Kinds of Crust Flashcards
What is the earth’s crust primarily composed of?
different kinds of rocks like igneous, sedimentary, and metamorphic
What determines the thickness of the earth’s crust?
depends on location, thickest in mountain regions and thinnest along the ocean floor
Average density of earth’s crust?
2.8 g/cm3
What are the two kinds of crust found in the earth’s lithosphere?
The two kinds of crust are continental crust and oceanic crust.
Describe the composition of the continental crust.
The continental crust is composed mostly of granite
Explain the composition of oceanic crust.
The oceanic crust consists primarily of basaltic volcanic lava rock
Thickness of continental crust compare to oceanic crust
Continental crusts range from 10 to 70 kilometers thick, while oceanic crusts measure about 7 kilometers thick.
Age difference between oceanic and continental crust
Oceanic crust is younger, with the oldest age around 200 million years, compared to the four-billion-year-old continental crust.
What happens when oceanic crust encounters continental crust?
Oceanic crust is pushed down due to the subduction process when it encounters continental crust.
What portion of the Earth’s surface is underlain by continental crust?
About 40% of the Earth’s surface is underlain by continental crust.
Why is the continental crust called “sial”?
Because it is rich in aluminum and silicates
What is the term for the uppermost oceanic portion of tectonic plates?
oceanic crust or “sima”
What geological features are formed by the earth’s crust?
(8) (MVTROFET)
Mountains, volcanoes, trenches, rift valleys, oceanic ridges, fault systems, earthquakes, and tsunamis.
How is the movement of tectonic plates related to earthquakes and volcanoes?
Earthquakes and volcanoes are direct results of the movement of tectonic plates at fault lines.
What is the primary cause of earthquakes and volcanoes?
Movement of tectonic plates
