Earth’s crust is continually reshaped by volcanism, erosion, and movements of continents. This lesson introduces the main rock types in the crust and explains how geological processes transform rock over time.
Earth is geologically active: processes within and upon the planet continually alter its surface. Volcanic eruptions bring material from inside Earth to the surface, while erosion wears down rocks and transports their fragments. Large-scale geological activity can also move and reshape continents.
All flashcards
What is plate tectonics?
The theory that slow motions within Earth's mantle move large segments of the crust.
What is primitive rock?
Material that has largely escaped chemical modification by heating and preserves clues about the planetary system's original material.
How does a fault-related earthquake occur?
Stress builds while parts of a fault are locked by friction, then is released when the fault slips.
What is a mantle hot spot?
A region of rising heat that can produce volcanoes away from plate boundaries.
How do metamorphic rocks form?
Heat or pressure physically or chemically changes existing igneous or sedimentary rock.
Quiz questions
How does sedimentary rock commonly form?Answer: Deposited rock fragments or shells become cemented together without melting.
How does mantle convection help move tectonic plates?Answer: Warmer mantle material rises while cooler material slowly sinks.
What commonly happens at an oceanic rift zone?Answer: Basaltic material rises, cools, and forms new oceanic crust.
What occurs at a subduction zone?Answer: One plate, commonly oceanic, descends beneath another and is recycled into the mantle.
Why can sudden movement along a fault cause an earthquake?Answer: Sudden slip releases stress that built up while friction locked part of the fault.
Based on Astronomy 2e by Andrew Fraknoi, David Morrison, Sidney Wolff (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.