Southwest Illinois (IL)

Survey type M-Dz (magnetic; digitized from contour maps)
Flown by Michigan State University
Date flown ?/71
Line spacing 1.6 (km)
Altitude 914.4 (m) by barometer measurement
Total distance 11,104 (km)
References
Counties Alexander - Franklin - Jackson - Johnson - Perry - Pulaski - Randolph - Union - Williamson - Ballard - Cape Girardeau - Mississippi - Perry - Sainte Genevieve - Scott
Overlapping surveys

Data: Magnetic (M-Dz)