U.S. DEPARTMENT OF THE INTERIOR, Gale A. Norton, Secretary
U.S. GEOLOGICAL SURVEY, Charles G. Groat, Director
Reston, Virginia 2001
Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Free on application to the
U.S. Geological Survey
Branch of Information Services
Box 25286
Denver, CO 80225-0286