USGS-The Learning Web - Learn how Biology, Geology, Hydrology, and Geography can help us understand our changing world. - http://education.usgs.gov/
Volcano - K-12 exercises about volcanoes around the world. - http://www.k12.hi.us/~kapunaha/student_projects/volc_blowout/volcano_main.htm
Earth Science Week - Earth science education event in October of each year. Web site features educational activities, geology questions and answers, and links to other geologic education resources. - http://www.earthsciweek.org/
Sands of the World - An interactive unit on the generation of sand geared toward grades 3-12. - http://www.chariho.k12.ri.us/curriculum/MISmart/ocean/sands.htm
Become a Rock Detective - A program based on classroom-tested earth science mysteries; large kit of rocks, fossils and minerals; step-by-step instructions; for science- or non-science oriented K-12 teachers. - http://www.rockdetective.org/
Earth Science Educational Standards - Summary of National Academy of Sciences pre-college (K-12) science education standards related to earth sciences, with links to useful web sites related to each topic. Site maintained by Kentucky Geological Survey. - http://www.uky.edu/KGS/education/edustand.html
Virginia Earth Science Resource Page - Sponsored by the VA Dept. of Education. Teacher resources that support teaching earth science (mainly geology), particularly related to Virginia's Standards of Learning. - http://vtso.geol.vt.edu/vesr/
Volcano World - Great source of volcano information on the Web - http://volcano.und.nodak.edu/
Web Geological Time Machine - a great, sprawling geological and paleontological journey from the birth of the planet to today. - http://www.ucmp.berkeley.edu/help/timeform.html
This Dynamic Earth - Online version of a U.S. Geological Survey brochure on the topic of plate tectonics. The site seems appropriate for high-schoolers and above (and advanced middle schoolers). Covers the historical development of plate tectonics as a theory, how we see it i - http://pubs.usgs.gov/publications/text/dynamic.html