» Aquifer Basics    Offers a brief definition of an aquifer along with pictures and information on various aquifer types, including sandstone and volcanic aquifer rocks.    http://capp.water.usgs.gov/aquiferBasics/

» Aquifers    Provides colored pictures and information on why water is important and how it's frequently used. Features include answers to frequently asked questions and photo galleries.    http://ga.water.usgs.gov/edu/earthgwaquifer.html

» Edwards Aquifer    Provides information on one of the world's most well-known aquifers. Features graphs and charts, images, essays, and pictures that describe how the aquifer formed.    http://www.edwardsaquifer.net/

» Georgia's Ground Water Resources    Includes details on what groundwater is, along with information on the cycle it goes through and its movement.    http://www.engr.uga.edu/service/extension/publications/b1096-cd.html

» South Dakota Aquifers    Learn more about aquifers by looking at South Dakota's aquifers. Discover what an aquifer is, where they can be found, and its significance to humans in general.    http://www.northern.edu/natsource/EARTH/Aquife1.htm