Geology Labs On-Line, a fabulous site containing virtual labs, including Virtual Earthquake. The section called "Virtual Dating" is about determining the age of rocks and stuff.
THE ELECTRONIC VOLCANO Dartmouth U.
National Earthquake Information Center US Geological Survey
University of California Museum of Paleontology’s Plate Tectonics site, with animations of continental drift.
Introduction to Geologic Principles U. California Santa Cruz
Physical Geology Online Version - University of Houston
Yellowstone Net Geyser Information. This site will make you want to see it for yourself.
Glacier, a site about Antarctica, where you can learn about ice, oceans and meteorology.
Introduction to Geology Georgia Perimeter College, Dr. Pamela Gore (great notes)
The National Oceanic & Atmospheric Administration’s Websites. Be sure to click on the National Hurricane Center, Today’s Weather, Satellite Imagery and Atmospheric and Space Sciences.