Seafloor Spreading and Oceanic Crust Review

Why does the ocean floor form symmetrical magnetic patterns on both sides of a mid-ocean ridge?

• The magnetic poles reverse and cause melting of seafloor rocks.

• Each eruption at the ridge records the current magnetic orientation as lava cools.

• The Earth's magnetic field pushes minerals equally on both sides of the ridge.

• Older crust realigns itself with younger crust to maintain symmetry.

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NGSS.HS-ESS1-5

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15. Multiple Choice: __________ occur when the orientation of Earth's magnetic field changes.

• Magnetic reversals

• Solar flares

• Earthquakes

• Volcanic eruptions

Seafloor spreading takes place along a mid-ocean ridge.

• True

• False

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NGSS.MS-ESS2-3

Oceanic crust is older when it is closer to a mid-ocean ridge than it is when it is farther away.

• True

• False

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NGSS.MS-ESS2-3

NGSS.MS-ESS2-2

High amounts of thermal energy is released from abyssal plains.

• True

• False

Magnetic bands on the ocean floor are evidence that Earth's magnetic field changes.

• True

• False

Seafloor spreading helped to support Alfred Wegener's hypothesis of continental drift.

• True

• False

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NGSS.MS-ESS2-3

The abyssal plain is flat due to an accumulation of __________ far from the ridge.

• sediment

• lava

• salt

• coral

Which statement best describes how new oceanic crust forms and moves across the ocean floor?

• Oceanic crust forms at deep-ocean trenches, moves toward the ridge, and thickens with sediment as it rises.

• Oceanic crust forms at mid-ocean ridges, moves outward across the abyssal plain as sediments build up, and eventually sinks into the mantle at a trench.

• Oceanic crust forms near continents, slowly drifts toward ridges, and melts beneath the abyssal plain.

• Oceanic crust forms under the abyssal plain and stays in place as sediments pile on top of it.

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NGSS.MS-ESS2-1

Which sequence best represents what happens as oceanic crust forms and moves across the ocean floor?

• Crust forms at C, thickens with sediment at B, and melts at A

• Crust forms at A, moves outward through B as sediments build up, and sinks into the mantle at C

• Crust forms evenly across B and remains in place under the sediment

• Crust forms at B, slides under the ridge at A, and later rises again at C

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NGSS.MS-ESS2-2

NGSS.MS-ESS2-1