Pressure Cooker

July 17th, 2013


  Pictured above is the inner north wall of Cerro Colorado. This structure is about one kilometer (3300 feet) in diameter, and about 110 meters (360 feet) deep. You can just barely make out our vehicles in this image. They are the small white dots, across the crater, along its rim. A dark lava flow can be seen in the distance.

  Just across Arizona’s southern border, on the way to the Gulf of California, lies one of the Sonoran Desert’s most spectacular geologic features – the Pinacate Volcanic Field. Few of the many thousands of tourists that each year visit the party-place we call Rocky Point (Puerto Peñasco to the Mexicans) even know that it is there. That’s a good thing, too, for part of its beauty is its desolation. It is one of the most similar places to the surface of the Moon that you will find anywhere on Earth. Not because of its loneliness, though.

  From the highway to the coast, you cannot see that out there in that barrenness lie a number of impressive craters. Get up in the air, however, and it looks much like what you see through a telescope focused on the lunar landscape. Massive, ring-shaped, and deep, those craters show that the now-quiet countryside was once a pretty violent place.

  Previously, I’ve written about the explosive San Francisco Peak(s) of northern Arizona, towering above Flagstaff, and not hard to miss at all. But the craters of the Sierra Pinacate region of Sonora are not readily apparent until you are right there.

  This area lies within a Mexican National Park – the Parque Natural del Gran Desierto del Pinacate – which also features a sea of sand dunes, lava flows, and a number of volcanic cinder cones. It is not the kind of place you want to venture into light-heartedly, with your passenger car and beach clothes. Take a lot of water – that is some good advice, too.

Basalt lava flows cover valley floors within the Gran Desierto del Pinacate.

  To me, the craters are the most interesting things to see, and these are some really good ones. They are different from craters on the Moon, though, because the lunar ones were formed by impact – asteroid, meteoric. Same with Meteor Crater, near Flagstaff.

  The Pinacate craters were created by relatively shallow explosions in the crust of the Earth. They are a type different even from the volcanic craters and cones of northern Arizona, like Sunset Crater. In “geology-speak”, they are called maars, and these happen to be some especially young ones.

  The Gran Desierto (Grand Desert) is a dry, dry place. Yet, deep underneath the sparse desert scrub that does exist there, is groundwater, or very recently was, apparently. That water occupied layers of rock, in turn overlying lower rock units that become hotter with depth.

  Remember, and I’ve written about this in many other articles as well, that this part of North America is very active, geologically. Earth’s crust is and has been breaking up in this zone, and the fractures run deep. Molten rock can move upwards along those fractures, eventually making its way to the surface, hence the cinder cones and lava flows.

Crater Elegante is too wide<br />
to fit into one picture.

  In the past, here in the Pinacate Field, some of that molten rock moved upwards, and encountered groundwater deposits (known as aquifers). When it did, it converted the water instantaneously to steam – massive amounts of it – and the ground literally exploded outward, creating maars.

  Then, at least in some of the cases in the Parque Natural, those exploded chambers collapsed back into themselves, expanding them additionally into structures known as calderas – gaping holes in the ground. There are at least ten of these maar / calderas in the Volcanic Field.

  It is possible that humans witnessed some of the eruptions. Hohokam relics have been found along some of the erosion surfaces in the area. Studies show that the blasts occurred within the last few million years, and some only within the last few thousand years. Very jagged, black, and barren, the basalt lava formations that you drive by between the craters look like they flowed yesterday.

  As you can see, the starkness of the vista adds much to the otherworldly look of this place, so if you can’t make it to the Moon (and most of us won’t have that chance), you can at least get an idea of the lunar scenery by visiting the Pinacates.

  Breathing is easier there, too.


September 28th, 2012


  That the native inhabitants of the Americas had a different way of relating to the landscape is without much question. Their sacred sites and temples were placed in special geographic places.

  But what led to such a view? Could it be because that within their culture, they value fitting in with nature, not trying to change it? Seeing yourself as part of something is, to be sure, not the same as seeing yourself as separate from something.

  What we are all part of is a vast web of life that covers our planet. So far, based on the current state of scientific knowledge, it is that web which makes Earth distinct and unlike any other place we know of in the Universe.

  That “coating” of life includes plants, of course, and animals, fungi, and microbes of many kinds. Life lives in the air, in the water, and on the land. And, now it turns out, inside the planet, too. It thrives even in the rocks.

  In last month’s GeoStory™ (“Top Coat” — also in, I talked about life on the surface of rocks. However, that layer pales in comparison with what is underneath.

  Geologists and other scientists are beginning to realize that in what we once thought was barren, lifeless stone, is, in many cases, teeming with microorganisms. Some of those microscopic life-forms are strange indeed, and can feed from the rocks, without needing air or light.

  Sedimentary rocks (which are deposited by water or wind) usually have small pore spaces within. These pores can and many times do, contain water, oil, or gases. It is from this porosity that we pump groundwater, petroleum, or natural gas.

  Other kinds of rocks, by nature of the way they formed, have no pores per se. But they frequently contain fractures of all sizes, and water or hydrocarbons can occupy those cracks, too. Living things – microbes – can occupy them all.

  Various experiments over the past few decades have shown that certain bacteria can flourish in such environments. No sunshine. No fresh air. Sometimes stiflingly hot temperatures. Yet, there they grow and multiply. The only thing that seems to be required in all cases for life to exist is the presence of water. We have lots of that, and we know now that our neighbor planet Mars probably does (or at least once did), too.

  No wonder that space scientists look with intense interest upon such organisms. If they can exist in the rocks here, then maybe they can exist in the rocks of Mars, or other worlds, too. And for earth scientists, such “deep life”, is leading to a new level of understanding of how the world works.

  Based on data derived from deep-drilling projects, the late, brilliant, and controversial Cornell University astronomer Thomas Gold did some calculating. His reasonable estimates indicate that the top five kilometers (about three miles) of the Earth’s crust could contain as much as 200 trillion metric tons of live bacteria. This would be like covering the entire planet with a layer of bacterial organisms one and a half meters (approximately five feet) deep!

  This is more than a hundred times as much living mass (called biomass) as all of the other life-forms (including us) of the world put together! If aliens from another world were studying our planet, they would easily conclude that the rocks are the most alive part of it.

  There are, of course, visible remnants of past subsurface life: coal beds, fossils, tar sands and other petroleum formations. There are metallic mineral deposits which seem to have been “helped along” in their genesis by organic life.

  Professor Gold has even suggested that diamonds come from deep-seated organic materials, and we know today that diamonds must form in an environment at least 75 miles down. If hydrocarbon compounds can exist that far below us, and the rocks are alive, so to speak, then the Earth we all know and love is a very unusual place.

  Perhaps, though I can’t prove it, life gravitates towards other life, and I don’t mean just to eat it, either. Maybe it’s a stretch, but think about it the next time you pull into an almost-empty parking lot, and you park right next to another person’s lonely vehicle.

  The Indians (and to be fair, many other ancient cultures) may have subliminally recognized the existence of places where life was, in effect, somehow concentrated nearby, though not apparent on the surface. Some of those places became special to them.

  Ponder that the next time you are out in the great outdoors somewhere, and “feel alive”. Look around and see what makes that so, and then look down, too.

  It may all be underneath you.


August 26th, 2012


  Life has a way of inhabiting even the strangest of places. And in doing so, it makes those places themselves come alive, in a bigger way. As any artist knows, it is the small touches that make the larger artwork extraordinary. I was drawn to the pinnacles and cliffs of the desert the first time I saw them. It wasn’t just out of scientific curiosity, or an interest in a landscape different from the one with which I was familiar.

  It was that in many ways, the rocks themselves looked alive. They had colors of their own – yes – but superimposed upon those were abstract patterns and splotches of yellow, orange, green, and gray. And then there were the dripping streaks of brown and black, looking so much like dark chocolate frosting looks as it spills casually off the side of a layer cake.

  In some such places, and when I was alone, I would be still for a moment, let my mind calm, and just take in the view in front of me, without trying to analyze it. Detailed and complicated patterns would appear among the more readily apparent boulders and fractures, turning the scene into a kaleidoscope of colors, shapes, and figures. Jackson Pollock himself couldn’t have displayed more impressive works of art.

  A coating of life is what is responsible for that look – small life creates bigger life, so to speak. Growths of lichens, desert varnish, and moss are the “paints” upon the land. But they are not just “on” the rocks indifferently. They are connected to the rocks – the rocks give them life. Tourists from other climates ask me about the colors and patterns on the formations around the Valley of the Sun. Maybe we take it all for granted, but they notice them right away. I explain that they are living things, and they grow very, very slowly.

  The brightly colored patches and spots that look like “splatter” paintings are lichens. Lichens are actually two life forms living together: algae and fungi. There are many different “species” of lichens; hence there are many different hues and textures. The algal cells are enclosed in masses of fungal filaments, all in compact arrangements that clutch onto barren rock surfaces. The algae conduct photosynthesis and provide the fungi with nutrients, and the fungi provide the algae with protection. Neither could make it on its own in such a harsh environment.

  There is a budding science of lichenometry – the use of lichen growth as an age-dating technique – but it is still in an inexact stage, and there are many factors that influence growth rates. However, in Arizona, when you see a spot of lichen that is, say, several inches in diameter, you can probably assume that it is on the order of a few hundred to a few thousand years old or so.

  Desert varnish (or “rock varnish”, as it is sometimes called) is what we call the dark, surreal staining that cascades down rock cliffs and spires in our area, and it too, takes a long, long time to develop. The varnish is a very thin layer of manganese and iron oxides, together with clay particles.

  But the key to that covering’s existence is a community of tiny bacteria which live on the rock surface, and process the mineral compounds into a protective coating. By sheltering themselves with the minerals, they shield themselves from heat and drying-out, and intense sunlight. The dripping effect (on the landscape) is a result of their having an easier life where water occasionally flows, but desert varnish also coats many rocks just sitting out in the open. They look black and metallic in the sun’s glare.

  Ancient rock art all over the world owes a lot to those little one-celled creatures. Prehistoric humans systematically and artistically pecked through desert varnish on various rock surfaces to produce what we call petroglyphs. The thin, organically-caused patina masks the lighter color in the rock underneath, and it is that showing-through of the rock itself which forms the desired image.

  Moss is a plant that also grows in small communities on rocks, but you don’t see it in too many places in the desert, as it needs more water. Look for it in spots where the sun never shines, and where water can flow periodically. Most of the time it is a dark-gray or black, soft, puffy growth. The time to see it in its glory is right after a good rainfall, when it comes alive again, and is a bright, emerald green in color. It is also much softer to the touch, then.

  All of this life is part of the surface of the rocks. The next story will look at the life inside of the rocks, and, there is plenty of that, too.

Time After Time

June 22nd, 2012


  If you look through some of the various articles I’ve written, you might think I’ve got a slight obsession with time.

  And you’re right.

  I do! Sometimes I think the reason I love geology so much does not have to do with rocks per se. It has to do with time — the concept of deep time. It’s something akin to looking into the night sky high overhead and being enthralled by the great distances to the stars — the depth of space.

  They are so, so far away that even with our best technology today, just getting to the nearest (not counting our sun) star, Proxima Centauri, only a little over 4 light-years distant, would take over 120,000 years!

  The depth of time has that same kind of fascination for me, and, for sure, lots of other geologists. “Deep time” is another name (and, I think, a more appealing one), for “geologic time” — those time-spans of millions and billions of years that are so incomprehensible to all of us.

  I’ve mentioned in previous stories that many of the rock formations encircling Phoenix are very, very old, like those around Squaw Peak aka Piestewa Peak (nearly 1700 million years old). And I’ve talked about others that are quite young — the basalt on Moon Hill, for example (some 15 million years old). So where are the ones that are in-between? What is their story?

  It’s simple. Around the Phoenix area, they just don’t exist anymore. This was something I didn’t really grasp when I first moved here, until I hiked up Camelback Mountain. There are places there where you can walk up and put your finger on a thin line which has replaced those missing rock formations — a line representing essentially all the deep time that elapsed during the time they were deposited, and then eroded away.

  You don’t have to take that heart-pounding jaunt up the Echo Canyon Trail, though, to see that line. Just drive around the west end of the mountain a bit. Or you can even see it from Camelback Road, anywhere from 44th Street to say, 56th Street.

  The west end of the mountain, what some people see as the head and neck of the reclining camel (it must have been the heat that got to him!), is formed of reddish sandstone (and conglomerate — a rock made of mixed sand, gravel, and boulders) layers. They are tilted gently towards the west, and they lie on top of coarse-grained granite, which further to the east of there forms the highest part of the mountain.

  The granite also looks reddish here, but that’s because of a thin coating of rust-colored sand grains, loosened from the rocks above, now covering it.

  The place where the two different rocks contact each other is called an “unconformity” in geology-speak. In other words, there was no direct transition from the formation of the lower rock to the other one above it. In this case, that line of contact represents over a billion and a half years of time — time in which many thousands of feet (probably) of younger rocks were deposited by wind and water over the older granite, and then subsequently eroded away back down to the granite.

  Then, on top of the granite, the younger red sandstone formations we see now were laid down by more wind, water, and maybe some really destructive landslides. These layers of stone are approximately 25 million years old. In my photo, taken along the Echo Canyon Trail on the north side of Camelback Mountain, you can see where the line separates the two rock types.

  It runs from near the center of the picture towards the lower left corner. The sandstone is seen in the vertical face. The lumpy-looking rock below the line, or unconformity, is the very old granite. Here, confusingly, as I mentioned above, both look reddish-orange, due to the dusty coating. Far in the background and across the valley, you can see the McDowell Mountains.

  Any of you who have traveled to our spectacular Grand Canyon may have seen another and famous (but unrelated) unconformity. Down by the river, the flat-lying rock formations that make up all those colorful layers visible in the canyon walls are sitting directly on much, much older rock.

  There, that contact is called the “Great Unconformity”, and it is a classic, textbook example, well-known to generations of geology students from, where else, their textbooks, where it is always prominently discussed.

A Fine Line

May 7th, 2012


  It was late afternoon, with the sun orange and low in the southwestern sky — one of those late December days when the air around Phoenix has sort of a drab look — somewhat dusty, layered, and gray. But it was also the Holiday Season, and I felt a bit like celebrating. I had been looking forward to my drive to this part of the Valley all day, as I hadn’t visited it before.

  Had the main reason for my anticipation been that it was another chance to get out and look at the landscape and rock formations? No, I have to confess. It was the thought of having an ice cold Martini, in the laid-back lounge of the Carefree area’s most elegant resort, that had gotten me going.

  I had just moved to Arizona, and I had read that this particular resort was a place not to be missed. That certainly proved out to be true. Rocks did get in the way that day, however, as they do so frequently in my life. Luckily for me, those interludes always make it interesting. They have a tendency to put things in perspective for me — they separate the little things of everyday life from the things of eternity, or at least the bigger picture, and the longer view.

  I was passing Black Mountain, on its south side. I rolled down the window and tried to get a scent of the cool desert air, but there was none. Being new to Arizona, I only guessed that it must take heat to bring out the smell. The peak loomed high to the left; houses and various structures clinging to its barren slopes, interlaced by tiny roadways that snaked up through stands of tall Saguaro cacti, Palo Verde trees, and Jojoba bushes.

  Not cheap real estate, I figured. It would take a few more dollars in the old savings account before I could put something down on one of those. But the monetary “bottom line” separating me from a life of leisure and afternoons on a deck patio up there somewhere, was not what intrigued me. You guessed it — it was the rocks — and more precisely, a line through the rocks.

  From the south, Black Mountain looks neatly divided in half. The western half is all dark, fragmented rock, and the Saguaros must like it, because there is a thin forest of them there. The other side of the mountain, or its eastern flank, looks like a giant pile of beige rubble. There are fewer of the tall, exotic cacti. Granite boulders abound, and the tan rock is all broken and rounded into picturesque shapes and crags.

  I mentally noted that hiking up that side of the mountain would be a real chore. Making my way on down the road, the division through the rocks stuck with me. I knew right then that I would “get into” the geology behind that granite, which rises above the resort’s lodge, too.

  And that the adventure that afternoon would pay off in more ways than one.

  Why the stark division in those rocks? Why the strong contrast between the two sides of Black Mountain? I knew the hotel’s bar would be the perfect place to ponder those very questions. It did end up taking a little more research, and eventually even a hike up to the summit, to fully grasp it all.

  In other GeoStories™, I have discussed the great antiquity of many of the rock formations around the Valley of the Sun. I’ve also related how the Valley’s mountains themselves, which include Black Mountain, are mostly young — meaning only about 15 or 20 million years old (yes, that’s right, that’s geologically young). They are composed of older rock in much the same way as bricks from old buildings have been recycled and used to create new structures.

  In my GeoStory™, “Missing Time”, I discussed Camelback Mountain, where you can see two formations in contact with each other, the line between them representing a vanished past. In this case, however, on Black Mountain, the line running so neatly up and over its divided summit is a forced contact between two ancient rock types—one literally having intruded into the other.

  On the surface of the world about 1.7 billion years ago, where the places known as Cave Creek and Carefree now lie, sat thick formations of rocks laid down as sediments by vast, ancient river systems. Layers of rock, spewed out of nearby volcanoes, occasionally alternated throughout these. It was the landscape of a continent so old we can only speculate about its outlines. We know, though, that it was moving about the Earth’s surface, as all the continental rocks have done throughout history (and still are doing).

  Along with the movement, and its associated heat and pressure, the rock layers changed their nature a bit (this is called metamorphism). We know them now as slates and phyllites — the geologic names of the rocks of the western part of Black Mountain.

  Throughout the next few hundred million years, with this continental crust literally floating on the more dense, moving, plastic layers below, great crumpling forces caused the Earth to convulse and pulse. The energy drove its crust into long “belts” of distorted rock, that in this case actually stretched over a thousand miles to the northeast.

  This particular period of deformation is called the Mazatzal Orogeny (sounds sexy, doesn’t it?), and during its final throes an extremely hot, fluid body of rock, now described as 1.4 billion year old granite, pushed up and intruded into higher reaches of the older rocks. We see part of that intrusion today, the eastern side of the mountain, on the other side of the line dividing Black Mountain. The two rock formations, and the division between them, exist in other places in the Phoenix area, too, but they’re a little harder to see. They have all been exposed, for us to view now, by recent millions of years of weathering and erosion.

  How nice of those rocks, I thought, for they had once again made my day. That diversion was just what I had needed, and oh, by the way, the Martini was perfect.

Exhilaration & Loathing

April 17th, 2012


  Organic. That’s the word I gravitate towards when I think of the landscape of southern Utah. A myriad of canyons, incised into bands of vermilion, mauve, ivory, ochre and chocolate — rocks from the depths of time in living color.

  It’s a fractal place, if there ever was one. Big gorges branch into smaller gorges. They, in turn, divide into even smaller canyons, subdividing and subdividing, right down to the seemingly microscopic level. Life forms of all sizes cling to those tributaries, however big or small, as those very furrows are the arteries of water, the lifeblood of this high desert plateau. The panorama is rumpled, folded, and convoluted like some kind of living tissue, like a dissected brain of gigantic proportion.

  Just recently, I drove north along one such magnificent artery: White Canyon. There the road skims over surrealistically-shaped Permian sandstone ledges, and I was just beginning a long awaited August vacation. I looked from my speeding vehicle down into the winding chasm I was paralleling, hoping to catch sight of some ancient Anasazi ruin, that (of course) no one had ever noticed before.

  That highway, which runs between the “middle-of-nowhere” towns of Blanding and Hanksville, is among the most inspiring drives I have ever seen. That I could spot some prehistoric cliff structure was not impossible. There are plenty in those canyons. There used to be a lot more.

  I crossed several bridges, looking down into overgrown streams below. Even there, the rich smell of murky stream water in the hot sun reminded me of the life-giving power barely flowing beneath the steel girders. A cobalt sky overhead only accented the scene. Now the road wound up and up, away from the water, through immense vertical cuts in the rock strata, blasted and carved away to oblige the road — as if to enforce upon us all the fact that humans can do anything once they put their minds to it.

  High above the Colorado River, the biggest artery in the plateau, is one of the most expansive viewpoints anywhere. I got out of my car, as I always do at that spot, ready to bask in the vista for a few moments. I walked over to the edge, and looked down.

  Unprepared for what I saw, I gasped (it was only a short one), and then a big, wide smile started to break across my face. I almost started to jump up and down with delight. There you go, boys. Try water-skiing on that. What goes around, comes around.

  Far below, where wakes from motorboats and “personal watercraft” once crisscrossed Lake Powell, lay mudflats. Miles and miles of mud, baking in the sun. I couldn’t believe it. In all my years of driving back and forth across the American West, I had never seen anything like that. I thought again of that idea of “humans being able to engineer anything”. Now, really?

  Do we really think we can just remake Earth’s surface without consequences?

  There is probably no greater symbol of the defacement of the American West than “Lake” Powell — actually a reservoir. It is formed behind Glen Canyon Dam, the concrete wall that stands further downstream in the way of the once relentless Colorado.

  And there is probably no greater insult to a true nineteenth-century American legend, the first explorer of Glen Canyon, than to have his name affixed to what he surely would abhor. John Wesley Powell must be rolling over in his grave, smiling, too, at the cubic miles of mud and silt accumulating in Glen Canyon, and he would probably say to us now, “I told you so”. At least he got to see its splendor. So the symbol is not a mark of progress, after all. It is a symbol of hubris, indeed, even death.

  In my picture, you can see what looks like a long, sloping runway above the mudflats, below the cliff. That is the huge boat launching ramp of the now-closed Hite Marina. Or was the ramp, I should say. The reservoir is almost 100 feet below “full pool”, and therefore lies hundreds of feet from the bottom of that ramp.

  A result of drought in the West, this situation will almost certainly get worse, for the foreseeable future anyway. Combine that with the fact that when you block a river as muddy as the Colorado, lots of silt drops out of suspension, and it starts to build up. All of that grayish sludge you can see now is covering a lost world.

  These realities will render Glen Canyon Dam useless — for either storing water, or for generating electric power. Somehow, people just don’t get it — how fast it is happening here. Those motivated by politics would have us all believe that dismantling the dam is some wacko idea, selfishly promoted by those awful environmentalists. That the aforementioned are so skilled at calculated nuance and misinformation does little to dismiss the facts.

  The Colorado River averages a sediment load of about 100 million tons a year. That’s about 30,000 dump truck loads every day. And as of the time of this writing, the reservoir is dropping about one foot every nine days! The drying-up of the reservoir, coupled with the filling-in by silt, means that it is losing on both fronts: from the top down, and from the bottom up. If you don’t believe me, drive there and look for yourself.

  Beneath that mud and what’s left of the water, are countless archaeological ruins, and the remains of the most intricately beautiful canyon on Earth. By most estimates, present climatic conditions will actually worsen, causing an increase in the rate of the water level’s decline.

  Eventually, the silt accumulation will start to block the dam’s outtake portals, making operation of the power generators unsafe. And by then, even more irreplaceable canyon beauty will be lost to the muck.

  In recent publications, I have written about the modification of Earth’s geology by humans, and how it can be either good or bad. This modification (Glen Canyon Reservoir began filling in 1963), will go down as one of the most calamitous and short-sighted ever.

  If for no other reason, Glen Canyon Dam should be demolished, and what’s left of its reservoir drained, as an admission of our arrogance and conceit in living with nature. Let life return to the landscape.

  If we had real vision, and cared at all about people yet to come into this world, we would leave them something of magnificence and meaning, not the entrenched wasteland that is inevitable under current policy.

A Hard Place

March 17th, 2012

These ancient ruins cling to resistant vertical cliffs, either avoiding something, or in hope of something.

  You’ve all heard it before. You know, the line about how tough things are, the line about an impossible situation, about being “between a rock and a hard place”.

  It was a warm spring day, and I had just about had it with the climb up a steep, brushy, wooded slope, if you want to call it that. It was more like a tangled obstacle course, except that it seemed nearly vertical, and the loose soil beneath my feet made getting up through it even more frustrating, as it was two steps forward, slide back one.

  Annoying little bugs swarmed around my face and ears, but they kept me company and gave me something to yell at. They were the only creatures, I’m sure, that would have thought my sweat- soaked shirt and hat smelled nice. I was beginning to wonder if it was worth it, if all this work made any sense. It would be easier to turn around, and go back to the car, now miles down the deep canyon. My heart was pounding. I was trying to find some ruins.

  I was well into the rugged Sierra Ancha (in Spanish, “wide mountains”), about 75 miles northeast of Phoenix. This remote range is one of the least explored archaeological areas in Arizona, and it is not hard to understand why. Deeply-incised canyons cut through massive layers of rock, and these in turn are coated with all kinds of thick vegetation – tall pine woods at the summit, right on down to the cactus-strewn canyon floors.

  Rattlesnakes abound, and who knows what other dangers, too – maybe the emotional ghosts of those who lived here and built my goal about 700 years ago. Whatever caused people to live in such a place must have been an intensely emotional thing, and I imagine that that emotion was fear.

  And then I saw them. Right above me was one of the most spectacular sets of cliff-dwellings I had ever seen, there literally clinging to the massive rock cliffs above. They looked like they had just grown there, right out of the stone. My mind flashed on the connection between life and rocks, and here was another example. Only here it was humans that grew this place in the rocks, and I knew there were more such spots around that area, too. The rocks offered protection.

  The Sierra Ancha are so rough and craggy because most of the rock there is very hard and tough, and consequently very resistant to erosion. In the area of these Anchan Culture cliff-dwellings, quartzite and limestone are the order of the day.

Massive quartzite in the Sierra Ancha.

  Quartzite is a metamorphic rock, meaning that the original stone has been changed by heat and pressure, in this case altering an old sandstone formation (left-over beach sands, possibly) into a much more durable rock unit.

  Limestone is a rock, also very unyielding, precipitated out of oceanic waters, and forms vertical cliffs in a lot of places where it occurs.

  Both of these rocks point to a time when this part of what we now call Arizona lay along the shores of ancient seas lying to the west and south. It was not North America then, and what we now see as our landscape would then have been around a billion years into the future.

  These rocks are collectively known to geologists as the Apache Group. Higher up in their section, you can also see layers of dark basalt, a volcanic rock that erupted way back then in various places, as the old setting went through some convulsive times.

  Equivalent rock formations are found in and below the bottom of the Grand Canyon, and there they are approximately 5000 feet lower in elevation than they are here, there near the Colorado River itself. Therefore, the rocks above that point, most all of those colorful layers now seen in the walls of the Grand Canyon, were once on top of the Sierra Ancha as well.

  Because of massive uplift of the region, the younger rocks are now gone, and the innards are exposed.

  You can see these same rocks when you wind your way up State Route 288 (also known as the Young Road) from the valley floor, near the Salt River and Roosevelt Lake, to the upper reaches of the Sierra Ancha, near Aztec Peak, on the way to the small town of Young. In this stretch, you are going up through time.

The Sierra Ancha, along the left skyline, appear deceptively gentle. Roosevelt Lake is in the foreground.

  My distress at the sweaty work-out turned to delight; my desperation turned to awe. Tough places, tough rocks, I mused. The Apache Group is still there because it is so hard to get at, and in turn, the dwellings of the ancients remain tucked within its depths, mostly untouched, for the same reason.

  That the inhabitants of these ruins chose to live, and die, between the difficulties of the nearly impassible terrain below and the sheer walls of stone, demonstrates the incredibly fine line of life to which they clung, and the tenacity of nature itself.

Name that Tune

February 9th, 2012

  I moved to Phoenix about thirteen years ago, and as I drove around a bit back then and started learning my way around town, I took note of the various landforms surrounding us. I couldn’t quite put my finger on why, but South Mountain looked distinct to me — different from and more rounded than the other mountains that stick out of the relentless grid of asphalt and concrete that stretches on and on through the Valley of the Sun.

  I started looking into the reason, and one of the things I soon found out is that the rugged barrier at the south end of Central Avenue is correctly called the South Mountains (note the “s”). Where all the TV towers stand, and what most people refer to as “South Mountain”, is more properly named the Main Ridge. Looking south from the downtown area of Phoenix, you can also see a separate, smaller high point on the west end (right) of that rise. Its correct name is the Alta Ridge. Much lower, in front of it, and just next to the small town of Laveen, is the North Ridge.

  Speaking of names, the Pima Indian (Akimel O’odham) name for this set of peaks is “Muhadag Du’ag”, or “Greasy Mountain” — a take-off on the dark sheen of the rocks there, caused by a surface coloration known as “desert varnish”. If we really wanted to honor Native Americans, especially those who actually lived in the Valley, we would return its name to what they called it. We could have applied this line of thinking to certain other mountains around Phoenix as well, but I’ll save that discussion for another time.

  More often than not, like everyone else in town, I also call this aggregate of lumps South Mountain. The big point here is the way it looks -a long, low dome-shaped rampart. There is one simple reason for that: the rocks of South Mountain were pushed up, basically through the crust of the Earth. Most of the other ranges around us traverse central Arizona for the opposite reason: the landscape is being pulled apart on a massive scale. They are left standing as evidence of that strain as the valleys between them, like our own, drop away slowly, surely over time. Gravity never sleeps.

  South Mountain is what is called in geology-speak a Metamorphic Core Complex, and I’ll spare you some of the technical details. That term, which from now on in this article I’ll refer to as “MCC”, is a great name to throw around at cocktail parties, and one to remember if you are ever to be on one of those TV “Question & Answer” shows with big prize money. There is a whole, albeit small, subset of humanity out there that seems to be fascinated by them, and they’re not just geologists.

  Don’t ask me why, but one time, on a whim, I typed the term into a music-sharing website, and was amazed that a song actually came up with that name. Somebody (artist unknown) had in fact named a song to honor one! I downloaded it immediately, of course, certain the musician would not have minded. It is a spacey-sounding instrumental (naturally, and gladly) — I am not sure what kind of lyrics you could put to the subject of plate tectonics.

  There is “belt” of MCC’s across western North America, running from British Columbia down into Mexico. They run right through central Arizona, and South Mountain is one of the best of them. They are thought to represent an early phase of the “pulling apart” of North America. Around 25 million years ago, the crust started to stretch in a northeast to southwest direction. As it did so, it thinned out, and lighter rocks, which were once more deeply situated, basically “bobbed up” (the pushing-up I mentioned above) as sort of dome-shaped wrinkles — the South Mountains are one such dome.

  Then, millions of years later, the crust actually started to fracture and break apart. As you might expect, the resulting cracks — called faults — run perpendicular to the orientation of the stretching. This force, then, gave us the big valleys we inhabit, and left in-between massive blocks of rock standing — these are the mountains (Camelback Mountain and Squaw / Piestewa Peak, for example) around that have weathered into jagged summits with a character unlike that of South Mountain.

  I am continually perplexed by the number of Phoenicians who have told me they’ve never been up onto the South Mountains! There is no better view of the Valley than what you can get from Dobbins Lookout (the most popular spot). When you go that viewpoint, look just to the east, at the canyon wall just below you. There you will see the rocks all stretched out, horizontally, with very gentle curves from side to side — visible testimony of the doming forces that created the South Mountains MCC (see photo). Once you see that evidence, you will notice the same rock fabric everywhere around in those peaks.

  For more on MCC’s, look at a string of six photos beginning with a view of Central Phoenix from South Mountain. The fifth view in the sequence is a view from the Space Shuttle Atlantis, looking directly down onto the subject of someone’s favorite song.


January 8th, 2012

Ancient petroglyphs decorate a basalt boulder at the Deer Valley Rock Art Center in Phoenix, Arizona.

  Take take a look at the boulder in the picture above. You will notice that it is literally covered with markings and drawings. We call these “petroglyphs”, and they were created by pecking through the layer of desert varnish that coats many rocks in arid climates (as opposed to “pictographs”, which are painted onto rocks). Research has shown that petroglyphs in central Arizona were created between about 10,000 and 700 years ago, by peoples we now refer to as Paleo-Indian, Archaic, and Hohokam.

  But, as those of you who read my GeoStories know by now, there is more than that about them that would interest me. What really arouses my curiosity is why they are there.

  They are found in various places around the Valley of the Sun. But why in one place and not another? There are plenty of rock faces and walls scattered around our area. Some have no markings, and others, like the boulders at the Deer Valley Rock Art Center, just off I-17, north of Phoenix, have hundreds or more. Operated by Arizona State University’s Department of Anthropology, this place alone preserves over 1500 such works of art.

  Here, a trail approximately .25 mile long, leads along the base of outcrops of Tertiary age basalt on the edge of the Hedgpeth Hills. This is some of the youngest rock in our area — only about 15 million years old.

  I first visited this place on a beautiful, warm, autumn day, and it seemed that I had it all to myself. The sweet, dry smell of the desert surrounded me with comfort. I was walking along this peaceful trail, looking up at the cascade of dark rocks from above, when I was startled by an abrupt, booming voice from the chaparral around.

  “Hello, sir! May I be of help to you?”

  Totally surprised, I quickly turned around, and saw a man wearing a ranger’s uniform coming towards me from out of the bushes. He was Native American, or Indian (which is the designation he later told me he preferred), stocky, strong looking, with graying hair and chiseled features, and somehow he just “beamed”.

  He introduced himself, and I could see he was “official” by the badge on his uniform.

  In a very amiable manner, he immediately started dispensing information about the Rock Art Center, its history, and of course, the petroglyphs. But I was still trying to figure out why I had not seen him at first, how I had missed noticing him as I walked along that trail. After all, the chaparral there is not that thick or tall. And it seemed that he just “didn’t fit”; as if he had just materialized on the spot. I even had the thought that he was just posing as a ranger! I liked him at once.

  We stood in or near that same place for quite some time, talking about all sorts of things — his background, American Indians, history, artwork on stone that he produces on the side — it was fascinating. I never even made it to the end of the trail! I had to leave, as it was getting late, and I had another appointment. I apologized for having to end our enlightening conversation.

  Then one thing occurred to me strongly. I felt that I had finally met someone who really knew what the petroglyphs there, and elsewhere, were really about. I mean, what were those Indians really up to with all these drawings? I know, I’ve read all the ideas posited by present-day researchers about the markings being religious art, communication symbols, or maybe just plain graffiti.

  But why, in places like this? Why, in some places and not others? What was it about this rubbly, remote (in ancient times), harsh location that inspired people for thousands of years to spend a huge amount of energy creating all these drawings?

  Finally, here was someone who knew.

  So, before turning back along the trail, I explained to my guide my quandary. Those of you familiar with my other writings know where I am going with this: what is it about the rocks that energized the ancients here?

  “I am searching for that answer,” I pleaded, “and maybe you, being a knowledgeable Indian, and an artist, can tell me.”

  His answer was, to say the least, totally unexpected, and it came without hesitation: “Perhaps, sir, what you are really searching for is your own spirituality.”


  If you want to do some “searching” along your own path, this is one place to begin. Go out there, and see what you feel in this special place. Take the Deer Valley Road Exit off I-17, and follow the signs, going west for several miles. The Center is closed on Mondays, and hours during the rest of the week vary with the season and day. You can get more information by calling 623-582-8007.

Gold Dust

December 10th, 2011

The classic view of Superstition Mountain, from the Lost Dutchman State Park, Arizona.

  Let’s talk about gold. Not just any gold, but lost gold. If there’s one thing more appealing than found gold, it’s lost gold. Because that means that the gold – maybe an unknown, vast quantity of it – is still out there somewhere, just waiting to be found. Like fairy-dust sprinkled from a magic wand to vitalize some situation, a dusting of the lure of gold can make a place attract people – those people looking to make it big.

  Sometimes they win; sometimes they lose.

  And sometimes they die.

  We have our own place of temptation right here in our backyard: the Superstition Mountains. For the past century or more, this rugged range of desolate, inhospitable, and yet beautiful rock formations just to the east of Phoenix has drawn countless treasure seekers. The goal? A mysterious cache of gold, or gold ore, or maybe even a mine itself. Who knows which? That’s part of the mystery, and the draw of the place.

  In 1891, one Jacob Waltz, a German immigrant and prospector, known locally as the “Dutchman” (men from both the Netherlands and Germany were then frequently called that in America), died in the Phoenix home of a friend, Julia Thomas. On his deathbed, Waltz described to her the location of a gold deposit of which he knew, deep in the Superstition Mountains. But in his possession then were only a few gold nuggets, and he never had appeared to be a wealthy man.

  Yet, Ms. Thomas and two of her friends, the Petrasch brothers, believed that there was something to his story, and they set out to find it. They spent weeks roaming the wilderness, searching for whatever they could find, which ended up being nothing. Julia Thomas did find a way to capitalize on the Dutchman’s fate, however. She drew up and sold some “treasure maps”, as well as told Waltz’s story to at least one freelance writer, who in turn embellished it even further.

  Hence, the story grew, and multiplied. And so today, there are almost too many “Lost Dutchman” stories of which to keep track. (And remember, it is the gold that was lost, not the Dutchman.)

  There are variations which include Mexican miners (who supposedly originally found the gold), Apache Indian raiders (who killed the Mexicans and maybe even Waltz’s sometime mining partner, Jacob Wiser), high-graded gold ore stolen by Waltz himself from near Wickenburg and stashed in the Superstitions, and even Jacob Waltz having murdered his partner to hoard the gold for himself.

  The wildness of the terrain, the relentless, blazing sun and lack of shade, the dearth of water in the remote desert canyons of the Superstitions, and a colorful cast of crazies, desperadoes, and dream-seekers who have over the years spent countless time seeking out the rumored riches have only added to the luster of the story.

  The details of all these legends and maps do not matter so much as the fact that they exist, and that the story of the lost gold endures – the fascination goes on. Over the years more than two dozen adventurers have lost their lives, in one way or another, while exploring the range.

Looking deep into the heart of the Superstition Wilderness, near Phoenix, Arizona. Weaver's Needle is in the background.

  The derivation of the name “Superstition” is not even certain. One version is that in the 1500’s, the Spanish explorer Francisco Vasquez de Coronado apparently gave the mountains that name, based on the Apaches’ claim that therein lay the abode of spirits, ones who did not look kindly upon intrusion, especially in the name of profit.

  Only a few years after Jacob Waltz’s passing, hard-rock gold was discovered not far from the north side of the range, near what is now the little mining town of Goldfield. Millions of dollars were taken from the ground during the heyday of mining operations there.

  That a true in-situ gold deposit does exist in the Superstitions themselves is very unlikely. As I’ve mentioned in the past, the range (in this case, the western end, of which is to where the legends refer) is built-up of thousands of feet of ancient volcanic ash, fused into thick, resistant layers which today have eroded into a maze of pinnacles, ridges, and gorges. Barren volcanic cinders – now rock – and that’s all. Barren of precious gold, that is, but not of dreams.

A maze of golden canyons makes travel through the Superstitions a true adventure. This view is from along the Apache Trail, aka State Route 88.

  Take a look at the Superstition Mountains from a distance, in the setting sun sometime. If you give pause for a moment, they look yellow, even golden. It’s that would-be coating of gold dust out there that you see.

  That and the glimmer in your eyes.