IT’S SO BORING, the usual human’s-eye view. Seasons come and go, but terra firma itself never varies. Even an earthquake or a mudslide seems like a random incident unconnected to any larger or more complex patterns.
But put on the lenses of a geologist and take another look. Reading the stories imprinted on the rocks and crystals gives scientists the ability to examine our world as it has evolved over millions, even billions, of years. From this vantage point, it is easy to see that Earth has been—and continues to be—a lively cauldron of change. Just as stop-action photography shows how buds burst into flower, geology gives us a picture of a living, changing planet. It even has a heartbeat of sorts, in pulsed releases of vast amounts of inner heat. The most recent occurred when dinosaurs still roamed, as Roger L. Larson discusses in “The Mid-Cretaceous Superplume Episode,” on page 22.
As scientists draw on records of past tremors, it becomes clear that earthquakes, which seemed to be isolated, can interact with one another. In “Earthquake Conversations,” on page 82, Ross S. Stein explains how these surprising interconnected effects could give nations, cities and individuals new power to evaluate local vulnerability to temblors.
In another place where taking the long view alters our everyday notions, we learn that erosion—long familiar as the great leveler—has also had a hand in shaping the tallest peaks, the Himalayas. Eroding land, by reducing weight, accelerates tectonic processes, creating an uplift. Turn to page 74 for “How Erosion Builds Mountains,” by Nicholas Pinter and Mark T. Brandon.
Deep under the morphing surface, the interior simmers. The churning mantle creates and powers the primary magnetic field that surrounds the sphere. The polarity of this field reverses every so often, which has long puzzled researchers. “Probing the Geodynamo,” by Gary A. Glatzmaier and Peter Olson, on page 28, tells of new, intriguing clues about how the next reversal may begin.
So join us for a jaunt in geology’s rock-encrusted time machine. The articles in this special edition promise a rare look inside the mysterious and little-appreciated underfoot activities of the world we all call home.