clams. The geologist notes a few, and begins to walk perpendicular to the bedding, and thus up through time.
It is a beautiful walk, with high cliffs of white limestone and reddish marl arching overhead, the sea slapping the rocks, and gulls wheeling about in noisy cacophony; no clouds mar the deep blue sky. When he has walked along the coast for about 40 meters, the most peculiar thing happens: the clam fossils begin to disappear. Soon they are rarely seen, and then they are gone altogether. They and their kind disappear not only from the strata on this seacoast but from all rocks dated at 67 million years old and less, in which they had been common. After a reign of over 170 million years, this type of clam suddenly goes extinct. The strata look the same, but the giant clams are gone.
The geologist continues his walk along the seacoast, moving relentlessly up through time as he crosses the tilted strata on the rocky beach. Fossils are still present, but they are relatively few in number. Most are sea urchins, although a few small clams and the rare but beautiful ammonites can be seen on this infrequently visited stretch of coast. He passes into a small bay, and the scenery changes. The tan to olive limestone he has been passing over is superseded by a gigantic wall of bright pink rock. There is a clear point of contact between the olive rock and this thicker, pinker limestone, and he moves into the bay to this contact. It is his goal this day. A thin clay layer several inches thick marks the boundary between the olive Cretaceous rocks and the pink rocks of the overlying Tertiary Period. This layer is also where the last ammonites can be found, while its counterpart on land is the stratum with the last dinosaur fossils. He smashes out a few fragments of this clay stone with his rock hammer and examines them with a powerful loupe. The clay contains a thin, rusty layer, and under magnification he can see that this thin layer is packed with tiny spherules, invisible to the naked eye but clearly visible even under the low magnification of the loupe. He is looking at bits and pieces of Mexico, on an extended European holiday after being blasted into space by the great asteroid impact that ended the Mesozoic Era 65 million years ago. In the warm sun, on this perfect day, he stretches out on the rocks, one hand on the last of the Cretaceous, the other slightly above it, on the oldest rocks of the Tertiary, spanning two eras, and imagines the scene:
1 he asteroid (or comet—who knows!) is perhaps 10 kilometers in diameter, and it enters the Earth's atmosphere traveling at a rate of about 25,000 miles an hour. Yet even at such great speed it can be visually followed as it traces its majestic path down through the atmosphere before finally smashing into the Earth's crust. It is so large that it takes a second for its body to crumble into the Earth. Upon impact, its energy is converted into heat, creating a non-nuclear explosion at least 10,000 times as strong as the blast that would result from mankind's total nuclear arsenal detonating simultaneously. The asteroid hits the equatorial region in the shallow sea then covering the Yucatan, creating a crater as large as the state of New Hampshire. Thousands of tons of rock from ground zero, as well as the entire mass of the asteroid itself, are blasted upward, creating a bar of white light extending up from the Earth into space. Some of this debris goes into Earth orbit, while the heavier material reenters the atmosphere after a suborbital flight and streaks back to Earth as a barrage of meteors. Soon the skies over the entire Earth begin to glow dull brick red from these flashing small meteors. Millions of them fall back to Earth as blazing fireballs, and in the process they ignite the rich, verdant Late Cretaceous
The Age of Dinosaurs ended when an asteroid crashed into the Earth at Chicxulub on Mexico's Yucatan Peninsula.
forests; over half the Earth's vegetation burns in the weeks following the impact. A giant fireball also expands upward and laterally from the impact site, carrying with it additional rock material, which obscures the sky as fine dust is transported globally by stratospheric winds. This enormous quantity of rock and dust begins sifting back to Earth over a period of days to weeks. Great dust plumes and billowing smoke from burning forests also rise into the atmosphere, soon creating an Earth-covering pall of darkness.
The impact creates great heat, both on land and in the atmosphere. The shock heating of the atmosphere is sufficient to cause atmospheric oxygen and nitrogen to combine into gaseous nitrous oxide; this gas then changes to nitric acid when combined with rain. The most prodigious and concentrated acid rain in the history of the Earth begins to fall on land and sea, and continues until the upper 300 feet of the world's oceans are sufficiently acid to dissolve calcareous shell material. The impact also creates shock waves spreading outward through the rock from the hole the asteroid punches in the Earth's crust; the Earth is rung like a bell, and earthquakes of unprecedented magnitude occur. Huge tidal waves spread outward from the impact site, eventually washing ashore along the continental shorelines of North America, and perhaps Europe and Africa as well, leaving a trail of destruction in their wake and a monstrous strandline of beached and bloated dinosaur carcasses skewered on uprooted trees. The surviving scavengers of the world are in paradise. The smell of decay is everywhere.
For several months following this fearsome day, no sunlight reaches the Earth's surface. After the initial rise in temperature from the blast itself, the ensuing darkness that settles in causes temperatures to drop precipitously over much of the Earth, creating a profound winter in a previously tropical world. The tropical trees and shrubs begin to die; the creatures that live in them or feed on them begin to die; the carnivores that depend on these smaller herbivores as food begin to die. The "middle life" of the Mesozoic Era—a time beginning 250 million years ago— comes to the end of its nearly 200-million-year reign.
Following months of darkness, the Earth's skies finally begin to clear, but the mass extinction—the deaths of myriad species—is not yet over. The impact winter comes to an end, and global temperatures begin to rise—and rise. The impact has released enormous volumes of water vapor and carbon dioxide into the atmosphere, creating an intense episode of greenhouse warming. Climate patterns change quickly, unpredictably, and radically around the globe before the Earth's temperatures regain their normal equilibrium. They swing from tropical to frigid,
Debris from the K-T impact would have created continent-size fireworks before raining ash and darkness on the planet for years.
then back to even more tropical than before the impact, all in a matter of a few years. These temperature swings produce more death, more extinction. The dinosaurs die out, as do most—but not all—mammals. Most life in the sea is exterminated.
The end-Cretaceous catastrophe was global, immense. It shares many characteristics with the Permian extinction so vividly exposed and expressed in the Karoo: both affected the Earth so much that they changed the nature of sedimentary rocks of the time. In France that change is clear—the latest Cretaceous rocks are green in color; the K-T boundary layer is dark mudstone, and the recovery rocks of the succeeding Tertiary are the thick pink limestone. Such changes occur only in the face of great chemical changes.
The geologist ponders the site. The boundary beds may have been a product of this single calamitous event, the impact of a huge asteroid with the Earth 65 million years ago. But the other victims on this Hendaye beach, the giant clams found in the strata beneath this site, were killed off 2 million years prior to the impact. What killed them? Was their passing (and that of many other creatures at the same time) the result of an Earth already stressed? It appears that the Cretaceous-Tertiary mass extinction, like the great Permian extinction that preceded it, was multi-causal.
The geologist's reverie is broken by a great rumbling sound, and he notices, for the first time, the giant culvert snaking down from the cliffs above, a pipe three feet in diameter, ending in the small bay he is standing in. A great deluge of brown water belches from the pipe, filling the bay with treated sewage from the plant on the bluff above. The Cretaceous rocks and the overlying Tertiary strata are quickly covered, clues to a long-ago extinction fouled with the last meals of the good people of Hendaye.
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