EarthRef.org Digital Archive (ERDA) -- Cross-Section Formation of Magnetic Anomalies with Geologic Timescale

Description
This block diagram illustrates the formation of magnetic anomalies for the last four epochs in the earth's magnetic reversal history. The first block diagram shows how mantle upwelling in response to ocean floor spreading produces magmas that form the oceanic crust during the reversed Gilbert epoch. At 3.3 Ma the magnetic field of the earth changed from reversed to normal, and newly emplaced oceanic crust started to be normally magnetized, until the magnetic field reversed again at the beginning of the Matuyama reversed epoch. Note that this image is highly simplified and that the magnetic stripes on real ocean floor are much more irregular. Amongst the many causes that might be responsible for this, it is probably the irregular shape of individual volcanoes making up the new oceanic crust.

Keywords
ERESE, geologic time scale, geomagnetic timescale, magnetic anomalies, magnetic anomaly, magnetic reversals, magnetic stripes, mid-ocean ridge, seafloor spreading, spreading center

Copyright Owner
Enduring Resources for Earth Science Education (ERESE)

Copyright Description
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