Chapter 12 Section 3 Earth’s Interior

Chapter 12 Section 3 – What You’ll Learn - page 370 Before you read - write the reading’s objectives in this space: 1 – _____________________________________________________________________________________________ 2 – _____________________________________________ ________________________________________________ ________________________________________________ ________________________________________________

Chapter 12 Section 3 – What You’ll Learn - page 363 Before you read - write the reading’s objectives in this space: 1 – Explain how geologists infer the structure of Earth’s deep interior. 2 – Describe Earth’s internal structure and composition.

How do scientists learn about Earth’s interior? Use seismic waves to gather data about Earth’s interior – kind of like a sonogram on humans! Label the diagram to the right with the general name and thickness: 5 Earth’s Interior Video 1.5 min 1

How do scientists learn about Earth’s interior? Use seismic waves to gather data about Earth’s interior – kind of like a sonogram on humans! Label the diagram to the right with the general name and thickness: Inner core 1220 km Outer core 2250 km Mantle 2900 km Asthenoshphere 200 km 5 Lithosphere 100 km Earth’s Interior Video 1.5 min

Recall what is refraction? ___________________ __________________________________________ What is a discontinuity? ___________________________________________ Andrija Mohorovičić was the first in the world to establish, on the basis of seismic waves, a surface of velocity discontinuity that separates the crust of the Earth from the mantle and which was named the Mohorovičić Discontinuity, also known as the Moho, in his honor. 2

Recall what is refraction? The bending of waves due to a change in density. What is a discontinuity? A boundary that marks a density change between Earth’s layers. The Mohorovičić discontinuity separates Earth’s crust from the mantel. Andrija Mohorovičić was the first in the world to establish, on the basis of seismic waves, a surface of velocity discontinuity that separates the crust of the Earth from the mantle and which was named the Mohorovičić Discontinuity, also known as the Moho, in his honor.

What is the shadow zone? ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ 3

What is the shadow zone? A dead zone between 105 and 140 degrees from the focus of an earthquake, little or no seismic waves can be detected. This is because primary waves (P-waves) are refracted by the Earth's core and secondary waves (S-waves) are stopped by the core.

Shadow Zones Earth’s Interior 3 3

Composition of Earth’s Layers describe the following: The crust and uppermost mantle (The lithosphere) _______ __________________________________________ __________________________________________ The asthenosphere _____________________________ __________________________________________ __________________________________________ Mantle below the asthenosphere __________________ __________________________________________ The cores ___________________________________ __________________________________________ __________________________________________ 4

Composition of Earth’s Layers describe the following: The crust and uppermost mantle (The lithosphere) are made of rocky material—mostly silicates. The asthenosphere is a weaker, plastic like layer upon which Earth’s lithospheric plates move. Mantle below the asthenosphere also is composed of silicates. The cores are made mostly of metallic material iron and nickel.

How do astronomers think the Earth formed? ____________________ __________________________ __________________________ __________________________ __________________________ __________________________ __________________________ __________________________ __________________________ __________________________ 5

How do astronomers think the Earth formed? From meteor-like material forced together by gravity and melted. The densest of this material settled toward the core and the lower density materials settled outward.

Section Check Question 1 What is Earth’s core made of?_____________________________________ _______________________________________ _______________________________________ 6

Section Check Question 1 What is Earth’s core made of? Answer Earth’s core is primarily made of metallic material such as iron and nickel.

Section Check Question 2 Earth’s internal layers become _______ with depth. A. cooler B. darker C. denser D. lighter 7

Section Check Question 2 Earth’s internal layers become _______ with depth. A. cooler B. darker C. denser D. lighter The answer is C. Answer

Section Check Question 3 What can’t S-waves penetrate the liquid outer core? ________________________________________ ________________________________________ 8

Section Check Question 3 What can’t S-waves penetrate the liquid outer core? Answer S-waves only travel through solids. This suggests that the outer core is in a liquid state.