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The Earth's magnetic field has alternated between periods of normal polarity, in which the predominant direction of the field was the same as the present direction, and reverse polarity, in which it was the opposite. These periods are called chrons. Reversal occurrences are statistically random.
The following is a list of geomagnetic reversals, showing the ages of the beginning and end of each period of normal polarity (where the polarity matches the current direction). Source for the last 83 million years: Cande and Kent, 1995. [1] Ages are in million years before present (mya).
The Gauss–Matuyama Reversal was a geologic event approximately 2.58 Ma when the Earth's magnetic field underwent a geomagnetic reversal from normal polarity (Gauss Chron) to reverse polarity (Matuyama Chron). The reversal is named after German physicist Johann Carl Friedrich Gauss and Japanese geophysicist Motonori Matuyama. The Gauss ...
While life on Earth has weathered multiple magnetic reversals over more than 100 million years, “we’ve never experienced a reversal when modern technology was present,” Brown said.
The polarity of the Earth's magnetic field is recorded in igneous rocks, and reversals of the field are thus detectable as "stripes" centered on mid-ocean ridges where the sea floor is spreading, while the stability of the geomagnetic poles between reversals has allowed paleomagnetism to track the past motion of continents.
A polarity chron, or in context chron, [4] is the time interval between polarity reversals of Earth's magnetic field. [5] It is the time interval represented by a magnetostratigraphic polarity unit. It represents a certain time period in geologic history where the Earth's magnetic field was in predominantly a "normal" or "reversed" position ...
Earth's magnetic polarity reversals in last 5 million years. Dark regions represent normal polarity (same as present field); light regions represent reversed polarity. Magnetostratigraphy uses the polarity reversal history of Earth's magnetic field recorded in rocks to determine the age of those rocks.
Earth’s inner core, a red-hot ball of iron 1,800 miles below our feet, stopped spinning recently, and it may now be reversing directions, according to an analysis of seismic activity.