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Also, when magnetized minerals become disaggregated from their parent rocks by erosion and are carried into a basin, they will tend to align themselves parallel to the earth's magnetic field as they settle in still water.
When the deposit into which they settle hardens into rock, the magnetization will be fixed.
Paleomagnetic studies of the ocean floor have been of decisive importance in establishing the modern theories of continental drift and seafloor spreadingseafloor spreading,theory of lithospheric evolution that holds that the ocean floors are spreading outward from vast underwater ridges.
First proposed in the early 1960s by the American geologist Harry H......
Though first proposed by American geologist Frank Bursley Taylor in a lecture in 1908, the first detailed theory of.....
could be tested by ascertaining the magnetic characteristics of ancient rocks; however, it was not until after World War II that rock paleomagnetism data was gathered.
The first step in paleomagnetic investigations is to determine what types of magnetization a given rock has.Another type of stable remanent magnetization is chemical remanent magnetization (CRM), which arises during the growth of ferromagnetic grains in a magnetic field.Viscous remanent magnetization (VRM) arises during the prolonged action of a magnetic field on a rock and is a result of thermal activation and diffusion processes.The cause of these magnetic "flip-flops" is not clearly understood.Ideas of paleomagnetism began in the late 1920s, when French physicist Mercanton, suggested that because today's magnetic field is close to the earth's rotational axis, continental driftcontinental drift,geological theory that the relative positions of the continents on the earth's surface have changed considerably through geologic time.