How old is the Earth?

Here is a link to a USGS webpage about scientists using  fossils and rocks to  understand the age of the planet:
http://pubs.usgs.gov/gip/fossils/contents.htmlweeblylink_new_window



The lower box represents layers of the earth labeled with events occurring at the time the layer of earth was deposited.  The upper box is the same layers after they are uplifted or shifted due to geologic forces such as earthquakes.

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