1. n. [Geophysics]

The study of the Earth's magnetic field, a branch of geophysics that began with the observation by British scientist William Gilbert (1544 to 1603) that the Earth is a magnet. Variations in the magnetic field can be used to determine the extent of sedimentary basins and the depth to basement rocks, as well as to differentiate between igneous rocks and certain sedimentary rocks such as salt. High-resolution magnetic surveys can also be used to determine the locations of oil pipelines and production equipment.

See: deep tow,  downward continuation,  electromagnetic method,  geophysics,  inclinometer,  permeability,  potential field,  remote sensing,  spherical divergence,  survey,  upward continuation