Archeomagnetic and paleomagnetic dating
Van der Voo, 1988, 1990; Torsvick et al., 2012 ), or to determine more or less local tectonic rotations (e.g.
in the Western Alps – Westphal, 1973; Henry, 1992; Thomas et al., 1999; Maffione et al., 2008 ).
Magnetic stripes are the result of reversals of the Earth's field and seafloor spreading.
New oceanic crust is magnetized as it forms and then it moves away from the ridge in both directions.
Among a total of 90 samples from hearths remains of six dwelling sites, the characteristic remanent magnetization components were isolated from 70 samples using the progressive alternating field demagnetizations and considered to record faithfully a thermoremanent magnetization at the timing of the last cooling of the hearths.
Two different approaches were made to determine the archeomagnetic ages: One is the conventional method using the relocated paleosecular variation (PSV) curve obtained from southwestern Japan.
As early as the 18th century, it was noticed that compass needles deviated near strongly magnetized outcrops.
Certain minerals in rocks 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.
In 1797, Von Humboldt attributed this magnetization to lightning strikes (and lightning strikes do often magnetize surface rocks).
In the 19th century studies of the direction of magnetization in rocks showed that some recent lavas were magnetized parallel to the Earth's magnetic field. Blackett provided a major impetus to paleomagnetism by inventing a sensitive astatic magnetometer in 1956.