Discovery Gallery

The Evolving Earth

Geographic features seemingly so permanent as mountains change constantly. Continents--features riding atop the giant plates forming the earth's crust--have shifted dramatically over time. For example, during the average person's sixty-year life span, North America and Africa move further apart by about six feet. Minerals and rocks record the long-term dynamics of the earth. They are the signs geologists decipher in order to read our planet's history. Some also preserve traces of short-term events, like volcanic activity, that formed them ages ago. Our planet has also been bombarded by meteorites since it formed about 4.5 billion years ago. Meteorites provide us with information about the formation of the Solar System and the composition of other planets.

• Minerals, Crystals, and Gems: Revealing Earth's History
• Smithsonite
• Fluorescents: Minerals that Glow in the Dark
• From Crystal to Gem
• Meteorites

For more information on minerals, gems, and meteorites, see Earth Sciences at the National Science Foundation.

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