Twin Sisters (WA)

Survey type M-Dz (magnetic; digitized from contour maps)
Flown by U.S. Geological Survey
Date flown 09/62-10/62
Line spacing 1.6 (km)
Altitude 2134 (m) by barometer measurement
Total distance 1,673 (km)
References
Counties Skagit - Whatcom
Overlapping surveys

Data: Magnetic (M-Dz)