Page 162 - Science Course 2 (Book 2)

Mo11-L5b: Evidence Supporting Seaf oor Spreading

Minerals in fresh lava record Earth’s magnetic
signature.

Scientists studied magnetic minerals in rocks from
the seaf oor using a magnetometer to measure and
record the magnetic signature.

They iscovered parallel manetic stripes on either
side of the mid-ocean ridge.
S
Each pair of stripes has a similar composition, age,
and magnetic character.
N
The pairs of magnetic stripes conf rm that the ocean
crust formed at mid-ocean ridges is carried away
from the center of the ridges in opposite directions.
Normal magnetic f eld

Volcanic rock on the seaf oor contains iron-rich Seaf oor Spreading Theory
minerals that are magnetic.

Magnetic minerals in cooling lava from the
mid-ocean ridge record the direction of Earth’s
magnetic f eld.

Other measurements made on the seaf oor conf rm
seaf oor spreading.

Measuring the amount of thermal energy leaving the
Earth shows that more thermal energy leaves Earth
near mid-ocean ridges than is released from beneath
the abyssal plains.
Scientists have discovered parallel patterns in the
magnetic signature of rocks on either side of a Sediment collected from the seaf oor can be dated
mid-ocean ridge. to show that the sediment closest to the mid-ocean
ridge is younger than the sediment farther away
from the ridge.

Reversed Normal
Key Concept

Evidence Supporting Seaf oor Spreading

What evidence is used to support seaf oor
spreading?

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