Name:
Period: 1 2 3 4 5 6 7
Date:
Earth’s Interior and Biosphere
What is Inside the Earth?
If you dig a hole all the way to the center of the Earth, what would you see? Would the Earth
look the same all the way through?
Scientists have wondered about the inside of our Earth. They have found ways to study it. They
use special tools to dig out samples of the Earth. Yet these samples only give us a look at the very top
part of the crust.
How do we know what the rest of the interior of the Earth is like? The model of the inside of the
Earth has mainly been developed by studying earthquake waves. Scientists have found that at certain
depths, the speed and path of seismic waves change. These changes mark the boundaries of the layer of
the Earth. Earthquakes create two types of vibrations or waves. One is called a primary wave. They are
the fastest waves and the first to get to seismograph stations. The other slower earthquake wave is
called the secondary wave. They get to the seismograph stations second.
Seismic waves speed up when they reach the bottom of the crust. This boundary is called the
Moho discontinuity. The boundary was discovered by the Yugoslavian scientist, Andrijia Mohorovicic,
who inferred that seismic waves speed up because they’re passing through a denser layer of rock.
Primary and secondary waves slow down when they hit lower section of the crust and then
speed up again as they’re transmitted through the solid upper and lower mantle.
Secondary waves aren’t transmitted through liquid, so they’re stopped completely when they
hit the liquid outer core. Primary waves are slowed and deflected but not stopped by the liquid outer
core. The primary waves again speed up as they travel though the solid inner core.
Using this informations scientists have been able to devolve the model of the Earths’ interior.
You will draw and color this model later. The layers of this model are described next.
Earth’s Layers:
At the very center of the Earth is the inner core. The inner core is solid and is composed of very
dense iron and nickel. Pressure from the layers above the inner core causes the iron and nickel to be
solid. The inner core is as hot as the surface of the sun.
Above the solid inner core lies the liquid outer core. Like the inner core, the outer core is also
made of iron and nickel.
The mantle is the largest layer inside the earth, lying directly above the outer core. It is made
mostly of silicon, oxygen, magnesium, and iron. The rock material in the upper mantle is described as
plastic-like. It has characteristics of a solid, but also flows like a liquid when under pressure.
The outer most layer of the Earth is the crust, similar in comparison to the thickness of an apple
skin to the rest of the apple, the crust is relatively that thick compared to the rest of the Earth.
When Earth was just starting to form it was a huge, hot ball of molten rock. Gradually the lighter
materials, Silicon, Aluminum, Magnesium and Oxygen rose to the surface and cooled to form the crust.
This is demonstrated by observing oil and water after they are shaken up.
The crust varies in thickness. It is greater than 60 kilometers in some mountains, but less than 5
kilometers thick under the ocean. Even our deepest holes we have drilled in the surface of the Earth
have not gone completely though the crust. For the most part they have not even come close to going
all the way through the crust.
What is Outside the Earth?
The Earth’s atmosphere is the first layer encountered when investigating what is outside the
earth. The atmosphere is actually composed of four layers: the thermosphere, the mesosphere, the
stratosphere, and the troposphere. The troposphere makes up 90% of the mass of the atmosphere. The
atmosphere is the least dense layer of the earth. The atmosphere is composed of 78% nitrogen, 21%
oxygen and 1% other gases.
The second layer encountered when investigating Earth is water. Water does not cover Earth’s
entire surface, but covers approximately three-fourths of it. Water is one of the few molecule that is
found in all three states (solid, liquid, and gas), on earth. Water is more dense than the atmosphere
(although water is found in the atmosphere as gas), but less dense than crust and interior layers. (Some
water is found in the crust and interior.) Although there is a lot of water on Earth, only a small fraction is
available for drinking.
Questions:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Which interior layer is the thickest?
Which interior layer is the thinnest?
On which layer do we live on?
Which layer of the biosphere do we live on?
Which interior layer is the hottest?
Which layer is less dense than the crust, more dense the atmosphere?
What layer(s) has melted material?
Which interior layer is the densest?
Name the layer between the crust and outer core.
What did we use to help us develop the model of the interior of the Earth?
True or False:
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
Every layer of the Earth is the same thickness.
We know what the layers of the earth are like because we’ve seen them.
The atmosphere is actually composed of four layers
The least dense part of the atmosphere is near the crust.
Water is more dense than the crust
The atmosphere is mainly made up oxygen
Pressure is greatest in the inner core.
The crust is the least dense of all the interior layers
The troposphere makes up 90% of the mass of the atmosphere.
The crust is the coolest of the interior layer of the Earth.
Name:
Period: 1 2 3 4 5 6 7
Date:
Drawing of Earth’s Interior Instructions
Directions:
You will be creating a scaled drawing of the planet Earth and all of its various layers. Use the
information below to create your drawing.
Needed Labels on every layer:
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Most dense to least dense
Actual depths/distances
Composition
Phase of matter
Actual Distances:
0-60 km: Crust
60-2,890 km: Mantle
2,890-5,150 km: Outer Core
5,150-6,378: Inner Core
Adjusted Distances For your Drawing:
Crust: .25 cm thick
Mantle: 7.5 cm thick
Outer core: 6 cm thick
Inner core: 3.2 cm thick
Diameter of Earth: 34 centimeters
Radius of Earth: 17 centimeters
Extra Information:
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Include both water and the air (atmosphere) in your drawing.
Your picture must be completely colored. The color of each layer should match what the
actual layer looks like
Water should cover approximately three-fourths (3/4) of the Earth
Take your time! Your drawing should represent your very best work.