SA Special Editions

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

The North American continent may be more nomadic than most of its inhabitants

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

Scientists have wondered why the polarity of Earth's magnetic field occasionally reverses. Recent studies of fer intriguing clues about how the next reversal may begin

This interactive zone may be the most dynamic part of the planet, directly affecting Earth's rotation and magnetic field

The high-standing continents owe their existence to Earth's long history of plate-tectonic activity

Modern sonar techniques map the continental margins of the U.S. and reveal the richly varied scenery usually hidden underwater.

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

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

An understanding of how tectonic, erosional and climatic forces interact to shape mountains permits clearer insights into Earth's history

Contrary to prevailing wisdom, large earthquakes can trigger or inhibit one another in unexpected ways. This exciting discovery could dramatically improve scientists' ability to pinpoint future shocks

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