The Earth acts like a large spherical magnet: it is surrounded by a magnetic field that changes with time and location. The field is generated by a dipole magnet i. The axis of the dipole is offset from the axis of the Earth's rotation by approximately 11 degrees. This means that the north and south geographic poles and the north and south magnetic poles are not located in the same place. At any point and time, the Earth's magnetic field is characterized by a direction and intensity which can be measured. Often the parameters measured are the magnetic declination , D, the horizontal intensity, H, and the vertical intensity, Z.
What are the Earth's layers?
Geomagnetism Frequently Asked Questions
Paleomagnetism , or palaeomagnetism , is the study of the record of the Earth's magnetic field in rocks, sediment, or archeological materials. Magnetic minerals in rocks can lock-in a record of the direction and intensity of the magnetic field when they form. This record provides information on the past behavior of Earth's magnetic field and the past location of tectonic plates. The record of geomagnetic reversals preserved in volcanic and sedimentary rock sequences magnetostratigraphy provides a time-scale that is used as a geochronologic tool.
The Age of the Ocean Floor
Oceanic crust is about 6 km 4 miles thick. It is composed of several layers, not including the overlying sediment. The topmost layer, about metres 1, feet thick, includes lavas made of basalt that is, rock material consisting largely of plagioclase [ feldspar ] and pyroxene.
Physical Geology Tulane University Prof. Stephen A. Tectonic theories attempt to explain why mountains, earthquakes, and volcanoes occur where they do, the ages of deformational events, and the ages and shapes of continents and ocean basins. Alfred Wegner was a German Meteorologist in the early s who studied ancient climates.