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Structure of the Earth
Location-Learning Center
Send students outside to Learning Center picnic tables for next station
In this station:
1) Structure of the Earth & Plate Tectonics
-Summarize the structure of the earth, including the layers, the mantle and core
based on the relative position, composition and density.
-Explain how crustal plates and ocean basins are formed, move and interact
using earthquakes, heat flow and volcanoes to reflect forces within the earth.
-Do the density lab to create better understanding of the layers of earth
Earth
There are huge landmasses on Earth. These land masses are made out of rock plates that float across
the surface. They are called tectonic plates. Those plates float on the mantle. The mantle is an area
between the core and the crust. The mantle is basically filled with molten rock. It is kept at a liquid state
because of the energy given off by the center (core) of the Earth.
Composition of the Earth
Crust
The crust is a thin outer layer of the earth where
we live. It varies from 5k to 70km thick. The part
that we live on is the continental crust whereas the
part that is in the ocean is the oceanic crust
Mantle
The second layer is the mantle. The mantle is much
thicker than the crust.
Together they (crust and mantle) are combined to
form the tectonic plates. These plates move very
slowly. Where the plates touch is called a fault. There are three main boundaries for tectonic plates. A
convergent boundary is where two plates collide into one another. This is there mountains and
volcanoes are formed. A divergent boundary is where two plates move away from one another. An
example of this is the Mid-Atlantic Ridge in the Atlantic Ocean. This is where new crust is formed. The
third type of boundary is a transform boundary. This is where 2 plates move horizontal to one another.
This causes earthquakes
Outer Core
The outer core is made up of iron and nickel and is extremely hot (4400 to 5000+ degrees C). This causes
the iron and nickel to remain in liquid form.
Inner Core
The inner core is made up of iron and nickel just like the outer core. However, since it is so deep within
the earth it is under immense pressure. Even though it is just as hot as the outer core, the pressure
causes the iron an nickel to remain solid. The inner core is the hottest part of the earth at over 5000
degrees C. That is about as hot as the surface of the sun.
Plate Tectonics
The earth’s solid crust is composed of separate sections (plates) that constantly move on a partially
molten layer of upper mantel. Major geologic events such as volcanic eruptions result from these plates.
The place where two plates meet is called a boundary.
The two types of plates are continental and oceanic. Continental plates are thicker but less dense than
oceanic plates. This means when the two meet the oceanic plate will always subduct under the
We have 3 major types of plate boundaries; Divergent, Convergent and Transform
Divergent boundaries are places where the lithospheric plates are moving apart. Most divergent
boundaries have mid-ocean ridges (2) with deep rift valleys (3) along their entire length. Rising
convection currents in the asthenosphere (1) carry molten rock into the rift valleys, where new rocks
solidify, forcing the ocean floor to spread.
Convergent boundaries are when one plate collides with another and slides beneath it. A deep sea
trench (7) is formed at the subduction boundary (8). When this trench is formed by the convergence of
two ocean plates, it is bordered by a chain of volcanic islands on the overriding ocean plate. When an
ocean plate (11) converges with a continental plate, the denser ocean plate is subducted beneath the
continental plate and the deep-sea trench is bordered by mountains and volcanoes (9) on the
continental plate.
Transform boundaries are where one plate is sliding past another horizontally, causing little to no
subduction. (The left side of this model illustrates a type of transform boundary.) However, because the
edges are rough, they catch on one another, allowing stress to build up. When this stress is released
suddenly, earthquakes may occur.
Density lab
Explain to the class that they are going to simulate the layers of the earth with different liquids. Explain
that due to different densities the liquid layers and the solid layers of the earth do not combine. So what
is density? The density of a material is its mass per unit volume. Things with less density will float and
things with a higher density will sink. So which do you think is more dense, the inner core or the outer
core? Inner because it sits underneath of the outer core. The inner core is the densest layer of the earth.
Materials
Rubbing alcohol
Vegetable oil
Water
Light corn syrup
Food coloring
Mason jars
1. Divide the class into 4 equal groups.
2. Give each group a mason jar, rubbing alcohol, vegetable oil, water, light corn syrup, and food
coloring.
3. Tell them that based on those 4 items (alcohol, oil water and corn syrup) they need to decided
what the order from most dense to less dense is. Do not mix anything together yet. They must
be approved by the teacher first.
a. Rubbing alcohol – crust
least dense
b. Vegetable oil – mantle
c. Water – outer core
d. Corn syrup – inner core
most dense
4. When they have the correct order from most to least
dense they may start combining their layers. Make
sure that the densest goes in first. Allow them to only
pour 2 inches per layer. Make sure to pour the layers
in slowly as to not mix with the layer underneath.
**Note: They may use food coloring to color the
alcohol and water. If coloring the alcohol, make sure
they pour the amount into a cup and mix the colors
before adding it to the mason jar.
When cleaning up pour the mixture in the sink while running
hot water. Rinse out the mason jars.