Map showing aeromagnetic interpretation of the Baker-Cypress BLM Instant Study Area and Timbered Crater Forest Service Further Planning Areas, Modoc, Shasta, and Siskiyou counties, California

The data for the aeromagnetic map of the Baker-Cypress and Timbered crater areas were collected in 1978 and compiled at a scale of 1 :62,500 (U,S, Geological Survey, 1979). East-west traverses were spaced at 0.8-km intervals at a constant altitude of 1370 m (4500 ft) above sea level, Contour interval is 20 and 100 gammas, depending upon the steepness of local gradients in the Earth's magnetic field. A regional magnetic field (the International Geomagnetic Reference Field - 1975, updated to the month flown) of approximately 5-6 gammas/km was removed from the data be fore con touring.