Magnetic Reversal

Which evidence causes most scientists to believe that seafloor spreading occurs at the mid-Atlantic Ridge?

• Oceanic crust is oldest at the ridge.

• Large sedimentary folds exist in the mantle near the ridge.

• Oceanic crust on both sides of the ridge is less dense than continental crust.

• Oceanic crust on both sides of the ridge shows matching patterns of reversed and normal magnetic polarity.

Tags

NGSS.HS-ESS1-5

Base your answer to the following question on the information and diagram below. At intervals in the past, the Earth's magnetic field has reversed. The present North magnetic pole was once the South magnetic pole, and the present South magnetic pole was once the North magnetic pole. A record of these changes is preserved in the igneous rocks that formed at mid-ocean ridges and moved away from the ridges. The diagram below represents the pattern of normal and reversed magnetic polarity in the igneous rocks composing the ocean crust on the east side of a mid-ocean ridge. The igneous material along this mid-ocean ridge was found to be younger than the igneous material farther from the ridge. This fact supports the theory of

• crustal subsidence

• seafloor spreading

• superposition

• dynamic equilibrium

Tags

NGSS.HS-ESS1-5

The diagram below shows the magnetic polarity preserved by minerals within the bedrock of the oceanic crust near the Mid-Atlantic Ridge. Letters A, B, C, and D represent locations in the ocean-floor bedrock. The most recently formed bedrock is found at location.

• A

• B

• C

• D

Tags

NGSS.HS-ESS1-5

NGSS.HS-ESS2-1

A change of Earth's magnetic poles.

• Magnetic Reversal

• Subduction

• Sea-Floor Spreading

• Convection Current

event in which magnetic field reverses direction

• magnetic reversal

• magnetism

• normal polarity

• reversed polarity

magnetic field in which magnets orient themselves to point south

• reversed polarity

• magnetism

• normal polarity

• magnetic reversal

Which geological feature provides evidence for magnetic reversal?

• Volcanic islands

• Mid-ocean ridges

• Continental shelves

• Deep-sea trenches

What is the primary cause of magnetic reversal on Earth?

• Changes in Earth's orbit

• Shifts in tectonic plates

• Fluctuations in Earth's core dynamics

• Variations in solar radiation

How do scientists determine the age of oceanic crust using magnetic reversal?

• By measuring the thickness of sediment layers

• By analyzing the chemical composition of rocks

• By examining the pattern of magnetic stripes

• By observing the color of the ocean floor

Tags

NGSS.HS-ESS1-5

Which of the following best describes a magnetic reversal?

• A temporary weakening of Earth's magnetic field

• A complete flip in the direction of Earth's magnetic field

• A gradual shift in the position of the magnetic poles

• An increase in the strength of Earth's magnetic field