Description
Physical Description:v, 24 pages : illustrations (some color) ; 28 cm.
Also available via Internet from USGS web site. Address as of 11/8/06: http://pubs.er.usgs.gov/usgspubs/b/b1742B; current access available via PURL.
Bibliography:Includes bibliographical references (pages 19-20)
Additional Physical Form available Note:Also available via Internet from USGS web site. Address as of 11/8/06: http://pubs.er.usgs.gov/usgspubs/b/b1742B; current access available via PURL.