Original Geologic Time Machine conceived and created by Allen Collins -- 11/26/94.

Revised format and concept by Robert Guralnick and Brian R. Speer -- 9/15/95.

Current format and concept by Brian R. Speer -- 6/4/98.

Reordered with younger times above older times, as usually seen in the rocks themselves, by AGC -- 12/14/98.

Geologic Time pages updated to reflect Geological Society of America (GSA) 1999 Geologic Timescale, compiled by A.R. Palmer and J. Geissman -- S. Rieboldt, Nov. 2002