"The Earth's Interior" PPT

Hunan Education Edition fifth grade science volume 1, the interior of the earth PPT

Part One: Guidance

Scientists have long wanted to drill holes to detect the internal structure of the earth. Unfortunately, so far, humans have only been able to drill holes to a depth of 14 kilometers. If a cooked egg is compared to the earth, even the eggshell has not been drilled through. Woolen cloth!

But scientists still use other methods to explore some secrets inside the earth: they guessed it through seismic waves generated during earthquakes and nuclear tests - seismic waves propagate faster in hard rocks and slower in softer rocks.

Based on this, scientists divide the interior of the earth into different layers. They call the thin layer on the surface of the earth the crust, which is mainly composed of various rocks; the central part of the earth is called the core; the layer between the crust and the core is called the earth's core. The part is called the mantle.

The Earth's Interior PPT, Part 2: The Earth's Inner Sphere

1. The inner sphere of the earth:

(1) Basis for classification: The material structure of the Earth's interior is judged based on factors such as changes in the speed of seismic waves propagating inside the Earth's interior, thereby dividing the Earth's internal circles.

Seismic waves are divided into longitudinal waves and transverse waves. Longitudinal waves can propagate in solids, liquids and gases; transverse waves can only propagate in solids. Longitudinal waves travel faster than transverse waves. Longitudinal and transverse waves propagate at different speeds in different media.

(2) Division of the Earth’s inner circles:

Based on the velocity changes of seismic waves on the Moho and Gutenberg surfaces, the interior of the Earth is divided into three layers.

1. The outermost layer of the earth’s inner circle—the crust

Thickness difference:

The continent is thick, the ocean is thin - the difference between sea and land

Thick mountains and thin plains - differences in landforms

Ridges are thick, trenches are thin - depth difference

Thick at high places, thin at low places - altitude difference

2. The middle layer of the Earth’s inner sphere—the mantle

The mantle boundary is between the Moho surface and the Gutenberg surface and is 2900km thick. The mantle is divided into upper mantle and lower mantle. There is an asthenosphere at the top of the upper mantle (generally considered the origin of magma). The part of the mantle and crust above the asthenosphere is composed of the lithosphere.

3. The innermost layer of the Earth’s inner circle—the Earth’s core

Scope: The core part below the Gutenberg surface

Ingredients: Iron and Nickel

State: The outer core is in a liquid or molten state, and the inner core is in a solid state (now it is generally considered that the inner core is in a solid state)

The Earth’s Interior PPT, Part 3: Practice

1. Fill in:

1. The earth can be divided into three layers from the surface to the center, namely ______, ______, and ______.

2. The internal structure of the Earth is like a hard-boiled egg. The shell is equivalent to the ______ of the Earth, the albumen is equivalent to the ______ of the Earth, and the yolk is equivalent to the ______ of the Earth.

3. ______ is the core part of the Earth with a temperature of about 4700 degrees Celsius.

two. Be a good little judge:

1. The thickness of the earth's crust is different in different parts of the earth. The ocean part is thin and the land part is thick. ( )

2. Scientists can use seismic waves to explore the internal conditions of the earth. ( )

3. The mantle is the outermost layer of the Earth and is made of solid rock. ( )

4. The mantle and core are mainly composed of iron, so iron on the earth is inexhaustible. ( )

3. Choose carefully:

1. Beneath the mantle is _______, which is the core of the Earth.

A. Earth's crust B. Earth's core c. center of earth

2. The Earth's crust is the outermost layer of the Earth and is made of _______.

A. Rock b. sand c. soil

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