Inside Earth Study Guide
Pages C52 – C57
Scientists study earthquakes to learn more about Earth.
An earthquake is a movement or vibration in the rocks that make up Earth’s crust
caused by the release of stored energy in Earth’s outer layer.
A fault is a break in Earth’s outer layer caused by the movement of rocks.
The point at which an earthquake starts is called the focus.
Scientists use an instrument called a seismograph to measure seismic waves.
The printed record made by a seismograph is called a seismogram.
Seismic waves are vibrations caused by rocks moving and breaking along faults.
The farther these waves travel away from the focus, the weaker they become.
There are different kinds of seismic waves:
I.
Primary Waves
A. called P waves
B. fastest waves
C. first to arrive at a distant point
D. travel through solids, liquids, and gasses
II. Secondary Waves
A. called S waves
B. travel slower than P waves
C. arrive later at a distant point
D. travel through solids only
III. Surface Waves
A. called L waves (long waves)
B. slowest waves
C. felt at the surface
D. cause the damage
Inside Earth Study Guide
Pages C58 – C59
Earth has four different layers. Each layer has different characteristics. The distance
from Earth’s surface to its center is about 6,400 kilometers or 4,000 miles.
Earth’s Structure
I.
Crust
A. life exists on this layer
b. Earth’s outermost layer
B. thinnest layer
C. solid rock which is thicker under continents than oceans
II. Mantle
A. layer of rock lying below the crust
B. thickest layer
C. layer is solid but rocks move or flow due to pressure and high
temperatures
III. Outer Core
A. layer between mantle and inner core
B. liquid layer
C. a molten lava composed primarily iron and nickel
D. inner core floats inside this layer
IV. Inner Core
A. solid sphere (may be solid because of extreme pressure from other layers)
B. hottest layer made of nickel and iron
C. Earth’s center (spins at different rate than rest of earth)
Essay:
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Use the attached outline to organize your essay writing.
This is expository writing: writing that informs and explains. It should be well
organized with clearly stated explanations, details, and examples.
Use transition words to make your ideas flow together smoothly.
The essay must include an appropriate 4th grade opening and closing as discussed
in class. (The opening should introduce your topic. The closing should summarize
the topic.) Both must be at least two sentences in length.
This essay should not be written in first person. Do not use pronouns.
(DO NOT WRITE: I am going to tell you…/ Now you know about ….etc.)
Layers of Earth Essay
I.
Paragraph 1 (Opening)
(Introduce topic)___________________________________________________________
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(Name the four layers)______________________________________________________
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(Explain how scientists use information gathered from seismographs after an earthquake to
learn about Earth’s layers ____________________________________________________
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II.
Paragraph 2 (Describe the crust)
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III. Paragraph 3 (Describe the mantle)
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IV.
Paragraph 4 (Describe the outer core)
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V.
Paragraph 5 (Describe the inner core)
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VI.
Closing (Tie your ideas together- summarize!)
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