01195cam a22002771 4500 gs 59000160 DLC 20260227111408.0 780715s1959 dcuabd b f000 0 eng gs 59000160 (OCoLC)4055613 DLC OClU ISS OCoLC DLC premarc QE75 .P9 no. 309 557.7 I 19.16:309/ Heyl, Allen Van, 1918- The geology of the upper Mississippi Valley zinc-lead distict, by Allen V. Heyl, Jr. [and others] With special sections by Arthur E. Flint. Prepared in cooperation with the Wisconsin Geological and Natural History Survey, the Iowa Geological Survey, and the Illinois State Geological Survey. Washington, U.S. Govt. Print. Off., 1959. x, 310 p. illus., maps (24 fold. 22 col., in portfolio) diagrs., profiles, tables. 29 cm. Geological Survey (U.S.). Professional paper, 309 Bibliography: p. 296-303. Geology Mississippi River Valley. Zinc mines and mining Mississippi River Valley. Upper Mississippi Valley zinc-lead district. 29344 29344