USGS Geologic Names Lexicon http://ngmdb.usgs.gov/Geolex/geolex_home.html
The British Geological Survey Lexicon of Named Rock Units http://www.bgs.ac.uk/lexicon/lexicon_intro.html
Lexicon of Canadian Geological Names http://cgkn1.cgkn.net/weblex/weblex_e.pl
These links to web pages are provided for your benefit. It does not constitute an endorsement from the AAPG or the AAPG Foundation Library.