EASC Intro to Earth and Earth's Interior

What layers of Earth are included in the model students are expected to describe?

Inner core, outer core, mantle, and crust.

What is the average density of Earth?

5.51 grams per cubic centimeter.

What is the Mohorovičić discontinuity commonly known as?

Moho.

What are the two types of seismic waves that travel through Earth's interior?

P-waves (compressional waves) and S-waves (shear waves).

What characterizes the oceanic crust?

It is thin (about 7-10 km thick), young (less than 200 million years old), and composed of mafic silicates like basalt.

What is the main composition of the Earth's mantle?

Ultramafic silicates, primarily peridotite.

Why is Earth's inner core solid despite being extremely hot?

The pressure from the rest of the planet is so great that the iron cannot melt.

What are the mechanical properties of the lithosphere?

It is solid, strong, and rigid, and includes the crust and the uppermost mantle.

What role does the outer core play in Earth's properties?

It creates Earth's magnetic field through its flow driven by heat loss and Earth's rotation.

How thick is the Earth's crust under the continental regions compared to the oceanic regions?

Continental crust is 30-70 km thick, while oceanic crust is about 7-10 km thick.

What happens to seismic wave velocities as they move through different materials in the Earth?

Seismic waves travel at different velocities, allowing geoscientists to identify boundaries between Earth's layers.

What is the primary composition of Earth’s core?

Iron alloy, primarily composed of iron mixed with some nickel.

Describe the asthenosphere.

A solid but ‘plastic’ region below the lithosphere, characterized by its mechanical weakness and high viscosity.

What is the significance of the Kola Superdeep Borehole?

It is the deepest borehole, reaching 12,262 meters (40,230 feet) deep.

What types of rocks predominantly make up the crust?

Rocks that are primarily composed of silicates, including both granitic and mafic rocks.

How do geologists infer the presence of Earth's core?

By indirect measurements and the study of seismic wave behavior.

What process occurs in the mantle that causes material to circulate?

Convection, driven by heat from the Earth's core.

What is the approximate thickness of Earth's lower mantle?

Approximately 1,800 miles (2885 km) thick.

What does the crust serve as for humans?

It is our home and the source of all our resources.

In what way do the densities of Earth's crust and core compare?

The core is far denser than the crust, which influences the structure of Earth's interior.