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What is Geologic Time?
This webpage of the National Park Service (NPS) and United States Geological Survey (USGS) discusses geologic time and what it represents. Beginning about 4.6 billion years ago and ending in the present day, this site exhibits (to scale) the various eras, periods, eons, and epochs of Earth's history with a downloadable geologic time scale available. Links provide maps of what the Earth looked like at various times in its history, as well as a description of how scientists developed the time scale and how they know the age of the Earth.
Intended for grade levels:
  • Middle (6-8)
  • High (9-12)
  • College (13-14)
Type of resource:
  • Text:
    • Ref. material
Subject:
  • Geological Sciences:
    • Geologic time
Technical requirements:
Selected resources require Adobe Acrobat reader.
Cost / Copyright:
No cost
Information presented on this web site is considered public information and may be distributed or copied. Use of appropriate byline/photo/image credit is requested.
DLESE Catalog ID: DLESE-000-000-002-326
Related resources:
This resource is referenced by 'Earth Science Sites of the Week Archive'
This resource is referenced by 'USGS Geology in the Parks'
Resource contact / Creator / Publisher:
Publisher: United States Geological Survey
http://wrgis.wr.usgs.gov

Publisher: National Park Service, Geolgical Resources Division