Wis.-Ill. Lead-Zinc '48 (WI)

Survey type M-Dz (magnetic; digitized from contour maps)
Flown by U.S. Geological Survey
Date flown 08/48
Line spacing 0.4 (km)
Altitude 548.6 (m) by barometer measurement
Total distance 4,441 (km)
References
Counties Jo Daviess - Jackson - Grant - Iowa - Lafayette
Overlapping surveys

Data: Magnetic (M-Dz)