7th Grade Unit 3

The cross section below shows a portion of Earth’s crust and upper mantle near a mid-ocean ridge.

What is the most likely cause of the geological features in this mid-ocean ridge?

• Colliding plates in the lithosphere.

• Sinking iron and magnesium in the lithosphere.

• Cooler temperatures in the mantle.

• Rising convection currents in the mantle.

Why does the oceanic crust sink beneath the continental crust at a subduction boundary?

• The oceanic crust has a greater density.

• The oceanic crust is pulled downward by Earth’s magnetic field.

• The continental crust is composed of more magnesium and iron.

• The continental crust is pulled upward by the Moon’s gravity.

The cross section below shows the location of earthquakes near a plate boundary by identifying each earthquake focus (point of origin).

What is the most likely cause of the earthquakes near this plate boundary?

• A transform fault

• A mantle hot spot

• Subduction of a crustal plate

Compared to Earth’s crust, Earth’s core is believed to be:

• Less dense, cooler, and composed of more iron.

• Less dense, cooler, and composed of more iron.

• Denser, hotter, and composed of more iron.

• Denser, cooler, composed of less iron.

Heat from deep in the Earth’s interior is transferred to its crust by which of the following?

• Conduction in the ocean.

• Convection in the mantle.

• Radiation from the solid core.

• Evaporation at mid-ocean ridges.

Which diagram best represents the type of plate movement that results in mountains?

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The diagram shows the Pacific Ring of Fire. Earthquakes and volcanic activity occur along the Ring of Fire.

Which of the following best explains why?

• It is located at the boundaries of tectonic plates.

• It is located at the boundary of deep and shallow water.

• It is located where major ocean currents meet.

• It is located where ocean temperature is the highest.

In which layer of Earth are the convection currents that directly result in tectonic plate motion found?

• Crust

• Inner Core

• Mantle

• Outer core

Convection causes large masses of rock to rise from and sink into Earth’s mantle. The main heat source for this movement is

• Where Earth’s tectonic plates are sliding past each other.

• Where magma cools slowly beneath Earth’s surface.

• Where Earth’s lithosphere is in constant, slow motion.

• Where Earth’s seafloor is spreading into deep ocean trenches.

Where are earthquakes most likely to occur?

• Where Earth’s tectonic plates are sliding past each other.

• Where magma cools slowly beneath Earth’s surface.

• Where Earth’s lithosphere is in constant, slow motion.

• Where Earth’s seafloor is spreading into deep ocean trenches.