Description
Item Description:Title from title screen (viewed on Jan. 21, 2009).
Electronic resource.
Physical Description:v, 37 pages : digital, PDF file.
Format:Mode of access: Internet from the USGS web site. Address as of 1/21/09: http://pubs.usgs.gov/sir/2005/5023/pdf/SIR2005-5023.pdf ; current access available via PURL.
Bibliography:Includes bibliographical references (pages 19-20).