Lines of Earth's Magnetic Field
This figure indicates lines of magnetic force of a bar magnet which is located at the center of the earth with 11° inclined to the rotation axis. Geomagnetic field is produced through a dynamo process within the core, but is well approximated by this magnetic force of a bar magnet. N and S poles of the bar magnet come to the southern and northern hemispheres, respectively. Hence, the line of the geomagnetic field is directed upward in the southern hemisphere, downward in the northern hemisphere, and horizontal in the equatorial area. The reason for a compass needle moving horizontally is because the needle's center of gravity is adjusted according to the latitude of the area used for.
It was paleomagnetism that revealed the fact that the past geomagnetic field reversed many times. There are quite a few good textbooks which introduce paleomagnetism and rock magnetism and some of them are listed below. Hence, this homepage does not intend to present thorough introduction to the field, but rather to provide what is often missing in the standard text books such as easy and detailed derivation of formulas. Hence, description presented here might be too lengthy and redundant for talented people.
Textbooks on paleomagnetism and rock magnetism:
- Butler, R. F., Paleomagnetism, 319 pp., Blackwell Scientific Publications, Cambridge, USA, 1992.
- Dunlop, D. J., and O. Ozdemir, Rock Magnetism --- Fundamentals and frontiers ---, 573 pp., Cambridge University Press, Cambridge, 1997.
- McElhinny, M. W., and P. L. McFadden, Paleomagnetism --- Continents and Oceans ---, 386 pp., Academic Press, San Diego, 2000.
- Tarling, D. H., Palaeomagnetism --- Principles and Applications in Geology, Geophysics and Archeology, 379 pp., Chapman and Hall Ltd, London, 1983.
- Tauxe, L., Paleomagnetic Principles and Practice, 299 pp., Kluwer Academic Publishers, Dordrecht, 1998.