Earth's Structure

What is the thickest layer of the Earth?

• crust

• mantle

• outer core

• inner core

Answer explanation

The thickest layer of the Earth is the mantle, which lies between the crust and the outer core.

Since the Earth's crust lies on the mantle,

• the crust should be more dense than the mantle.

• the crust should be less dense than the mantle.

• the density of the crust should be the same as the mantle.

• the density of the crust should be the same as the outer core.

Answer explanation

The crust should be less dense than the mantle because it floats on the mantle due to differences in density.

A convection current of magma is made up of

• a rising more dense liquid and a sinking less dense liquid.

• a rising less dense liquid and sinking more dense liquid.

• liquids of the same density

• solids of the same density.

Answer explanation

The convection current of magma is made up of a rising less dense liquid and sinking more dense liquid, allowing for the movement of material within the Earth's mantle.

In general, how does the density of material in Earth's layers change with depth?

• Density increases with depth.

• Density decreases with depth.

• Density does not change with depth.

• Density increases, then decreases with depth.

Answer explanation

The correct answer is that density increases with depth in Earth's layers.

In what state, or states, is the Earth's inner core?

• liquid

• solid

• gas

• liquid and solid

Answer explanation

The Earth's inner core is in a solid state, not liquid or gas. Therefore, the correct state of the Earth's inner core is solid.

Earth's core is

• liquid

• gas

• solid

• liquid and solid

Answer explanation

Earth's core is composed of both liquid and solid materials, making it a combination of both states.

In Earth's crust, what type of rock is found under the oceans?

• granite

• basalt

• limestone

• sandstone

Answer explanation

Basalt is the type of rock found under the oceans in Earth's crust.

As depth beneath Earth's surface increases, temperature and pressure

• both increase

• both decrease

• approach zero

• stay the same

Answer explanation

As depth beneath Earth's surface increases, temperature and pressure both increase. This is due to the geothermal gradient and the weight of the overlying rock layers.

How do geologists observe Earth's interior?

• By visiting deep mines.

• Sending robots deep beneath the surface.

• By directly looking under the many layers.

• By recording and studying seismic waves.

Answer explanation

Geologists observe Earth's interior by recording and studying seismic waves, which provide valuable information about the composition and structure of the planet's layers.

Earth's magnetic field results from the spinning of the

• mantle

• crust

• core

• mesosphere

Answer explanation

Earth's magnetic field results from the spinning of the core.