Facets of the Natural World around Us ....
October 9th, 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 gemland.net), 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.
Read Part 1 of this GeoStory, at “Top Coat“, in GEMLAND.NET.
You can print this, the last part of the GeoStory ™, which is included in the whole PDF document for FREE (for NON-COMMERCIAL USE ONLY).
September 7th, 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 GeoStory will look at the life inside of the rocks, and, there is plenty of that, too.
Read Part 2 of this GeoStory, at “Under Coat“, in GEMLAND.NET.
You can print this, the first part of the GeoStory ™”, which is included in the whole PDF document for FREE (for NON-COMMERCIAL USE ONLY).
August 11th, 2012
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.
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.
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.
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July 17th, 2012
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.
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.
Author’s note: To learn more about “weirdly-shaped rocks” and the rest of the Phoenix area’s engaging geology, visit www.gemland.com.
You can print this GeoStory ™ out as a PDF document for FREE (for NON-COMMERCIAL USE ONLY).