Original page content written and completed by:
pdp -- 4/30/94
brs 10/4/95 -- updated format and added plant search.
Tectonics and Paleoclimate material added 1 May 2000 by:
Pliocene pages updated to reflect Geological Society of America (GSA) 1999 Geologic Timescale, compiled by A.R. Palmer and J. Geissman
-- S. Rieboldt, Nov. 2002