This is the time scale for the North America Tapestry of Time and Terrain map.
Home: http://pubs.usgs.gov/imap/i2781/
Image: http://pubs.usgs.gov/imap/i2781/i2781_c_low.pdf 144 dpi, encoded to 72 dpi JPEG, compressed slightly to fit within Wikipedia 2MB limit.
English Wikipedia, original upload 15 April 2005 by SEWilco