The presence of magnetic domains of alternating orientation parallel to the plate boundaries.
Evidence for Seafloor Spreading: Magnetic Reversals
Some of the most important evidence of seafloor spreading comes from magnetic reversals recorded in the ocean floor. Throughout Earth's history, the north and south magnetic poles have changed places many times. When the poles change places, the polarity of Earth's magnetic poles changes, as shown in Figure 4. When Earth's magnetic poles change places, this change is called a magnetic reversal.
Figure 4 The polarity of Earth's magnetic field changes over time.
Magnetic Reversals and Seafloor Spreading
The molten rock at the mid ocean ridges contains tiny grains of magnetic minerals. These mineral grains contain iron and are like compasses. They align with the magnetic field of the Earth. When the molten rock cools, the record of these tiny compasses remains in the rock. This record is then carried slowly away from the spreading center of the ridge as seafloor spreading occurs.
The Earth's crust is broken into many slowly moving plates. Sea floor spreading occurs at the mid ocean ridge where two plates are moving away from each other. Magma rises up from below and cools to form new seafloor rock
Because magnetic indicators in the rock point to either the north or south pole in parallel stripes adjacent to each other on either side of the mid Atlantic ridge. As the magma cools from seafloor spreading the magnetic direction is frozen into the rock creating the aforementioned stripes.
Evidence of magnetic reversal events in the basaltic rock on either side of the oceanic ridge mirrors the other side, providing proof that the crust is being created in both directions from the ridge.
Iron minerals help the seafloor spread by supporting the earth's magnetic pull.
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Lawrence W. Morley, Frederick John Vine, and Drummond Hoyle Matthews were the first to tie magnetic stripe anomalies to seafloor spreading. The magnetic anomalies was the first evidence that supported the theory of seafloor spreading.
Magnetic stripes and absolute ages of seafloor basalt.
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As mid ocean ridges create new seafloor over extended periods of time, the magnetic poles of the Earth reverse back and forth. The rocks on either side of a mid ocean ridge show the opposite magnetisms and appear striped. From knowing the approximate ages of these magnetic reversals, one can estimate the approximate age of each stripe.
The magnetic properties of rocks along the mid-oceanic ridges change alignment in a symmetrical manner.
pole reversals seafloor spreading
Because of the stripes at the sea floor which are magnetic minerals
Magnetic alignment of rocks, in alternating strips that run parallel to ridges, indicates reversals in Earth's magnetic field and provides further evidence of seafloor spreading.
Not really but sea floor sediments thickness increase with increased distance from spreading centers which is good evidence. Other evidence such as magnetic reversals, temperature, dating methods provide the best evidence of seafloor spreading
seafloor spreading
Magnetic Reversal
evidence from molten material evidence from magnetic stripes evidence from drilling samples
Lawrence W. Morley, Frederick John Vine, and Drummond Hoyle Matthews were the first to tie magnetic stripe anomalies to seafloor spreading. The magnetic anomalies was the first evidence that supported the theory of seafloor spreading.
They proved that the seafloor was spreading.
Magnetic stripes and absolute ages of seafloor basalt.
Earth got its north and south Pole's have geographic and magnetic north and south poles which makes an angle of nearly 5.6degree. magnetic field created due to core of earth is reversed during each 100 million year period. ie.magnetic north becomes south and vice's. seafloor spreading is a continuous event so for each 100my spread seafloor we get opposite polarised magnetic substances. That is called magnetic reversal
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