(geology) a geologically long period of time during which the magnetic field of the earth retains the same polarity. The magnetic field may reverse during such a period for a geologically short period of time (a magnetic event)
noun 1. . noun 1. an imaginary line on the earth’s surface, near the equator, at all points on which there is no magnetic dip Also called aclinic line magnetic equator A line connecting all points on the earth’s surface at which the magnetic field is parallel to the Earth’s surface. A balanced magnetic needle […]
noun 1. a region of space near a magnet, electric current, or moving charged particle in which a magnetic force acts on any other magnet, electric current, or moving charged particle. 2. . noun 1. a field of force surrounding a permanent magnet or a moving charged particle, in which another permanent magnet or moving […]
- Magnetic field of the earth
The magnetic field (see magnetism) that surrounds and permeates the Earth. It is the presence of this field that causes compass needles to line up in a north-south direction. The origin of the Earth’s magnetic field is poorly understood at the present time.
- Magnetic field reversals
Changes in direction or orientation of the magnetic field of the Earth that have occurred from time to time. (Several hundred are known in the geological record.) Sometimes the north magnetic pole is near the geographic North Pole and sometimes near the South Pole in Antarctica. Note: The causes of these reversals are not known […]