Is there a color standard for indicating geological epochs?

[Callery, Bernadette]

I'm about to begin looking for a color standard for indicating geological
epochs - particularly for the US - with the assumption that there IS such a
standard - and will begin looking in USGS publications.  What I'm looking
for - on behalf of our Exhibits Dept. - are the specific Pantone, etc.
colors.  

If anyone can point me in the right direction, I'd be grateful.
	Many thanks, Bernadette

Bernadette G. Callery, Museum Librarian
Carnegie Museum of Natural History
4400 Forbes Ave.
Pittsburgh, PA  15213-4080
Phone: 412-622-8870; FAX: 412-622-8837
Email: calleryb at carnegiemuseums.org