Thorman, C.H., 1994, Introduction to field trip guidebook, in Thorman, C.H., and Lane, D.E., eds., USGS Research on Mineral Resources - 1994, Part B - Guidebook for Field Trips, Ninth V.E. McKelvey Forum on Mineral and Energy Resources: U.S. Geological Survey Circular 1103-B, p. 1-2.