On Sunday 27 September 2009 00:37:27 Michael Payne wrote: > http://en.wikipedia.org/wiki/Wyoming_craton > > First time I've seen the use of SI prefixes for years. I think Ga means > Giga Annum.
I've seen both "a" and "y" for year. Both have problems: Gy is gray and Pa is pascal. I don't know of anyone who deals with petayears, though. Pierre
