Layers of Earth

As you go deeper into Earth, the pressure ______ and the temperature ______.

• increases, increases

• increases, decreases

• decreases, increases

• decreases, decreases

Answer explanation

As you go deeper into Earth, both pressure and temperature increase due to the weight of the overlying material and the geothermal gradient. Therefore, the correct answer is 'increases, increases'.

________ determines how the layers of the earth form.

• density

• temperature

• pressure

Answer explanation

Density is the key factor that determines how the layers of the Earth form. Different materials have varying densities, leading to the stratification of layers, with denser materials sinking and lighter ones rising.

Which layer is the densest?

• crust

• mantle

• core

Answer explanation

The core is the densest layer of the Earth, primarily composed of iron and nickel, resulting in a high density compared to the crust and mantle, which are less dense and made up of lighter materials.

Which physical layer is made of the crust and the rigid upper part of the mantle?

• lithosphere

• asthenosphere

• mesosphere

Answer explanation

The lithosphere is the outermost layer of the Earth, consisting of the crust and the rigid upper part of the mantle. It is distinct from the asthenosphere, which is more ductile, and the mesosphere, which is deeper and denser.

Which is the least dense layer?

• crust

• lithosphere

Answer explanation

The crust is the outermost layer of the Earth and is less dense than the lithosphere, which includes the crust and the upper mantle. Therefore, the crust is the least dense layer.

Which layer is the gooey part of the upper mantle?

• lithosphere

• asthenosphere

• crust

• outer core

Answer explanation

The asthenosphere is the semi-fluid layer of the upper mantle, allowing for the movement of tectonic plates. It is often described as the 'gooey' part, unlike the rigid lithosphere above it.

Which chemical (major) layer is right above the core?

• crust

• mantle

• asthenosphere

• mesosphere

Answer explanation

The mantle is the major layer located directly above the core. It is composed of silicate rocks and extends to the crust, making it the correct answer to the question.

Which layer is composed of solid iron and nickel?

• crust

• mantle

• core

Answer explanation

The core is the innermost layer of the Earth, composed primarily of solid iron and nickel. In contrast, the crust is the outer layer, and the mantle lies between the crust and the core.

Which is the thinnest layer?

• crust

• mantle

• core

• lithosphere

Answer explanation

The crust is the outermost layer of the Earth and is significantly thinner than the mantle and core. It varies in thickness but is generally much less thick compared to the other layers, making it the thinnest layer.

Which layer is about 1/3 or 33% of Earth's mass?

• mantle

• mesosphere

• core

Answer explanation

The core makes up about 1/3 or 33% of Earth's mass, while the mantle and mesosphere are less massive. Therefore, the correct answer is the core.