Characteristics and Composition of Earth's Crust

What are the two main types of Earth's crust?

• Inner and Outer

• Upper and Lower

• Oceanic and Continental

• Mantle and Core

The Earth's crust is the uppermost rigid, solid, and cold part of which layer?

• Atmosphere

• Asthenosphere

• Lithosphere

• Mantle

Oceanic crust is described as "mafic." What does this term mean?

• It is made of minerals with more metals like iron and magnesium.

• It is made of minerals with more silica and lighter elements.

• It is very thick and buoyant.

• It easily crumbles and folds.

What type of rocks primarily make up oceanic crust?

• Granite

• Sandstone

• Basalt and Gabbro

• Limestone

Which of the following is a characteristic of oceanic crust?

• Thick

• Less dense

• Cold

• Felsic

When oceanic crust is formed, it is igneous and runny. What does this characteristic cause it to do?

• It becomes very thick.

• It spreads out.

• It crumbles and folds.

• It becomes less dense.

What is the primary type of rock that makes up continental crust?

• Basalt

• Gabbro

• Granite

• Obsidian

Continental crust is described as "felsic." What does this term mean?

• It is made of minerals with more metals like iron and magnesium.

• It is made of minerals with more silica and lighter elements.

• It is very thin and dense.

• It spreads out easily when formed.

Which of the following is a characteristic of continental crust?

• Thin

• Dense

• Mafic

• Thick

When tectonic plates interact, what happens to continental crust instead of subducting?

• It melts and becomes oceanic crust.

• It spreads out and becomes thinner.

• It crumbles, folds, bends, and gets thicker.

• It becomes mafic.