How does the ocean floor preserve evidence of past magnetic reversals?
A)Magnetic particles in basalt orient with the magnetic field in force at the time the oceanic lava cooled and hardened.
B)Isotopic analysis of ocean core sediments help determine sea floor age and this can be used to infer past magnetism.
C)The ocean floor is uniformly old,preserving the Earth's 4.6 billion history.
D)Mantle hot spots are always oriented to the magnetic field.
E)The oldest oceanic crust is always found near mid-ocean ridges.As one moves out from these ridges,the crust is simultaneously younger and oriented according to the polarity at the time.

Question

Quizplus · Accepted Answer

Magnetic particles in basalt orient with the magnetic field in force at the time the oceanic lava cooled and hardened. As the lava cools and solidifies, iron-rich minerals in it align with the direction of Earth's magnetic field, creating a record of the direction and intensity of the magnetic field at that time. This creates a pattern of magnetic stripes on the ocean floor that provide evidence of past magnetic reversals.

How Does the Ocean Floor Preserve Evidence of Past Magnetic