What Happens at Divergent Boundaries

What Happens at Divergent Boundaries

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What happens at Mid-Ocean Ridges?

Divergent boundaries, also called spreading centers, are locations where two oceanic plates are moving apart. Due to this divergence they routinely have small earthquakes from movement and also the site of submarine volcanism or lava flows.

Multiple Choice

Divergent boundaries are the site of both earthquakes and volcanism as the two plates move apart from one another and magma rises to fill the rift.

• True

• False

Continental Rifting

Divergent boundaries can also occur between continental plates which can result in splitting a continent apart. Such an event is currently occuring in the Great Rift Valley in East Africa that is widening the Red Sea.

Multiple Choice

Continental rifting is currently occuring in

• The Himalayan Mountains

• The Mediterranean Sea

• East Africa & the Red Sea

Paleomagnetism

Earth’s magnetic field can be recorded in rocks as certain iron rich minerals (magnetite) become orientated to Earth’s magnetic field as they crystalize in volcanic rocks.

Multiple Choice

What is an iron-rich mineral that can orient to Earth’s magnetic field?

• pyrite

• magnetite

• graphite

What causes Earth's Magnetic Field?

• Movement of molten iron within Earth’s liquid outer core along with electrical currents generates Earth’s magnetic field.

• Our current magnetic polarity is called normal polarity but many times in the past it became reversed polarity in which the North magnetic pole would be located over the South pole.

Multiple Choice

Earth’s current polarity is (normal or reversed).

• normal

• reversed

How Do Magnetic Reversals Help Us Infer the Age of Rocks?

• Geoscientists have constructed a timescale of Earth’s magnetic reversals for the past 180 million years, called the geomagnetic reversal timescale.

• They can then use this timescale to determine the age of volcanic rocks.

Multiple Choice

How many magnetic reversals have occurred in the Quaternary Period?

• 3

• 5

• 9

How Do Magnetic Patterns on the Seafloor Help Us Study Plate Tectonics?

• Geoscientist discovered that the pattern of magnetic reversals captured in rock were matching on either side of the mid-ocean ridge thus proving seafloor spreading.

Multiple Choice

The age of the seafloor can be determined by analyzing the polarity of the rock and matching it with the geomagnetic reversal timescale.

• True

• False