Maps showing aeromagnetic survey and interpretation of the Virgin Mountains Instant Study Area Clark County, Nevada

Data for the aeromagnetic map (fig. 1) of the Virgin Mountains Instant Study Area wre collected in 1978 and compiled at a scale of 1:62,500. North-south traverses were spaced at 0.8-km intervals at an altitude of about 300m above the surface of the ground. The contour interval is 20 and 100 gammas, depending on the steepness of local magnetic gradients in the Earth's magnetic field. A regional field  (the International Geomagnetic Reference Field - 1975) of approximately 5-6 gammas/km was removed from the data before contouring by computer.