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DESERT TIME -- A JOURNEY THROUGH THE AMERICAN SOUTHWEST


 

Table of Geologic Time

Era

Period (or Epoch) Years before
the present
CENOZOIC Pleistocene Epoch
Tertiary Period
recent-2 million
2-65 million
MESOZOIC Cretaceous Period
Jurassic Period
Triassic Period
65-136 million
136-190 million
190-225 million
PALEOZOIC Permian Period
Carboniferous Period
Devonian Period
Silurian Period
Ordovician Period
Cambrian Period
225-280 million
280-345 million
345-395 million
395-430 million
430-500 million
500-570 million
PRECAMBRIAN   570 million-4.6 billion

Chapter 35:  moving mountains
West Central New Mexico

We are eating fajitas on top of twenty-two thousand feet of sediment washed into the Rio Grande rift. Down there, a massive wedge of basement rock is falling away like a keystone dropping down while some tectonic Samson pushes the arch apart. This rift runs all the way from the Mexican state of Chihuahua to Sawatch, Colorado, and is variable in width; from thirty miles wide near Albuquerque it thins to a couple of miles here, in Socorro.

The rift began to open some twenty-eight million years ago, when the Colorado Plateau to the west began to pull away from the craton -- stolid basement rock -- to the east. Both craton and plateau are moving west, mind you, but the crust of the continent here is extending, expanding, the plateau is moving faster, like a raft pulling ahead in a slow drift race.

"Over time the intensity of the extensional forces has varied," OJ says. "There's been no major volcanic activity here for the last million years. There's quiescence now. It's comfortable right now."

And there's a hint of a smile, but only a hint. Geologists work in a different time frame than other people do, so a million years may not be long, but he's right about the comfort. The fajitas are very good. The tortillas are soft and fresh, the salsa fragrant, the beer is cold, and the rocks will wait for us to finish up.

OJ is slim, athletic, grizzled, and his sense of humor is considerable but dry. He's a field man by trade, an outdoorsman, a pragmatist. He's a geologist with the New Mexico Bureau of Mines and Mineral Resources in Socorro; it's one of the largest state bureaus of mines in the country. Right now he's in charge of remapping the entire geology of the state, putting onto one large multicolored sheet all the field research done by anyone before and after the last geologic map of New Mexico was done. Since I barged into his office eight months ago, on a whim, in a tizzy, a steady correspondence has led to this: to a Mexican dinner in the rift and a two-day journey, starting tomorrow at dawn, northwest into the Zuni Mountains and through the country where he has mapped the rocks, himself, for years.

We are starting in the rift: extended terrain. I picture it something like this: like a shelf of books between bookends. Pull the bookends apart -- extend them -- and the books will tilt, "faults" opening between volumes. Some volumes will flop nearly flat on their sides; these are low-angle faults. Some will stand nearly straight up: these are high-angle faults. Where the bindings have slid past each other, the spines coming out of plumb, you have strike-slip faults. If you look at your extended shelf from the side you will see the bedrock of basin and range in cross section: peak and valley, range and basin (you have to imagine those book-corner peaks weathering down and filling the V-shaped hollows nearly flush), and you realize you've seen this before, in fact you've seen it everywhere, in all these deserts (except on the Colorado Plateau; though it wraps the plateau on three sides).

In any case the plateau isn't considered desert at all by some folks -- they call it semiarid brushland or grassland -- though other folks agree it's a true subset of the Great Basin desert to the northwest. (Just to confuse the issue the names are almost the same, but the things they name are not. Great Basin desert is a biological unit. Basin and range physiographic province, the extended terrain, is a geological unit. Most of it does happen to be desert, though.)

This basin and range physiographic province runs from southern Idaho and Oregon through most of Nevada, through southern California, central Arizona, south through West Texas, and up here into central New Mexico, clear on past the Great Sand Dunes National Monument in Colorado, where this journey began.

"The eastern margin of the rift is the eastern margin of basin and range," OJ says. "The rift is part of it. It's an asymmetrical graben. It lies like a ribbon, the down-warping greater on one side than the other. It's the grand expression of basin and range."

The bookshelf isn't lying on a solid surface anyway, but on something with the flexibility of a waterbed, a hot waterbed: seething rock, fluid magma. Where the books bob up past each other, these are thrust faults. The convection cells down there, the slow swirls of heated rock, push the basement rocks sideways as well as up and down, now this way, now that way. This is plate tectonics.

Before the terrain began to extend itself there was something else, the opposite: compression. From seventy to forty million years ago, compressive forces had the upper hand here, and that was the time of the Laramide Orogeny -- orogeny meaning mountain-building time. It was during the Laramide that the Rockies rose into being.

"The Colorado Plateau? It has a thicker underlying crust. It's a microplate, in the parlance of the tectonics people. It's only four, five hundred miles across."

We order coffee. OJ goes on, softly:

"The plateau resisted that compressive deformation during the Laramide Orogeny. It also resisted the tensional forces which came with extended terrain, later on. There are a few little drape folds over thrust faults in the basement, drape folds in the overlying sediments. Those monoclines are the hallmark of the Colorado Plateau. But for the most part it has behaved as a coherent mass. Resisted breakup. There's less volcanism. Basin and range is shot through with volcanism."

Tomorrow we'll be climbing the west edge of the rift toward the plateau, onto the plateau, across the rim of the microplate, through a region of chaos. Mountains have been created there; massive fields of volcanoes. And mountains have moved. They have moved up and sideways and have since worn, partly, down, so that you can read the pages. Those mountains are The History of New Mexico going back hundreds of millions of years. This is where we're going.

***

The next morning just past sunrise Magdalena Peak is to our left, we've come up the rift, past the fields of little cinder cones and past the road to Water Canyon. The mountains are nearly pure volcanics, made of rhyolite and ash-flow tuff.

"Ash-flow tuffs are nasty rocks. No soil formation," OJ says.

Round the corner of the range is Magdalena, a dusty shabby near-ghost town now. Though people do live here most businesses have left.

"Magdalena here was a bustling community at the turn of the century. Great mining country. Ranch country. This old brick hotel? Used to be full, all the time. The boardinghouse, too. Railroad workers, cowboys in the wintertime, miners. Cowboys in the winter ... they were bored, troublemakers, found moonshine, raised hell. Wasn't a fun life. Isn't it funny how ranching has been romanticized?"

To the south and west lies the immense Mogollon-Datil volcanic field that formed, or began to form, at the end of the Laramide Orogeny, forty million years ago, and went on forming for another fifteen million years or so, on and off, through the beginning of basin and range faulting; they mark the transition, so to speak. They're a subprovince unto themselves, a volcanic pile.

"There's nothing else exposed down there," he says, meaning no other rocks, the volcanoes have buried the lot. "It's a place of repeated and extensive volcanism. There's nothing else exposed." The mountains here are the outliers of that Mogollon-Datil field, fringing the plateau. Tres Montosos is to the right: three peaks made of ash-flow tuffs.

"Ash-flow tuffs are nasty rocks," he says again. "When they came, they hugged the ground. They were a high-velocity base surge, shot out as a dense superheated fast-moving cloud. The expanding gasses and the sheer volume of material shot them out horizontally. We're talking extremely high temperatures and extremely violent events. It's not something you'd want to witness. Everything in their path was volatilized. These things go on for thirty, forty miles."

***

We come to the Plains of San Augustin, ringed by volcanic mountains, a huge, treeless, utterly flat space where the National Radio Astronomy Observatory has its Very Large Array, the largest radio telescope in the world. The VLA consists of twenty-seven antennas, each one eighty-two feet in diameter and weighing two hundred and ten tons, according to the sign. Spread on their railroad tracks in this vastness, they look like mushrooms.

"During the last pluvial there was a shallow glacial lake in here," OJ says. "Tall ponderosa pine and spruce surrounding a glistening mountain lake, crystal clear water ..."

The heat is already burdensome, so is the dust. The lake was just a moment ago, ten thousand years, no more. We cross fingers of old dune sand, shorelines grown over by rabbitbrush.

"And all it would take is four, five inches of rainfall, and pretty soon the groundwater would intersect the surface, and that's all you need to form a lake. Then they'd have to put each of those VLA units on a canoe."

***

We're at Pie Town; a town that, like other towns out here, hardly exists. We turn north on a dirt road.

"This is what rural New Mexico is all about. Gravel roads. Pinyon and juniper. Abandoned homesteads. A few ranches, skunks, buzzards, coyotes."

We're on the Spears Formation now; water-laid volcanics worn and washed off the Datils to our east, laid down in a ragged tongue of debris as the volcanic mountains rose.

"These volcanic sediments cover the transition onto the Colorado Plateau. We're getting on it. We're on the feather edge of Spears. We'll be coming up on Cretaceous sediments. Older sediments. Seventy to ninety million years old."

We're going back in time. The rift, the volcanoes, the volcanoes wearing down, and now back to what they rifted and spewed onto and wore down over: the level-laid sediments of plateau. We're high here. Pie Town lies at nearly eight thousand feet.

"The entire sequence is upper Cretaceous, younger than one hundred million years. They're all associated with the presence of a shallow interior seaway."

Geologists call it the Western Interior Seaway. This was the coast then, traversed by rivers and swampy backwaters, sometimes flooded by the sea, then exposed again. The evidence is this: on the far side of the Zuni Mountains the Dakota Sandstone alternates -- is interbedded -- with Mancos Shale, a rich organic shale laid down in shallow seafloor.

"The seacoast came and went for twenty million years. It oscillated for two hundred and fifty miles. In the marine rocks we find marine organisms, ammonites and bivalves, molluscs. In the nonmarine and marginal rocks we find coal-bearing sequences, dune sandstones, tidal channel sandstones."

***

It's a picture I can visualize, something I can see. Shallow seafloor, wavelets of lagoon, swamps, estuaries: coast. Now over the wide sky of these North Plains a line of squalls approaches, dark flat clouds against the blue, a seam of convection cells. There is a dusty smell of rain.

The country is subdued, less harsh and angular. We're crossing a ridge: a small volcanic dike with shallow sills, outlier of eruption, the dike being molten basalt injected up into a slim fault, the sill being molten basalt injected sideways between seaway layers. There's the abandoned village of Hickman; collapsed and collapsing log cabins. There are a few Brangas cattle, a sprinkling of rain hard as pebbles, a smell of dust.

"Since seventy-five million years ago, the sea was in regression to the present ocean basins. The North American continent has not been inundated by ocean since."

After the Western Interior Seaway left, the Rockies rose.

***

To the west is a rough line of darkness: the North Plains lava flows and the low black peaks of the Zuni Bandera volcanic field. The cones are less than three million years old, some active as recently as a thousand years ago. They are the newest thing around. They lie in a southwest-northeast-trending line that ends, to the northeast, in volcanic Mount Taylor. The line of these volcanoes parallels a kind of "bone" embedded in the earth's crust. It's an ancient bone, and runs straight through the softer body of the plateau. It's part of what some people call the Jemez Lineament. It's made of basalt that is very dark and dense and rich in magnesium. It's five hundred million years old, or older.

Along the lineament, strike-slip faulting made a fracture zone, a deep crack.

"It was ultimately utilized as a magma conduit," OJ says.

In other words, it let volcanoes come on up.

***

It's past noon, nearly one P.M. There's a dark swarm ahead on the horizon. It's the edge of the malpais, the bad country, and it is that: a recent basalt flow from the Zuni Bandera field, two or three hundred thousand years old, forty miles across from east to west, one slim lobe flowing into Arizona. The newest malpais near here is the McCartys flow near Grants, just to the north, and that's less than a thousand years old. I remember the malpais of Carrizozo, months ago. The stuff is rugged, spiky, full of holes and edges, an annealed froth. Picture a torn loaf of bread forty miles across and made of iron.

"You'd shred a pair of Nikes in one day out there. Leather-soled stuff would be torn to shreds out there," he says.

No road crosses the malpais. Here, at The Narrows, the malpais has crowded close to the base of a cliff of pale sandstone: Cebolleta Mesa, a jut of pale rock visible. for miles and miles, its walls made of pinky-cream sandstones typical of the plateau. The top of the mesa is brown Dakota Sandstone, the oldest of the Cretaceous layers, laid down when the Western Interior Seaway was first advancing. It's made of sands washed down by rivers onto sinking coastal plain. Below the Dakota lies something else. Older. A high streaky bulk, spectacular stripes of salmon and cream, the foundation and main body of the mesa, made of a rock sixty million years older than the sea: this is Zuni Sandstone. Jurassic rock.

When the Zuni Sandstone was deposited here, it was an immense field of dunes. You can see this. The Zuni is made of tiny interbedded layers; winds sifting sand over dune crests a hundred and sixty million years ago.

All across the Southwest the Jurassic is famous for its thick deposits of dune sandstone. This was drier, hotter, real indubitable desert, nothing growing anywhere. This was more equatorial then; the continent has since drifted northward. These were huge seas of dunes, their sands oxidized -- rusted -- by a dry continental climate.

The salmon-colored Navajo Sandstone of Zion, of Monument Valley, the Echo Cliffs, and so on, cropping up all across Navajo country? That's one of the greatest deposits of dune sand in the world. Jurassic dunes. And the peach-colored de Chelly Sandstone of the canyon of that name, immense cliffs pocked with Anasazi ruins? The cross-bedding made by Jurassic winds is so visible there it hurts. Sixty million years before the Western Interior Seaway came, this was like the core of North Africa, one sand sea after the next, and the seas of sand were pink and cream and red.

The sixty million years? They're gone. Worn away. Pages torn out. Here, Dakota Sandstone sits on top of Zuni Sandstone. This is known as an unconformity.

"Sixty million years is a big-time unconformity. All the upper Jurassic and lower Cretaceous is missing here."

***

To map the rocks you carry a Brunton compass to give direction and location, and an inclinometer to measure the dip angle of deposits. However they were laid down, formations rarely lie perfectly flat. You go from one bedrock outcrop to another. You put the contacts, where one formation ends and another begins, on a topographic map.

"You cover six, eight miles a day on foot. Doing little traverses. You can cover a lot of ground in six weeks."

What comes to light is structure. There are fold axes: an anticline, where a formation has domed up. A syncline, where the rocks have sagged. You find the crests and troughs. Where the formations have draped over a fault like blankets over the edge of a bed, that's a monocline, and then you look for the rollover, the steepest limb. You map faults: high- or low-angle, thrust, reverse thrust, strikeslip. You look for the blocks that fault patterns might encompass. You look for the evidence that the faults are basement involved, or not -- basement being old deep crust of the continent itself. Did formations become detached and crumpled on top of basement rocks, scrunched like blankets on an unmade bed?

You have a ten-to-twelve-power hand lens so you can see the grain of the formation and measure it against the grain-size chart: fine, medium, coarse; angular or rounded. Angular sand grains are water-laid, more rounded ones have been bounced by wind. You have an acid bottle to test for chemistry, looking for the carbonate fizz.

Thick sediments with no volcanic rocks; those have fossil fuel potential. The volcanics -- and native rock reheated and metamorphosed by volcanic heat -- may have rare minerals associated with them; base or precious metals. Sulfide-bearing rocks often have metals complexed with the sulfides: zinc, lead, copper.

You need a pocketknife and a topo map.

"A topo map is a geologist's best friend," OJ says. "What you really need is your topo sheet, a four-wheel-drive vehicle, and a promise of a cold beer at the end of the day."

***

We come to Grants, Uranium Capital of the World -- malpais keeping us company all the way. Then after less than ten westward highway miles we go south again on rural Route 53, along the far side of the malpais.

"No road crosses the malpais. And this, this road here, this is the ancient way. Coronado followed it from Zuni to Acoma in 1540."

We climb Bandera Crater to the continental divide -- 7,882 feet here, the sign says -- then turn up on forest roads to parallel the divide. To climb the Zuni Mountains. The roads are rough. These are rugged tracks and back ways. This is OJ's country. He names the outcrops without looking up from the track. A forest rises: pinyon, juniper, ponderosa. We pass abandoned cabins; so many I lose count.

***

An ancient complex of rocks underlies the works, here and just about everywhere else on the continent, and on all continents, and this is aptly known as basement. It was formed in the Precambrian era, more than five hundred and seventy million years ago.  So many things have been built -- layered, blown, washed over, spewed out -- on top of it since, that this basement is easy to forget. It's a storehouse of fragments from a planet that, if you were to go there, you would never recognize. It had no life on it larger than microscopic single cells. The atmosphere would asphyxiate you with the first breath. There was no ozone shield in place, oxygen being scanty, so the earth was clawed by the naked ultraviolet rays of the sun. You wouldn't last there for a nanosecond. Mountains grew and were worn down, all the same. The basement complex is made of ancient rock that has since been reheated to taffy consistency and has stretched, compressed, warped, recrystallized, remelted, and rewarped. It is also made of granite domes, molten magma that surged up, stopped, crystallizing slowly in place, deep down. This is basement.

Mule Deer and Pinyons:  Mule deer have black tail tips and oversized ears. At dawn and dusk they wander out to feed in little groups of fawns and does, and if you move quietly they will let you get close. They are most common in dry open forests of pinyon pines and junipers; canyons, foothills, the scattered woodlands of desert mountains are their habitats, with the bighorns on the scarps above and the pronghorns on the flats below, though of course there is some overlap. The pinyons themselves are low and rugged and their cones drop meaty nuts the size of beans, food for wildlife as well as for people. When you look out between the scattered trees of this dry forest, you can often see the desert below, the color of dust.

As the Zuni Mountains rose, the layers on top of their rising tilting basement wore away. Here the Dakota Sandstone is long gone. The Zuni dune Sandstone is gone. We're on the Chinle Formation, back in a vast river system more than two hundred million years ago. There are mudstone floodplain deposits, sandy layers of grit, pebble in what were stream channels. This was laid down by a huge west- by-northwest-trending river that drained all of what was West Texas, most of New Mexico, much of Arizona and southwestern Utah emptying into the sea at what was then the West Coast: northwestern Nevada. The river ran here for ten to fifteen million years. The Chinle Formation that the river left here is soft, gray, greenish, flaky and granular, easily eroded. It is (before erosion) twelve to fifteen hundred feet thick.

We're still climbing, not steadily, up and down now through forest, and the Chinle vanishes, returns, vanishes, then it's gone. After it goes, the early Triassic is absent; more pages torn out (or maybe never written at all here), and we're in the Permian. The rock is suddenly pale pinkish gray, dense, and the surface has the peculiar "melted" look of karst terrain, full of holes. This is San Andres Limestone. This is shallow sea bottom. This was laid down, here, in deep quiet seawater when the Capitan Reef began abuilding in West Texas. There are about one hundred and eighty feet of it here, or were, before erosion. There are fossils in the San Andres. Fossil species are something OJ knows, species being clues, both definite and general clues, to time.

Then the limestone is gone, too, and we're further back in the Permian, at the edge of that sea, that Permian sea known to geologists as the Sundance Seaway. We're back before that sea covered all this up. There are thin layers of sandstones, redbeds so called because of their color. First the Glorieta Sandstone, then the Yeso Formation. and below it the Abo Formation. Marginal marine deposits. Old red dunes. We're at the edge of the Sundance Seaway. At the edge in place, and time.

The Sundance ran all the way across Oklahoma and, of course, Texas.

***

At 6:35 P.M. -- I wrote this down -- somehow a historical moment, though why should it be? Since I knew last night that this was when we were going; but it's not the same when someone tells you how the book ends as getting to the ending having read the pages -- or at least the chapter headings and subtitles and having looked at some of the pictures -- at least enough to be able to follow the gist of it, the story. Because we're back to the beginning. We're on Precambrian granite. Basement rock. It's the color of deep rust, and is decaying into square-edged gravel in the ponderosa needles. As if nothing were fantastic about it at all. Just granite decaying away calmly up here in the forest.

***

Right here, the ancient beam of the Jemez Lineament pushed a chunk of basement rock and all the rock on top of it, too, up thousands of feet into the air and, still pushing, swung it partly around like a pole pushing off-center on a massive crate. All the layers on top of this basement chunk -- thousands of feet worth -- wrinkled like a pile of rugs. Here at the mountaintop these layers have all worn away. They're gone. On the west side of the Zunis, the wrinkle still shows. Delta sands, floodplain muds, seabeds full of fossil shells, coastal sandstones left ripple-marked by ancient tides or cross-bedded by ancient winds, thin coal seams of backwater swamps; more than two thousand feet of sediments -- hundreds of millions of years' worth of New Mexico history -- stand straight up on end. This is known as the Nutria Monocline.

***

Of course this history-of-the-earth tale is the kind of story that you can see in other places, though it would never be the same in other places. And I've seen it all right, but in fuddled bits, not right the way through. In the granite gravel on top of the Zuni Mountains I stand around not knowing what to do with myself. Not even thirsty anymore. I'm back on a planet that I don't even recognize, and it's the same one I've lived on all along.

We go a little farther and make camp on San Andres Limestone, on the lip of the mountain where it drops away and becomes the Nutria Monocline. We'll go through the monocline tomorrow. We'll see the rocks all stood on end. We'll go on and visit the ranch of old Max Garcia, whose parents came from Cebolleta Mesa and homesteaded the place when his father was in his early twenties and his mother barely seventeen. When OJ was doing his field work up here, he spent months living in a trailer close to Max, using Max's spring for water. Max's parents cleared all the fields by hand. Max himself built the huge log barn. He's an old man now, alone up here, none of his children want the place. But he hates the trees coming into the pastures -- he's down to thirty cattle, from two hundred, but the ranch is still full of peacocks. The peacocks have the same slim patrician somehow Spanish grace as Max.

We'll go through the Zuni village at the Upper Nutria River, the neat stone houses made of Gallup Sandstone; forward in time, now; the Gallup is Cretaceous, younger even than the Dakota.

We'll follow the Nutria River through its confluence with the Pescado, to the Zuni. Beyond Zuni Pueblo we'll be on the Chinle again.

"The Cretaceous sediments are way up, over our heads, thousands of feet," OJ will say.

"In the past."

"Yep. "

We'll visit an oil rig that's just begun drilling on a miniature monocline, where the sedimentary Yeso may (don't know, yet) make a trap for oil or gas. The oil will be (if it's there) from marine organisms that once lived in the Sundance Seaway. We'll meet the oil men, meaning the money men (it costs fifty thousand dollars to drill a thousand feet), one from New Orleans and the other from Pecos, Texas, both wearing ten-gallon hats and cowpoke boots. We'll meet the mud logger in his trailer, with his Nikon microscope for inspecting the drill cuttings. We'll meet the drillers, they'll be naked from the waist up and will be wearing bandannas around their heads. The monocline was mapped by OJ so he'll have a proprietary interest and will ask a lot of questions, and he'll stand around for a long time grinning in the mud and ruckus.

It will become clear that OJ knows everyone in these parts, not that there are a lot of folks to know. When we stop at the Fence Lake Store (Fence Lake almost doesn't exist, either; whether it never did or doesn't anymore isn't clear, but it does exist just enough), Carl Quintana, who runs the place, will give us flyswatters and plastic  mugs with "Fence Lake Store" written on them, and will chat with OJ for a long time while I forage for candy bars. The store has canned goods, watermelons and potatoes, pinto beans, wool plaid hats, Day-Glo work gloves.

When we leave, OJ will say:

"There are four cultures here. Mexicans, Indians, homesteaders, and Mormons. Mormons gravitate to productive farmland. So we've fallen back here to the old-line Hispanic families and good ol' boy rancher types. There's one ninety-some-year-old Anglo lives out here, sits on milk pails, burns wood, hangs out at the Fence Lake Store. Urban folks might have headed for an old folks home but rural folks are too cussed independent!"

***

We'll be on the Fence Lake Formation, then. Huge volcanic boulders the size of heads, the size of chairs. Round boulders. A huge deposit.

"Younger than the Spears. Laid down five to twenty-five million years ago. Guess by what."

"Water."

"Yep. Shed down off the Mogollon-Datil pile. Must have been way up there, then. High, high mountains. And water! These were hellaceous rivers."

And that will be the end, almost.

More gravel roads. Then we'll come to it, surrounded by mesas topped with basalt. In the belly of the volcanics, there it will be. A perfectly round hole in the country. A cinder cone, popped open with a single phenomenal blast twenty-five thousand years ago. No time ago at all. It will be a mile and a quarter across, the floor of it one hundred and seventy-five feet below the surface. Like a kindergarten volcano. In coming up from deep deep down, from below even the basement, it tapped into some saline plumbing. After it burst, the crater -- the maar as these things are called -- filled up with salty water: brine. The brine evaporated. Still does. The cone now holds anywhere from one hundred to seven hundred feet of pure salt, topped by a few feet of slushy brine. It's a sacred place to the Zunis. They own it now. Didn't always. Coronado's report of 1549 states: "The Cibola Indians have very good salt which they bring from a lake a day's distance away," and Onate reported to Spain, not much later, that the salt was "the best that Christians have discovered," which says it all, or almost all. According to the Zunis, this salt lake is the place of origin of their people. This is where they came from. It is the home of the Salt Mother. It is the center of the world.

***

Where the salt comes from is a mystery, though. When OJ tells me about the cinder cone and the maar -- Zuni Salt Lake, it's called -- up there in the evening at our camp on the mountain rim, I don't quite believe him. I believe the cold can of beer because I have it in my hand. I believe the basement granite, too, because there are pieces of its sharp-edged gravel wearing a hole in the pocket of my jeans.

As for the forces that swung the mountains of Zuni like a jibboom and wrinkled up two thousand feet of sedimentary rocks like so much tissue ... the less said the better. Only that my conclusions are nothing new and are roughly this: we are tiny, we live a tiny time, our understanding of nature may span the breadth of a juniper needle; and for power all our megatonnage amounts to no more than the capacity to tweak the nose hairs of a minor deity, a godlet living out its days in some retirement pantheon in the salubrious climate of a celestial desert, perhaps.

I blink at the notion, presently so much on thoughtful people's minds, that we can, through our life-style, change climate. Perhaps we can, perhaps we have and we will, but it won't be much in the general scheme of things. We think too much of ourselves. If dried lakes and deserted cities aren't enough to convince us that climates change anyway; if ancient reefs heaved into the cores of continents aren't enough to tell us that they always have; then nothing would ever be enough to humble us into perspective.
 

Executive Summary

Observations show that warming of the climate is unequivocal. The global warming observed over the past 50 years is due primarily to human-induced emissions of heat-trapping gases. These emissions come mainly from the burning of fossil fuels (coal, oil, and gas), with important contributions from the clearing of forests, agricultural practices, and other activities.

Warming over this century is projected to be considerably greater than over the last century. The global average temperature since 1900 has risen by about 1.5F. By 2100, it is projected to rise another 2 to 11.5F. The U.S. average temperature has risen by a comparable amount and is very likely to rise more than the global average over this century, with some variation from place to place. Several factors will determine future temperature increases. Increases at the lower end of this range are more likely if global heat-trapping gas emissions are cut substantially. If emissions continue to rise at or near current rates, temperature increases are more likely to be near the upper end of the range. Volcanic eruptions or other natural variations could temporarily counteract some of the human-induced warming, slowing the rise in global temperature, but these effects would only last a few years.

Reducing emissions of carbon dioxide would lessen warming over this century and beyond. Sizable early cuts in emissions would significantly reduce the pace and the overall amount of climate change. Earlier cuts in emissions would have a greater effect in reducing climate change than comparable reductions made later. In addition, reducing emissions of some shorter-lived heat-trapping gases, such as methane, and some types of particles, such as soot, would begin to reduce warming within weeks to decades.

Climate-related changes have already been observed globally and in the United States. These include increases in air and water temperatures, reduced frost days, increased frequency and intensity of heavy downpours, a rise in sea level, and reduced snow cover, glaciers, permafrost, and sea ice. A longer ice-free period on lakes and rivers, lengthening of the growing season, and increased water vapor in the atmosphere have also been observed. Over the past 30 years, temperatures have risen faster in winter than in any other season, with average winter temperatures in the Midwest and northern Great Plains increasing more than 7F. Some of the changes have been faster than previous assessments had suggested.

These climate-related changes are expected to continue while new ones develop. Likely future changes for the United States and surrounding coastal waters include more intense hurricanes with related increases in wind, rain, and storm surges (but not necessarily an increase in the number of these storms that make landfall), as well as drier conditions in the Southwest and Caribbean. These changes will affect human health, water supply, agriculture, coastal areas, and many other aspects of society and the natural environment.

This report synthesizes information from a wide variety of scientific assessments (see page 7) and recently published research to summarize what is known about the observed and projected consequences of climate change on the United States. It combines analysis of impacts on various sectors such as energy, water, and transportation at the national level with an assessment of key impacts on specific regions of the United States. For example, sea-level rise will increase risks of erosion, storm surge damage, and flooding for coastal communities, especially in the Southeast and parts of Alaska. Reduced snowpack and earlier snow melt will alter the timing and amount of water supplies, posing significant challenges for water resource management in the West.

Society and ecosystems can adjust to some climatic changes, but this takes time. The projected rapid rate and large amount of climate change over this century will challenge the ability of society and natural systems to adapt. For example, it is difficult and expensive to alter or replace infrastructure designed to last for decades (such as buildings, bridges, roads, airports, reservoirs, and ports) in response to continuous and/or abrupt climate change.

Impacts are expected to become increasingly severe for more people and places as the amount of warming increases. Rapid rates of warming would lead to particularly large impacts on natural ecosystems and the benefits they provide to humanity. Some of the impacts of climate change will be irreversible, such as species extinctions and coastal land lost to rising seas.

Unanticipated impacts of increasing carbon dioxide and climate change have already occurred and more are possible in the future. For example, it has recently been observed that the increase in atmospheric carbon dioxide concentration is causing an increase in ocean acidity. This reduces the ability of corals and other sea life to build shells and skeletons out of calcium carbonate. Additional impacts in the future might stem from unforeseen changes in the climate system, such as major alterations in oceans, ice, or storms; and unexpected consequences of ecological changes, such as massive dislocations of species or pest outbreaks. Unexpected social or economic changes, including major shifts in wealth, technology, or societal priorities would also affect our ability to respond to climate change. Both anticipated and unanticipated impacts become more challenging with increased warming.

-- Global Climate Change Impacts in the United States -- A State of Knowledge Report from the U.S. Global Change Research Program

These are campfire thoughts, mind you. A quilting bee of fragments falling into place. Because there's more, too. Because if the plentiful strewings of shit and bones left by grand beasts, beasts that we can never see, aren't enough to prove that extinctions are common, that lives are fragile, then we can never take lives seriously enough to save them. Not even our own. If the agonizing bankruptcies and deep harmonic strengths of Native cultures -- and of our own rural land-based culture, too, which is our native lifeway and the roots of our survival -- aren't enough to prove that citifying "civilizing" culture can be hypocritical at least, blind at best, then the cities will die. What difference will that make to the desert? Not much.

We look too much to our own creations as the source of curse or blessing. In cities, among people, it is too easy to look to ourselves. And to our gods, perhaps. Though if we do carry a godlike spirit in us, then maybe too many of us too much of the time have stopped listening to its balancing wisdom. Our sins against nature are sins against ourselves. This is certain. But other things are certain, too.

The grandeur of spaces stretched and dried to a felt of sand, or sage, or gyp-grama, opens the skull; the chaw of mountains layered to the horizon is beauty to stun dumb.

OJ says:

"Another beer?"

"Thanks."

And then:

"After you live out here for a month at a stretch, like I did back in eighty-one, and then you go back to Albuquerque ... when you get there, you think: my God! People live in places like this!"

And we laugh, because I understand this, the first lesson the desert teaches anyone. Is: beware the leaving.

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