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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.

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. --The Editors

In the Beginning

The Evolution of Earth by Claude J. Allègre and Stephen H. Schneider
The evolution of this planet and its atmosphere gave rise to life, which shaped Earth's subsequent development. Our future lies in interpreting this geologic past and considering what changes--good and bad--may lie ahead.

Earth before Pangaea by Ian W. D. Dalziel
The North American continent may be more nomadic than most of its inhabitants.

The Mid-Cretaceous Superplume Episode by Roger L. Larson
Earth has an erratic "heartbeat" that can release vast amounts of heat from deep within the planet. The latest "pulse" occurred 120 million years ago.

Searching below the Surface

Probing the Geodynamo by Gary A. Glatzmaier and Peter Olson
Scientists have wondered why the polarity of Earth's magnetic field occasionally reverses. Recent studies offer intriguing clues about how the next reversal may begin.

The Core-Mantle Boundary by Raymond Jeanloz and Thorne Lay
This interactive zone may be the most dynamic part of the planet, directly affecting Earth's rotation and magnetic field.

The Evolution of Continental Crust by S. Ross Taylor and Scott M. McLennan
The high-standing continents owe their existence to Earth's long history of plate-tectonic activity.

Panoramas of the Seafloor by Lincoln F. Pratson and William F. Haxby
Modern sonar techniques map the continental margins of the U.S. and reveal the richly varied scenery usually hidden underwater.

Forces That Shape and Shake Earth

Sculpting Earth from Inside Out by Michael Gurnis
Powerful motions deep inside the planet do not merely shove fragments of the rocky shell horizontally around the globe--they also lift and lower entire continents.

Earth's Mantle below the Oceans by Enrico Bonatti
Samples collected from the ocean floor reveal how the mantle's convective forces shape Earth's surface, create its crust and perhaps even affect its rotation.

How Erosion Builds Mountains by Nicholas Pinter and Mark T. Brandon
An understanding of how tectonic, erosional and climatic forces interact to shape mountains permits clearer insights into Earth's history.

Earthquake Conversations by Ross S. Stein
Contrary to prevailing wisdom, large earthquakes can interact in unexpected ways. This exciting discovery could dramatically improve scientists' ability to pinpoint future shocks.

The Threat of Silent Earthquakes by Peter Cervelli
A lack of rumbling does not necessarily make an earthquake harmless. Some of the quiet types could presage devastating tsunamis or larger, ground-shaking shocks.

Web-only bonus article: New Light on Deep Earthquakes by Harry W. Green II
Until about 15 years ago, it was a mystery how deep earthquakes could occur. Recent results have now demonstrated mechanisms for such rock failures at great depths.