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File:Geological time spiral.png

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Original file ‎(2,424 × 2,145 pixels, file size: 1.86 MB, MIME type: image/png)
Picture of the day This image was selected as picture of the day on Wikimedia Commons for . It was captioned as follows:
English: A diagram of the geological time scale

Summary[edit]

Description
English: A diagram of the geological time scale
Esperanto: Diagramo montranta la geologian temposkalon
Français : Diagramme montrant l'échelle des temps géologiques.
Date (Version 1.1)
Source Graham, Joseph, Newman, William, and Stacy, John, 2008, The geologic time spiral—A path to the past (ver. 1.1): U.S. Geological Survey General Information Product 58, poster, 1 sheet. Available online at http://pubs.usgs.gov/gip/2008/58/
Author United States Geological Survey
Other versions

This file was derived from  Geologica time USGS.png: Geologica time USGS.png
Derivative works of this file:

Caption[edit]

Original source: http://pubs.usgs.gov/gip/2008/58/geotimespiral_text.pdf

The Earth is very old—4.5 billion years or more according to scientific estimates. Most of the evidence for an ancient Earth is contained in the rocks that form the Earth's crust. The rock layers themselves—like pages in a long and complicated history—record the events of the past, and buried within them are the remains of life—the plants and animals that evolved from organic structures that existed 3 billion years ago.

Also contained in rocks once molten are radioactive elements whose isotopes provide Earth with an atomic clock. Within these rocks, "parent" isotopes decay at a predictable rate to form "daughter" isotopes. By determining the relative amounts of parent and daughter isotopes, the age of these rocks can be calculated. Thus, the scientific evidence from rock layers, from fossils, and from the ages of rocks as measured by atomic clocks attests to a very old Earth.

See USGS Fact Sheet 2007-3015 at http://pubs.usgs.gov/fs/2007/3015/ for ages of geologic time periods. Ages in the spiral have been rounded from the age estimates in the Fact Sheet. B.Y., billion years; M.Y., million years. For more information, see the booklet on Geologic Time at http://pubs.usgs.gov/gip/geotime/.

Licensing[edit]

Public domain This image is in the public domain in the United States because it only contains materials that originally came from the United States Geological Survey, an agency of the United States Department of the Interior. For more information, see the official USGS copyright policy.

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Date/TimeThumbnailDimensionsUserComment
current00:05, 6 July 2012Thumbnail for version as of 00:05, 6 July 20122,424 × 2,145 (1.86 MB)JohnnyMrNinjaSame image reduced from 6MB to 1.85MB. Removed unused transparency layer, indexed colors and increased compression, using en:GIMP.
22:04, 19 March 2009Thumbnail for version as of 22:04, 19 March 20092,424 × 2,145 (6.03 MB)NotyourbroomRecropped my own version to have borders similar to the original upload.
22:00, 19 March 2009Thumbnail for version as of 22:00, 19 March 20092,599 × 2,458 (6.06 MB)NotyourbroomMuch higher-res version (2599x2458@300DPI) cropped from the original PDF source.
22:51, 29 December 2008Thumbnail for version as of 22:51, 29 December 20081,617 × 1,454 (752 KB)Mwtoews{{Information |Description={{en|1=...}} |Source=USGS |Author=USGS |Date= |Permission= |other_versions= }} <!--{{ImageUpload|full}}-->

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