Posts Tagged ‘Metamorphic’

Topcoat

Sunday, 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.

A Fine Line

Monday, 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.

A Hard Place

Saturday, 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

Thursday, 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.

What’s the Angle?

Wednesday, June 15th, 2011

Tilted rocks in Papago Park, in Phoenix, Arizona.

  Weirdly-shaped rocks. I’ve heard that phrase over and over again, mostly from tourists. Wondering why the rocks look like they do, those visiting the Valley of the Sun notice them immediately, as those formations are almost right next to the airport where the visitors have just arrived.

  The pinnacles stuck in my mind, too, on my first visit to Phoenix, many years ago. Brightly orange in the setting sunlight, there was something about their curvy, pointed look, all filled with voids and cavities: they seemed like frozen flames rising from the flat desert floor.

  The Papago Buttes, we call them. They are the centerpiece of Papago Park, one of the City’s thoughtfully planned expanses of preservation in what otherwise surely would be yet more endlessly repetitive housing tracts, strip malls, and asphalt checkerboard development.

  What people first notice about the buttes are the caves and the holes in the rock. In geology-speak, those are called “tifoni”. I looked up that word, and it means “typhoons” in Italian. I’m not sure why or how those storms made it into the lexicon of geology, let alone in Italian, but maybe that’s a subject for another day.

  As for the openings themselves, they are caused by differential weathering and breaking-down of the host sandstone and conglomerate (which is a rock composed of different-sized stones and particles, sometimes called “puddingstone”).

  But there is more here of which to speak. The structure of the buttes, or the way in which they connect to the rocks underneath, is one of the more interesting facets of the geology here.

  In other writings, I’ve previously described to you the nature of the rock surface underlying our valley — an amazingly deep, rugged trench in the Earth’s crust. The buttes are just the tips of some craggy peaks that are almost completely buried by the sand, gravel, and salt beds that fill the valley and give its floor such a flat appearance. They poke through the surface in Papago Park just enough to make a great backdrop for the Phoenix Zoo, and the Desert Botanical Garden.

  Drive along Galvin Parkway near the Zoo, or better yet, take a walk around the Hole-in-the-Rock area in Papago Park and look over at the prominent tall butte, just to the northwest. You will notice there, I hope, that the reddish sandstone and conglomerate is layered, and that the layers are slanted steeply to the southwest.

  Recall also, that I told you about the South Mountain Metamorphic Core Complex (I just love that phrase — it’s got such an academically-sounding, yet melodic, ring to it.) in my previous essay, “Name That Tune”.

  I explained there how the broad, arching dome of South Mountain was pushed up from the heated, plastic rock of our planet’s crust around 25 million years ago. Though the rock was hot and soft down deep, it had to push through higher layers that were cool and rigid. Some of those layers are the orange rocks that make up the Papago Buttes.

  Rigid rocks don’t bend, of course. They break. And when they broke, in this case, they had to “get out of the way” of the emerging dome, part of which we see now as South Mountain. In making way for that uprising mass, they couldn’t just simply slide out sideways, as they were confined by other rocks in the same layer, and rocks behind, above, and below those.

  You might be thinking that South Mountain is quite a distance from Papago Park, so why the problem? Geologically, of course, it is not. And at depth, down there below the fill material in the valley, their rocks are physically connected. When the rock layers broke from the pressure below, they could only break up into fragmentary pieces or slabs, looking something like how a deck of playing cards looks when it is unevenly pushed from the side, splaying the cards into a skewed stack.

The Papago Buttes, with Camelback Mountain in the background, highlight the Phoenix Zoo's Lake, in this view.

  Now imagine those cards as the rock slabs, first breaking into pieces, then standing up, while tilting back and away from the imposing mass coming up from below. That’s what you see at the Papago Buttes, and in my accompanying picture. The tilt can even be seen at Tempe Butte, next to Sun Devil Stadium, even though that is a different type of rock. All of the rock layers are tilting away from South Mountain.

  Theoretically, other rock layers hidden beneath us also tilt away from South Mountain, making it the center of a giant bullseye, of sorts. Those inclined layers strangely reveal one more chapter of the ongoing story written in the rocks all around us.

Geology Upside Down

Monday, May 9th, 2011

Four Peaks,on the skyline east of Phoenix, Arizona.

  Dominating the skyline east of Phoenix and Scottsdale, Four Peaks is one of the most recognizable of central Arizona’s mountains. Locals consider it to be one mountain, so I won’t say “Four Peaks are …”. It’s one of Arizona’s landmarks for which little pondering is required as to how it got it’s name! (In the photo above, Four Peaks is in the distance behind the closer Goldfield Mountains.)

  Geologically, it is a piece of landscape art, and the way it formed is almost counterintuitive. You might think that the four summits we see so easily are big piles of rock that were molded into shape on top of the older, lower slopes. But that would be wrong! The rocks of those four summits were there first. Then the granite below was added.

  How, you might ask, could that be? Well, the makeup of the Earth’s crust is a complicated thing, and is not always what it seems. Geologic time, and the forces that have moved things around throughout the history of the world, always seem to combine to give us an interesting story.

  If you drive out the Beeline Highway (SR87), by the time you are about 15 miles from Fountain Hills you will be near Milepost 200, and you will be looking at Four Peaks on your right (east). Even better, go to near Milepost 204 and turn onto the gravel road marked “Four Peaks”, and you can get a few miles closer. You’ll be able to see that the mountain is basically made of two rock formations. One is a continuation of the bedrock you may be standing on: granite. The other forms all four of the peaks. The dividing line between these rocks is more or less where the slope breaks, just below the notches between the peaks.

  About 1700 million years ago, during what we now call Precambrian time, our area lay on the edge of an old continent — an area probably much like today’s Gulf Coast near New Orleans. All of the sand and muck that came down the big rivers from the interior got dumped into a big basin, like the present-day Gulf of Mexico. There it piled up, got buried, eventually hardened, and was baked into thick, resistant layer or slab — very hard rock we call quartzite.

  Several hundred million years later (not really a long time in geologic terms) the immense forces that constantly reshape the Earth’s surface crumpled the land and its many rock formations from side to side, pushing up great mountain ranges that actually extended all the way over to where today’s Great Lakes are. Geologists give this little event a nicely sensual name — the Mazatzal Orogeny.

  During all of that pushing and shoving a lot of the rock below was very hot. Molten granite, in fact, and here’s where the art work comes in. For whatever reason, in the area of the future Verde River Valley, the underside of the above-mentioned quartzite slab was very unevenly shaped. Maybe it started out that way; maybe it got shaped by the pushing action of the molten rock, pulsing up from below. The result, in any case, was that monstrous chunks of the quartzite now hung down into the granite. Four of them.

  Granite erodes away more easily than quartzite. It breaks down into crumbly rock grains, some of which those of us who hate mowing lawns use for landscaping around Phoenix. So the granite around the four big masses of rock slowly wore away, down, down, into rolling hills and slopes and surrealistically shaped boulders that make the Beeline such a scenic drive.

  The four big peaks towering above the trip to Payson even have a geologically technical name: roof pendants — remnants of a much more vast layer of quartzite; a layer of one-time mud and beach sands and sea-side days gone by.

4 Peaks Amethyst gemstone  These big pendants give rise to little pendants — sparkling, beautiful little pendants in the form of the vivid purple gemstones we call Amethyst, mounted into jewelry (yes, not only pendants, but ring stones, earrings, and all other wearable forms).

  You see, up there on southernmost of those peaks, is one of Arizona’s (and America’s) treasures: the Four Peaks Amethyst Mine. Deep inside the quartzite, and way in the past, networks of fractures formed where quartz-rich solutions grew beautiful quartz crystals.

  Quartz is a mineral composed of silicon and oxygen, and the purple variety is called Amethyst. The crystals are now mined and cut into gems, which in this case are considered to be within the world’s finest grade of amethyst.

  You can even wear one — a little pendant cut from a very big one!

 Author’s note: Besides being very inaccessible, the Four Peaks Amethyst Mine is on private property and is completely closed to the public.

First Impressions

Saturday, February 12th, 2011

Desolate hills like these give you room to think, or NOT to think.

  It was a crisp autumn day, and I had just crossed over a narrow divide into a broad empty canyon in the White Tank Mountains, just west of town. Until then, that morning, it had all been mostly uphill, and I could finally just “coast” now for a while, even though I was only about halfway through my hike.

  Still mildly sweating, and with slow, steady breath returning, I stood there in the glaring sun, just gazing into the desolate solitude ahead of me. It was empty, and silent. I just had to get out my camera, and take a photo of the lonely magnificence. There was something about that perspective, indeed the very presence within those barren rocks, that could not be denied.

  Look at my picture here. You might ask yourself, “so what’s there here to see?” “It’s just some hills and lots of cactus. There’s nothing there!”

  Precisely. It was one of those “you had to be there” moments, and yet, it was intimately tied to that place, too (and still is). There is an appeal to such views, and it doesn’t happen everywhere. It has to do with the lay of the land, the look of the rocks, in fact their very makeup.

  I’ve talked about this kind of thing before. I mentioned that in Western thought (and science) we give little or no importance to subtleties and feelings. Most other geologists I know would see in that hollow only metamorphic rocks, classified as Precambrian age (around 1.7 billion year old), and a much younger granite, judged to be about 70 million years old (both of these rock formations really are what is there). They would also see nothing of economic value, hence making the place “worthless”.

  But mix a little Zen into the Earth Sciences, and you have a different way of classifying things. According to Oriental wisdom, “every stone has a face.” Every rock looks best when viewed in a certain way, from a specific angle. I would have to agree, and on a large scale it is what makes particular mountains look so appealing, and gives them character.

  I think of that valley and the impression it created in me often. I look at its picture sometimes just to remind myself of how I felt then, how momentarily unburdened of all the clutter in my mind I had been. When I first saw the panorama, the instantaneous perception of that scene was like walking into a dark room, pushing the light switch to “On”, only to have the light instantly “pop” with the flash of a bulb just burning out.

  Think back — you’ve had that experience. Remember how you can visualize the room for a few moments, before the image fades from your brain (and before you run to replace the light bulb)? In the instant the view unfolds, you have the briefest chance to experience the scene without thinking about it. And then you may see aspects you would otherwise never notice.

  There is a Japanese art form known as Suiseki (literally “water stone”), in which natural rocks or stones, in this case small enough to be easily carried around, are valued for their aesthetic appeal. The characteristics that make them so desirable are a combination of suggestiveness, subdued color, balance, and four other aesthetic qualities for which we in the Western world have no precise words: wabi, sabi, shibui, and yugen. These words connote a mental state, felt by the observer.

  “Wabi” translates roughly as a mood of melancholy, loneliness, desolation, stillness, and unpretentiousness. The object evokes a subjective feeling. “Sabi” means ancient, mellowed, seasoned, or mature. “Shibui” connotes quiet, elegant, under-statedness, even refined. And “yugen” can imply obscurity, mystery, the profound, and the subtle, much in the way the moon shines out from behind a pattern of clouds, or a mountainside shows through a layer of thin fog.

  It is not without merit to say that rock formations, hills and valleys, even mountains can display equivalent indescribable characteristics. You may have noticed such feelings yourself somewhere in the great outdoors. You’ve just never thought about them later. You see such feelings expressed in the works of certain landscape painters, especially impressionist artists.

  Walk through some galleries in Scottsdale and take a close look at what various artists are trying to convey. I often wish that I was a painter, and fancy that if I could only master the strokes of brushes and thick oils on canvas, I would go back to the White Tanks, or seek out other such spots, and spend my time trying to capture the essence of landscape.

  The nature of that landscape is in the rocks as much as in anything else out there — maybe more so. Their age, their presence, is something that controls one’s mind and sets one’s mood.

  As with meeting someone new, it’s all in the first impression.
 

*******

  For more on this subject, go to www.gemland.com, click on “GeoArt”, and visit the Japanese Friendship Garden in downtown Phoenix. The whole park is constructed with these concepts in mind.

  Also visit the “GeoScenery” section, by going to the map called
“The Rocks of the Valley of the Sun”, and look at the sequence of views in the White Tank Mountains. If you want to shift back to Western sensibilities you can do that, too, and indulge yourself with geologic explanations galore.

  And then, even better, go visit the Japanese Friendship Garden in person!

Time is on my Side

Wednesday, November 3rd, 2010

Ferruginous quartzite (dark rocks) in Phoenix Mountains, Phoenix, Arizona.

  When I was young, growing up on the brown, flat Cretaceous rocks of central Montana, I used to fantasize about dinosaurs. It’s what got me into geology in the beginning, I guess. I was taken by the idea that where they roamed was right there, in the same physical space I was in at the time. Just about eighty million years earlier is all. Maybe a Tyrannosaurus Rex had actually walked across the ground occupied by my bedroom!

  People tend to visualize scenes from the distant past as though they were necessarily somewhere else. In space, I mean. But there were alien landscapes right here, just not now. This idea is conveyed in H.G. Wells‘ classic novel “The Time Machine”, now recently made (actually remade) into a movie.

  The movie does horrible justice to the original story, but you get the idea by watching the Time Traveler in his machine, sitting in one spot, with the “hours-days-years” odometer rolling on in a blur. He starts the machine and his journey through time in his laboratory in London. At one point (in the book) he “lands” in a rhododendron garden looking over the River Thames, surrounded by alien structures; in another scene he is on a barren beach in the distant future, watching a dying red sun setting into a future ocean of dead, spent waters. All those scenes occur in the same place.

  Back to Phoenix and now, in which the landscape is far different from way back then, let’s say, in Precambrian time, for example. Take a drive on SR 51, the Piestewa Freeway, where it cuts through the Phoenix Mountains, just to the northwest of Squaw Peak, and you will see what I mean.

  If you are going north, look off to the west (left) just after you have passed the Northern Avenue Exit; if you are going south start looking west (right) about the time you get to the Exit ramp. If you like to walk, you can park in the Dreamy Draw area, and approach this area from one of the trails in the Phoenix Mountains Preserve, a city park.

  About half a mile away, up on the east slopes of those rugged rocky peaks you will see dark brown, almost black areas of broken up rocks and rubble. Some of this rock forms a pointed outcrop just at the south end of that set of hills, and is also visible elsewhere in the Park. There are a few houses (with great views of the Valley, to be sure) to the north of these rocks, near a saddle.

  What you are looking at are the remains of ancient, submarine hot springs — very ancient, and very submarine, from the bottom of an ancient ocean. These rocks have the wonderfully technical name of “ferruginous quartzites” and the hot springs that formed them erupted, seethed, and bubbled about 1700 million years ago, at the bottom of a vast sea whose only occupants were life forms so primitive that you would have needed a microscope to get their names. The hot springs were rich in iron, and those iron minerals give the rocks their current color.

  The Phoenix Mountains are made of a section of the earlier crust of Earth where the rocks were formed in an environment somewhat like that off the coast of present day Japan. If you were to walk from the freeway in Dreamy Draw over to Shaw Butte (about 4 miles), you would be going right down through rock section (now standing on end, basically), that shows the whole evolution of that environment. If you were going to strap yourself into Wells’ Time Machine, and dial up, say, April 10, 1,700,000,000 BC, you had better already be wearing your deep-diving equipment!

  Our planet’s crust is in constant motion. The shapes of the land masses we know today are as ephemeral as the shapes of clouds in the sky. The continents move about relentlessly, literally floating on top of more dense fluid rock below. Heat from deep within the Earth sets huge convection currents into motion, causing continental rocks above to glide about, sometimes crashing and fusing together, sometimes splitting into new shapes, all of it happening all of the time, just in too slow of a fashion for us to grasp easily.

  Our journey through time would take us to the edge of one of these land masses, where heat from the gargantuan convection cell below has broken through, boiling the waters, and creating a primordial soup in which early life prospers.