Plate Tectonics

Scientists recently discovered that rocks collected from the Franklin Mountains in West Texas and rocks collected from mountains in eastern Antarctica were exactly the same age. Further research showed that the rocks were chemically and geologically the same and came from the same magma source. This discovery provides evidence of ​ (a)  

• plate tectonics
• coastal erosion
• ocean currents
• glacial melting

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112.20.b.9.A

Two oceanic plates are shown in the image.

Which type of boundary results in the spreading of the oceanic ridge?

• Convergent boundary

• Subduction boundary

• Transform boundary

• Divergent boundary

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112.20.b.9.B

This picture shows scratches in bedrock that were caused by a moving glacier. These scratches are called glacial striations.

Glacial striations in the bedrock of South Africa indicate that glaciers once moved across the African continent. The presence of glaciers on the surface of Africa is evidence that -

• the tectonic plate under Africa was closer to the South Pole at one time

• the equator was not always where it is currently located

• volcanoes did not exist until after faults occurred in Earth's crust

• the location of the North Pole and the South Pole changed

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112.20.b.9.B

A teacher asks students to make a model of a transform plate boundary. The students use blocks to represent tectonic plates and slide the blocks past each other in the directions of the arrows as shown.

Which event can the students best demonstrates with their model?

• An earthquake

• A volcanic eruption

• Formation of a rift valley

• Building up of a mountain

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112.20.b.9.B

The photograph shows mountains in the Andes range in South America.

Which statement describes the geologic process that is most likely responsible for the formation of these mountains?

• They are along a transform plate boundary that is no longer active, so erosion is creating deep valleys

• They are along a transform plate boundary in which plates are currently moving side by side, causing earthquakes and faults

• They are along a plate boundary in which plates are currently converging, causing uplift and steep slopes

• They are along plate boundary in which plates diverged in the distant past, allowing new rock to build up

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112.20.b.9.B

A mid-ocean ridge is located at the boundary of two tectonic plates. Which diagram correctly models the relative plate motion on each side of a mid-ocean ridge?

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112.20.b.9.B

Rift valleys can form when fractures in Earth's crust widen. The valley walls slowly move at a rate of only a few millimeters a year. Which of these best describes the type of tectonic activity that forms rift valleys?

• Rift valleys form where a continental plate moves under and oceanic plate

• Rift valleys form where a plate slides horizontally past another plate

• Rift valleys form where two plates move away from each other

• Rift valleys form where an oceanic plate moves under another oceanic plate

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112.20.b.9.B

The map shows some of Earht's plate tectonic boundaries.

Based on the map, volcanic activity would most likely be found at which location?

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112.20.b.9.B

The San Andreas fault is a transform fault.

Which map best predicts the likely movement of land along the fault line over thousands of years?

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112.20.b.9.B

A mid-ocean ridge separates the Pacific plate and the Nazca plate off the western coast of South America.

Which statement best describes the relative motions of the Pacific and Nazca plates?

• The Pacific and Nazca plates are both moving to the east

• The Pacific and Nazca plates are both moving to the west

• The Pacific plate is moving to the west, and the Nazca plate is moving to the east

• The Pacific plate is moving to the east, and the Nazca plate is moving to the west

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112.20.b.9.B