Consider, for example, the rock in the picture above. It doesn't look like much, does it? It sits in a parking lot at a trailhead near Boulder, Colorado, and people walk by every day without ever noticing it. But that rock has a story to tell.
It comes from a layer of rock in the canyons above Boulder known as the Coal Creek Formation. If you look at it closely, you see that it's made of smaller rocks--it's a type of rock called conglomerate. The constituent rocks are slightly rounded, like river rocks, because that's exactly what they once were. Long ago, they were part of a rocky riverbank a few miles from a mountain range. But no animals roamed that bank, and no trees shaded it. Animals and trees didn't exist yet, because that riverbank existed 1700 million years ago.
Even then, the pebbles inside that rock were ancient by our standards. They had eroded out of rocks formed millions of years before, when the ancient core of North America colliding with a line of volcanic islands, which slowly smashed together to create the first land that would become Colorado. Mountains rose in the collision, and then began to erode away, as mountains constantly do. The riverbank was eventually buried, and the pebbles and sand solidified into a layer of conglomerate. Then it was buried deeper and deeper, until eventually it was miles underground, where the heat and pressure fused the pebbles and sand together into a metamorphic rock called quartzite. The conglomerate had become a metaconglomerate. In some places where this rock appears today, you can see where the original river pebbles were warped and stretched in its journey through the depths.
A billion and a half years ago, then, our boulder was part of a layer of rock buried deep in the earth. And there it stayed, for hundreds of millions of years. Up above, single-celled life slowly evolved into complex organisms like early plants and animals. Some of the fish came onto the land and became amphibians, and some of the amphibians evolved into early reptiles. Finally, after 1400 million years, our rock began to rise again. Far-off tectonic forces were lifting a new mountain range, called the Ancestral Rocky Mountains. The Coal Creek formation rose to the surface, and was then hoisted into the air as a part of the mountains. Once again, erosion set in, and parts of the formation eroded into pebbles in mountain streams. Aprons of rocky debris spread out of the dwindling mountains onto the flatlands. One day, they would become the soaring red cliffs of Red Rocks Amphitheater and the Boulder Flatirons. Finally, the Ancestral Rockies crumbled into a sea of sand dunes (which would one day form the rocks at Garden of the Gods), which was in turn covered by an actual, shallow sea.
Elsewhere, dinosaurs evolved and grew into giants, who eventually migrated across the Jurassic coast of Colorado, leaving their huge footprints and bones in the sand. The seas rose again, and giant reptiles patrolled the waters, while pterosaurs soared above the waves like scaly pelicans. Then the sea retreated again around 67 million years ago, as a third set of mountains--called the Laramide Rockies--started to rise. Triceratops and T rex roamed the rainforests below, leaving more bones and footprints along the Front Range, before they were killed by an asteroid that firebombed North America. All the while, the Coal Creek formation kept rising with the mountains.
The Laramide Rockies began eroding as soon as they started to rise, and parts of the Coal Creek Formation again fell into mountain streams, creating a new generation of river rocks. Giant boulders southwest of Denver tell us that enormous floods once roared out of the mountains, powerful enough to carry refrigerator-sized rocks for nearly fifty miles. Eventually, all the erosion nearly buried the Laramide Rockies in their own debris. The high plains rose nearly to the tops of the mountains in a smooth incline, as they still do in southern Wyoming. The surface of the plain was high above the current sites of the cities along the Front Range. Our boulder was still part of a larger rock, which was (probably) buried once again.
Finally, around 5 million years ago, the land began to rise again (or perhaps the climate grew wetter) and rivers began carving up the landscape once again. The hard rock in the buried mountains resisted erosion, and the mountains began to emerge from their debris. These were the modern Rockies--the fourth mountain range our rock has seen. Earth entered one of its periodic ice ages, and glaciers began to descend from the mountains. They would stick around for 100,000 years or so, carving the high peaks into their current dramatic form, and then retreat for a few millennia during a brief, warm recess. Human civilization has arisen during the latest recess.
Down lower, when the ground around Boulder was still a few hundred feet higher than it is today, our rock finally eroded out a cliff and fell into Coal Creek. Its rounded shape tells us that floods knocked it against other rocks and ground away its edges, and its large size tells us these were powerful floods--only a flood can carry a rock that big. One of these floods finally carried it out of the mountains and deposited it on a flat plain. That plain was left standing by erosion around it, and now it's a mesa (technically a pediment) known as Rocky Flats. Rocky Flats is now notorious for being radioactive, due to careless handling of nuclear waste by some recently-evolved primates. At some point, those primates built a parking lot, and put our boulder there as a decoration. And there it sits. For now.
Will it still be sitting there when we are gone? It certainly could be--we are ephemeral things by its standards--but how long we last will depend on how wise and lucky we turn out to be. In any case, in the short time we've been here, we've discovered science. And science has allowed us to look at that nondescript rock in a parking lot and see beyond its initial appearance, to the amazing, eons-long story it can tell. The rock can't appreciate the grandeur of its own story, but we can. That's a major reason science is so important--it gives us the knowledge we need to appreciate the hidden beauty of nature.
Of course, some people don't see science this way. They think science kills the wonder of nature by reducing it to equations and theories; by "unweaving the rainbow" as Keats put it. And science can be dry and boring, when it isn't communicated well. But it doesn't have to be. When it is communicated well, science can show us the astounding majesty of nature. I think the physicist Walter Lewin put this best (in a lecture on the beauty of rainbows): "Knowledge always adds. Knowledge never subtracts. Knowledge is hidden beauty." That nondescript rock in a parking lot is full of hidden beauty, once you know how to see it.
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Geology Underfoot Along Colorado's Front Range / Lon Abbott and Terri Cook I learned about this rock, and the Coal Creek formation, from this excellent book. My copy is falling apart, because I've tromped all over the Front Range with it in my backpack.
The Hidden Beauty of Rainbows / Walter Lewin
