Saturday, May 24, 2014

To See a World in a Grain of Sand

To see a world in a grain of sand,
  And a heaven in a wild flower,
Hold infinity in the palm of your hand,
  And eternity in an hour.

- William Blake, Auguries of Innocence

This weekend I went camping at Perdido Key, a barrier island straddling the Alabama/Florida border. The eastern end of the key is part of Gulf Islands National Seashore, so it's blessedly free of condominiums and crowds. If you walk at least a mile from the last parking spots, you can pitch a tent and sleep right on the beach. It's pretty glorious. The tourist brochures say the beaches there are some of the whitest in the world, and I believe them. It almost looks like snow.

Sitting on that beach made me think of William Blake's poem. Could he have been on a beach when those lines came to him? I imagined him standing there, listening to the waves, letting a handful of sand run through his fingers, and thinking, "To see a world in a grain of sand....that's got a jolly good ring to it!" OK, it probably didn't happen that way, but it's easy to see how such thoughts could occur to someone standing alone on a beach. Something about the seashore skews your perceptions. Time moves in funny ways. You watch the waves rolling in rhythmically... unceasingly...and you do feel like you can glimpse eternity in an hour. There's a sense that the waves have been rolling in forever. And, by human standards, they pretty much have. They were crashing on shorelines when the earth was still raw and lifeless, and they have been ever since.

Of course, William Blake probably wasn't thinking in terms of geologic time. In his day, scientists were just starting to realize how ancient the earth really is. Besides, he had an uneasy relationship with science. He hated the thought that a narrow scientific view of the world would usurp other ways of knowing, and expressed those worries in these famous lines:
May God us keep
From single vision, and Newton's sleep.
Blake believed there were some things science would never capture, and I think he was right. But I also think he was wrong to be so suspicious of Newton's approach. Blake talked about opening "the doors of perception" And he did, with his poetry and art. That's one approach, and an essential one. But science is essential, too. It can also expand our vision. Science reveals that Blake was right in ways he may not have realized. You really can see a world in a grain of sand, and science offers one way to see it.

Consider the white sand grains that form the beaches at Perdido Key. When I went there this weekend, I didn't know much about the geology of beaches, so I had a shallow, impoverished sense of the place, at least intellectually speaking. All I could do was think: Here's a beach, and it sure does have some white sand. Gosh.

I didn't know why the sand is so white, or how the beach got there. Did it form from bedrock somewhere down below, or did it come from somewhere else? What's it made of? Coral? Limestone? I didn't know. Now that I've learned something about it, my view of the place is both broader and deeper. I can connect the sand grains on that beach to epic tectonic processes that shaped the face of the entire earth. Even more epic are the timescales involved, in which mountain ranges rise and slowly crumble...and then rise and crumble again. Those are the worlds I can now see in those grains of sand, and all I had to do was some reading.

Sands of Time

So, where did that sand come from? Let's start on smaller scales, and work up to the epic ones. The sand at Perdido Key, and all along that part of the Gulf Coast, originated as quartz grains in rocks hundreds of miles away, in the Appalachian foothills of northern Georgia. As the rocks eroded, sand washed down the Chattahoochee and Flint rivers to the Apalachicola River, which enters the Gulf about 180 miles east of Perdido Key. Longshore currents in that part of the Florida Panhandle flow from east to west, so the sand has washed eastward all the way to Alabama.

The sand is white because it's almost pure quartz. Quartz is common in sand around the world, but it's usually mixed with other minerals from its parent rock. Those minerals aren't as tough as quartz (few things are) so they break down, leaving just the quartz grains behind. The Apalachicola River hasn't brought fresh sand all the way to the Gulf for several thousand years (because of glaciers and changing sea levels, but I'm not getting into all that here.) The sand in the area has been churned by waves until all the grains besides quartz (and some coral and shell fragments) have been ground to silt and washed out to sea.

Now let's expand the world of those sand grains a little more. Why was all that quartz in the north Georgia hills in the first place? The answer takes us much farther back in geologic history, and requires a wider, more global perspective. The quartz was first formed when two tectonic plates crashed together.When that happens, one of them is forced under the other, and plunges into the earth. The heat and pressure down there cause it to melt into magma, which then starts to rise back toward the surface. Most quartz is formed in magma that doesn't make it all the way up. It cools slowly underground, allowing various minerals to form large crystals, which interlock together to form igneous rocks; usually granite.

Quartz lasts a very long time, so a piece of it in an igneous rock may be starting a journey through a whole sequence of different rocks and environments. For example, a bit of quartz might form in granite deep underground, then be lifted by tectonic processes as part of a mountain range. The heat and pressure may turn the granite into a metamorphic rock like gneiss, but the quartz will still be there. As soon as the mountain range starts forming, it starts weathering away. Now our piece of quartz weathers out of the mountain rocks and is washed down a river to the coast, where it joins countless other grains of sand deposited on the beach and seafloor. But that's not the end of the story. All that sand can eventually turn into sandstone, which may reenter the rock cycle. Tectonic collisions can into another mountain range, where it may remain relatively unchanged, or it may be pressure-cooked into metamorphic rock like quartzite. Either way, if it's near the surface in those mountains, it will eventually weather out and head for the sea again. Some quartz grains have passed through multiple cycles like this. Quartz is tough stuff.

The ancient igneous and metamorphic rocks of northern Georgia have just this kind of story. Some of the metamorphic rocks there can be traced back over a billion years. That's when they formed from earlier sedimentary rock (made of sediment some earlier, forgotten highlands.) They were metamorphosed when the edge of what would become North America collided with another continent, suturing the two together in a mountain range in an event called the Grenville Orogeny. New rock formed as magma rose toward the surface and froze into great granite structures called plutons. Stone Mountain, outside of Atlanta, is the top of a pluton, though it's a younger one.

Around 700 million years ago, the continent started to tear apart, and the rift turned into the Iapetus Ocean (the Atlantic Ocean was named after Atlas. In Greek myth Iapetus was Atlas's father.) Iapetus lasted about two hundred million years, and then closed again, as the continents coalesced into the supercontinent Pangaea. Their slow-but-mighty collisions resulting in a series of mountain-building events which created the ancestral Appalachian mountains, as well as mountains as far away as Scotland and Morocco.

Pangaea had a good long run, but it began to break up about 175 million years ago. North America went out on its own as the Atlantic Ocean began to form. The ancestral Appalachians eroded into a flat plain, leaving only their hard rock roots below the surface. Finally, just a few million years ago, the area was uplifted again. Rivers cut deeper into the ancient rocks in the Appalachians and Piedmont, and began carrying more sand from those rocks toward the coasts.

The sediments that form the area around Perdido Key are all less than 3 million years old (a mere 30,000 centuries), but they're composed of particles of rocks far more ancient than that; ancient enough to have seen oceans and mountain ranges come and go.

Many Worlds

That's the kind of vast and ancient world science can show us in a grain of sand. Science allows us to see beyond the surface of nature and get a glimpse of its true breadth and depth. It doesn't subtract from the beauty of nature, or art, or poetry. It enlarges it. It only subtracts if we forget there are other ways of engaging with the world, and see it in exclusively scientific terms. The trick (and I admit it can be tricky) is to avoid any kind of "single vision," including William Blake's, and leave your mind open enough to see the world in multiple ways at the same time.

But not, as they saying goes, so open that your brains fall out. Not any point of view is valid. If you believe mermaids exist in the physical world, and not just in myth and literature, science is going to disappoint you. Mythology shouldn't be mistaken for science, and vice versa, any more than a hammer should be mistaken for a saw. The two have different functions.

The function of science, as I see it, is to help us describe and understand the world intellectually. But there's clearly more to life than that. For example, if you had never tasted honey, I could spend all day telling you how bees make it, and what its chemical makeup is, but you wouldn't really know what it tastes like until you tried some.

Explanation can't replace experience. These are also two different things, and they only conflict if we think one can replace the other. William Blake didn't have geology in mind when he talked about seeing a world in a grain of sand. He was talking about experience, not explanation. Both are essential, and they can even compliment each other. They certainly do for me--my experience of nature gets more profound and moving as I learn more about how science can explain nature. I loved the experience of going to the beach before I learned anything about beach geology, and now I'll love it even more, because I understand it better. The two worlds enlarge each other. And a grain of sand can hold more worlds than one.

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