Description
Item Description:Title from .DJVU title screen (viewed on Dec. 24, 2008).
Electronic resource.
Physical Description:65 pages : illustrations, maps ; 26 cm.
Format:Mode of access: Internet from the USGS web site (.DJVU file). Address as of 12/24/08: http://pubs.er.usgs.gov/usgspubs/cir/cir918 ; current access available via PURL.
Bibliography:Includes bibliographical references (pages 35-37).