Key Earth Science Links
Geologic Time Scales
Web Geological Time Machine, University of California , Berkeley . Excellent site for gathering information about geologic time quickly. Click on a period from the time scale to get a general summary of that time. From the summary you can navigate to information concerning the stratigraphy (rock layering and famous rock deposits), ancient life (fossils), localities (famous deposits), and tectonics (what the earth's surface was like) of the time. If you are interested in subdivision of periods into systems and stages, scroll down the summary page after the buttons for ancient life through tectonics. A brief history of the time scale can be found at Historical Perspective part of the website.
Geologic Time Scale , Enchanted Learning. Provides a fun time scale for elementary and middle school children. The time scale is divided into periods (and epoch for the Quaternary), with a column for pivotal events that links to illustrations of creatures from that time at other parts of their website.
Geologic Time, Palaeos. Excellent site for a wide array of information concerning earth history. Scroll down to get to the time scale, which is subdivided to age (stage). Click on a time to get the general history, plate tectonics, paleogeography, climate, life, mass extinctions, and more links for that time period. Thousands of images. Some technical information.
Geologic Time for background information on how geologists divide geologic time, relative time scales, radiometric time scales, index fossils, and the age of the earth.
Time Scale Charts , International Commission on Stratigraphy. This research group of scientific organizations publishes a geologic time chart, which is periodically updated with new scientific findings and used by geologists and paleontologists. Choose from several versions of time charts in page size pdf formats. Useful as a reference for the absolute boundaries of the time divisions, rather than information concerning specific time periods. Also, provides free downloadable software to make your own time charts.
Geo-When Database, Purdue University. This website is useful for determining ages and correlations of geologic stage names from around the world. Based on data from the Gradstein and others, 2004, international geologic time scale.