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8.3 Note-taking Guide B
1. Divergent Boundary: top row: a sketch of a divergent boundary; second row: a
sentence using the term; third row: the boundary where tectonic plates move apart;
Convergent Boundary: top row: sketch of a convergent boundary; second row: a sentence
using the term; third row: the boundary where tectonic plates push together; Transform
Boundary: top row: sketch of a transform boundary; second row: a sentence using the
term; third row: where two plates scrape past each other.
2. Another name for a divergent boundary in the ocean; two plates are moving apart.
3. Mid-ocean ridges are the longest chains of mountains on Earth. Most mid-ocean
ridges have a rift valley running along their center. At the Mid-Atlantic Ridge, the North
and South American plates are moving away from the Eurasian and African plates.
4. Point A; This point is closest to the rift valley, where the rock is being formed.
5. Sample answers: Earth’s magnetic poles have switched places many times. Magnetic
minerals line up with new north/south poles. The cause is unknown. Geographic poles
remain fixed.
6. As molten rock cools and solidifies, magnetic minerals in the molten rock line up
along Earth’s current magnetic field. When the field reverses, the magnetic minerals line
up in the new direction.
7. Continents begin to split apart as a rift valley grows wider. As a rift valley grows, its
floor sinks below sea level and fills with water. An example of a filled rift valley is the
Red Sea.
8. An area of volcanic activity whose source is in the mantle; Hot spots provide a fixed
point that allows scientists to track plate speed and direction.