This is a cover page. To go to the actual document, click on the title.
The document is in PDF format (0.5MB) and requires Adobe Acrobat ReaderTM v. 3.0 or later. Therefore, you will need Acrobat Reader 3.0 to view and print. If you do not have Acrobat Reader 3.0, you will need to download the program.
Click here to Download Adobe Acrobat 3.0 and follow the download and installation instructions provided. After downloading Acrobat, configure your WWW Browser to use Acrobat as a helper application.

U.S. Geological Survey


Comments and feedback: gellis@
Last modified: 2/20/98 (JGN)