In the 1960s, scientists found evidence that new material is indeed erupting along mid-ocean ridges. The scientists dived to the ocean floor in Alvin, a small submarine built to withstand the crushing pressures four kilometers down in the ocean. In a ridge’s central valley, Alvin’s crew found strange rocks shaped like pillows or like toothpaste squeezed from a tube. Such rocks form only when molten material hardens quickly after erupting under water. These rocks showed that molten material has erupted again and again along the mid-ocean ridge.

When scientists studied patterns in the rocks of the ocean floor, they found more support for sea-floor spreading. You read earlier that Earth behaves like a giant magnet, with a north pole and a south pole. Surprisingly, Earth’s magnetic poles have reversed themselves many times during Earth’s history. The last reversal happened 780,000 years ago. If the magnetic poles suddenly reversed themselves today, you would find that your compass needle points south.

Explanation:

I found this somewhere.

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3 years ago

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20 POINTS describe the outer core layer of the earth please dont copy from somewhere else

Katen [24]

The outer core of the Earth is a liquid layer and it is mainly made up of the metals iron and nickel.

It's also made up of small amounts of other substances.

The outer core is responsible for Earth's magnetic field.

The outer core is the second layer of the Earth.

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