"The Spherical Structure of the Earth" Earth in the Universe PPT courseware

"The Spherical Structure of the Earth" Earth in the Universe PPT courseware

Part One: Explanation of Curriculum Standards

1. Combined with the schematic diagram, describe the propagation characteristics of seismic waves and their application in dividing the earth's inner circles. (comprehensive thinking)

2. Use the schematic diagram to explain the division and characteristics of the earth's internal spheres, and analyze the composition of the lithosphere. (comprehensive thinking)

3. Name the composition and characteristics of the earth’s outer sphere.

The Earth’s Spherical Structure PPT, Part 2: Preview of New Knowledge

1. The Earth’s Internal Sphere Structure

1.Seismic waves

(1) Concept: When an earthquake occurs, the underground rocks are strongly impacted, producing elastic vibrations that propagate around in the form of waves. This elastic wave is called a seismic wave.

(2)Characteristics

(3) Wave speed changes

2. Circle division

(1) Basis: Changes in the propagation speed of seismic waves in the interior of the earth.

(2) Interface: C in the figure is the Moho interface, and D is the Gutenberg interface.

(3) Circle layers: from the inside to the outside, E+F is the core, G is the mantle, and H is the crust.

(4) Lithosphere: The crust and the top of the upper mantle (above the asthenosphere) are composed of hard rocks, collectively called the lithosphere.

Reminder

The difference and connection between the earth's crust and lithosphere

The crust is located above the Moho interface and is a thin, hard shell composed of rock on the earth's surface. The lithosphere is different from the earth's crust. The lithosphere includes the earth's crust and the top of the upper mantle (the part above the asthenosphere).

2. The outer structure of the earth

1.Atmosphere

(1) Composition: A complex system composed of gases and suspended substances. The main components are nitrogen and oxygen. It is an important part of the natural environment.

(2) Significance: It moderates the temperature changes on the earth; provides oxygen necessary for biological survival; weather phenomena in the atmosphere are closely related to human beings.

2. Hydrosphere

(1) Composition: It is a general term for various forms of water bodies on the surface and near the surface. Its main body is the ocean, and it also includes rivers, lakes, swamps, glaciers, groundwater, etc. on land.

(2) Significance: It plays a very important role in the migration of matter and energy conversion on the earth's surface.

(3) Characteristics: A continuous but irregular circle composed of water bodies on the earth's surface.

3. Biosphere

(1) Concept: It is the general term for organisms on the earth’s surface.

(2) Scope: Concentrated in the thin contact zone between the atmosphere, hydrosphere and lithosphere.

(3) Significance: Promote solar energy conversion; change the composition of the atmosphere and hydrosphere; transform the surface morphology.

Earth's Spherical Structure PPT, Part 3: Autonomous Detection

1. Judgment of right and wrong

(1) When an earthquake occurs, people in the water feel the same as people on land. ()

(2) The lithosphere is the earth’s crust. ()

(3) The propagation speed of seismic waves changes significantly at 33 kilometers. ()

(4) The hydrosphere penetrates into the lithosphere. ()

(5) The artificial earth satellite has broken away from the outer circle of the earth. ()

Answer(1)×　(2)×　(3)×　(4)√　(5)×

The propagation speed of seismic waves in different media is different. Scientists use this principle to explore the internal structure of the earth. Complete questions 2~3 accordingly.

2. Scientists have discovered that when seismic waves propagate inside the earth, shear waves completely disappear at a depth of about 2,900 kilometers from the ground, and the propagation speed of longitudinal waves also suddenly decreases. This explains()

A. There is magma inside the earth

B. The temperature changes obviously in the upper and lower layers at this depth

C. The thickness of continental crust and oceanic crust is different

D. There is a big difference in the material composition of the upper and lower layers at this depth

3. People often use seismic waves in production activities ()

A. Transmit sound signals

B. Conduct geological prospecting

C. Investigate crop pests

D. Measure the height of the mountain

Analyzing question 2, in different media, the propagation speed of seismic waves is different, and shear waves can only propagate through solids. Therefore, according to the change of wave speed at 2,900 kilometers underground, it can be seen that there are large differences in the material composition of the upper and lower layers there. Question 3: If there are mineral resources somewhere underground, then its material composition must be different from that of the surrounding areas, which will cause abnormal changes in seismic wave speed.

Answer 2.D　3.B

The Earth’s Spherical Structure PPT, Part 4 Content: Classroom Exploration

How are the Earth's inner circles divided? What are their characteristics?

Question exploration

As the saying goes, "It's easy to go to heaven, but there's no way to enter the earth." Exploring the inner circles of the earth has always been the focus of human attention. Suppose you are on a scientific expedition through the center of the earth in a mini car that can withstand high temperatures and pressures and can penetrate hard rocks. If the on-board instruments and various sensors on the car record what they see along the way, the on-board computer uses big data to analyze the material composition of each layer.

Explore with materials:

(1) What are the main components of the earth’s crust recorded by instruments?

(2) There is a molten layer called the asthenosphere found in the mantle. Is the asthenosphere located in the upper part of the upper mantle, or at the top of the upper mantle? Why do some people think it is the main source of magma?

Tips (1) The earth’s crust is mainly composed of rocks.

(2) The asthenosphere is located in the upper part of the upper mantle. Because the heat accumulated by the decay of radioactive elements there may keep the rock in a molten state, some people believe that it is the main source of magma.

Lectures by famous teachers

1. Illustration of the division of the earth’s inner circles

Taking the Moho interface and the Gutenberg interface as boundaries, the interior of the earth can be divided into three layers: the crust, the mantle and the core.

The lithosphere includes not only the crust, but also the top of the upper mantle (the part above the asthenosphere).

2. Summary of the main characteristics of each sphere inside the earth

Skills induction

Interpretation skills of the earth’s internal circle division map

Types of information that can be extracted: types of seismic waves; Moho interface; Gutenberg interface; structure of the Earth's inner sphere.

(1) Judgment of transverse waves (S waves) and longitudinal waves (P waves). Transverse waves propagate slowly and can only propagate in solids; longitudinal waves propagate fast and can propagate in all three states: solid, liquid, and gas.

(2) Judgment of Moho interface. At an average of 33 kilometers underground (land part), the propagation speed of both transverse and longitudinal waves suddenly increases - the discontinuity (Moho interface), which is the interface between the crust and the mantle.

(3) Judgment of Gutenberg interface. At 2,900 kilometers underground, the transverse waves suddenly disappear, and the propagation speed of the longitudinal waves suddenly drops - the discontinuity (Gutenberg interface), which is the interface between the mantle and the core.

(4) The division of the earth’s inner circles. According to the Moho interface and the Gutenberg interface, the interior of the earth is divided into the crust, mantle and core.

(5) Judgment of the material state of the Earth’s inner sphere. The state of matter can be determined based on the propagation of seismic waves.

The Earth’s Spherical Structure PPT, Part 5: In-person Testing

1. The basis for dividing the earth’s internal circles is ()

A. Changes in seismic wave speed B. Temperature changes

C. Internal pressure changes D. Material composition

Analysis Based on the difference in the speed of seismic waves propagating in different media, the interior of the earth can be divided into layers.

Answer A

Read the seismic wave velocity and the Earth's internal structure diagram, and complete questions 2 to 3.

2. Regarding the description of seismic waves, the correct statement is ()

A. S waves can propagate through solids, liquids, and gases

B. P waves can propagate through solids, liquids, and gases, and the speed is slow

C. When an earthquake occurs on the seabed of a certain sea area, the ships located in the sea area are first affected by the P wave and then the S wave.

D. People often use seismic waves for geological prospecting in production activities, such as oil exploration.

3. Which of the following statements is correct ()

A. ① The upper and lower sides are the mantle and core respectively.

B.②The upper and lower sides are the mantle and crust respectively.

C. The lithosphere refers to the part above the ① surface

D.② The following parts are divided into outer core and inner core

To analyze question 2, people often use seismic waves for geological prospecting, such as oil exploration, in production activities. Seismic waves are divided into longitudinal waves (P waves) and transverse waves (S waves). Longitudinal waves propagate faster and can propagate through solids, liquids and gases; transverse waves propagate slower and can only propagate through solids. When an earthquake occurs on the seafloor, people in the ocean can only be affected by longitudinal waves. Question 3: In the figure, ① is the Moho interface, with the upper and lower sides of it being the crust and mantle respectively; ② is the Gutenberg interface, with the upper and lower sides of it being the mantle and core respectively; the lithosphere refers to the crust and the mantle The top of the upper mantle (above the asthenosphere) is composed of hard rock; below the Gutenberg interface is the core, which is divided into an outer core and an inner core.

Answer 2.D　3.D

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