Earth's Layers - UPCAT

Flashcards based on lecture notes describing the layers of the Earth, focusing on composition, physical properties, and boundaries.

What are the two criteria used to subdivide the Earth into layers?

Composition (density) differences and physical properties

What are the two types of crust?

Continental and oceanic crust

Which type of crust is older and more buoyant?

Continental crust

What is the average thickness of the continental crust?

35 km (can be more than 70 km in mountainous regions)

What is the average composition and density of the continental crust?

Granite, with a density of 2.7 g/cm3

Which type of crust is younger and denser?

Oceanic crust

What is the average thickness of the oceanic crust?

7 km

What is the composition and density of the oceanic crust?

Basalt, with a density of 3.0 g/cm3

What percentage of the Earth's volume does the mantle comprise?

More than 80%

What is the boundary between the crust and the mantle called?

Mohorovičić discontinuity

What is the composition of the core?

Iron and nickel (Fe-Ni) alloy

What is the density of the core?

Approximately 11 g/cm3

What two layers make up the lithosphere?

The entire crust and the uppermost layer of the upper mantle

What is the average thickness of the lithosphere?

100 km (can reach up to 300 km in the thickest portions of continents)

What is the asthenosphere?

A mechanically weak layer consisting of the lower portion of the upper mantle, extending to 660 km

What is the dominant rock type in the upper mantle (asthenosphere)?

Peridotite (Mg- and Fe-rich rock)

How does the asthenosphere move?

Like a very viscous fluid

What is the mesosphere comprised of?

The lower mantle

What is the dominant rock type in the mesosphere?

Perovskite (silicate rock)

What is the state of matter of the outer core?

Liquid (melted Fe-Ni alloy)

What causes the liquid nature of the outer core?

Extremely high temperatures (more than 3000°C)

What is the flow of liquid metals in the outer core responsible for?

Earth’s magnetic field

What is the outer-inner core boundary known as?

Lehmann discontinuity

What is the state of matter of the inner core?

Solid (mostly Fe)

What are the temperatures in the inner core?

Similar to the surface of the Sun - around more than 5400°C