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16 Αυγ 2018 · Students will analyze a magnetic polarity map, calculate seafloor spreading rates, and present their findings. They will learn that magnetic reversals are caused by changes in Earth's core and prove seafloor spreading by magnetic patterns in ocean floor rocks.
The key was to marry two seemingly unrelated lines of research: the magnetic reversal timescale as determined from rocks of the continents and the magnetism of rocks from the bottom of the sea.
Spreading Rate from Magnetic Anomalies. Determining the spreading rate (rate of crust accreted to the plate) from the magnetic anomalies is done in several steps.
15 Φεβ 2021 · Mapping of the seafloor with magnetometers revealed lines of magnetic reversals on opposite sides of mid-ocean ridges. (USGS) Paleomagnetism is the study of the fixed orientation of a rock's magnetic minerals as originally aligned at the time of the rock's formation (simply, old magnetism).
11 Ιαν 2021 · Data from magnetometers dragged behind ships looking for enemy submarines in WWII discovered amazing magnetic patterns on the seafloor. The magnetic pole reverses from time to time. The north pole becomes the south pole, and the south pole becomes the north pole.
17 Σεπ 2020 · We present an updated oceanic crustal age grid and a set of complementary grids including spreading rate, asymmetry, direction, and obliquity. Our data set is based on a selected set of magnetic anomaly identifications and the plate tectonic model of Müller et al. (2019, 10.1029/2018TC005462).
Through analysis of seafloor magnetic anomalies and dating of reversal sequences on land, paleomagnetists have been developing a Geomagnetic Polarity Time Scale. The current time scale contains 184 polarity intervals in the last 83 million years (and therefore 183 reversals).
