U.S. Geological Survey heavy metals program progress report 1968 - Field studies

The Heavy Metals program of the U.S. Geological Survey and the U.S. Bureau of Mines began in mid-1966 and thus at the end of calendar year 1968 was halfway through its third year. This progress report summarizes field studies carried out under the Geological Survey's part of the program during 1968. Topical studies for 1968 are summarized in U.S. Geological Survey Circular 622. Background of the program and results during 1966 and 1967 were reported in U.S. Geological Survey Circular 560 and will not be further discussed herein.