1. 46. Total Intensity aeromagnetic map [and accompanying aeromngnetic profiles] of parts of Clearwater. Polk, and Red Lake Counties, Minn., aeromagnetic survey 1947 by J. R. Balsey and M. E. Hill. Scale 1 m. = 1 in. for map and 1 m. = 0.5 in. for profiles, contour interval 50 and 250 gammas, n. p. Bookmark Corporate/Agency Authors: Geophysical investigations map GP (series). Publisher: Geophysical investigations map GP (series). Date: 1951 SuDoc number: I 19.25/2:46/sh.1-2