STUDY GUIDE
E3.2A Describe the interior of the Earth (in terms of crust, mantle, and inner and outer cores)
http://www.youtube.com/watch?v=Q9j1xGaxYzY&feature=related
You should know-Earth is made up of layers. Each layer has unique characteristics.
CRUST: The crust is the outermost layer of Earth. This layer, on which life exists, is covered with soil, rock, and
water. Relative to the thickness of Earth’s other layers, Earth’s crust can be compared in thickness to the shell
of an EGG. The crust is thickest under the continents and thinnest under the oceans.
Thickness: 5 to 64 kilometers (varies depending on which type of crust)
State: Solid
MANTLE: The mantle is Earth’s thickest layer. About 80% of the volume of Earth is contained in Earth’s mantle,
which extends from the base of the crust to the liquid outer core. The mantle is generally considered to exist in
a solid state, although high temperatures and pressure can cause some of this solid rock to flow like an
extremely thick liquid.
Thickness: About 2900 kilometers
State: Considered solid, but has the quality of plasticity, which means the solid rock in this layer can flow like a
thick liquid
OUTER CORE: Most of the rock in Earth’s outer core is molten, which means that it acts like a hot liquid. The
outer core begins about 2900 kilometers below Earth’s surface.
Thickness: About 2250 kilometers
State: Molten liquid
INNER CORE: Earth’s inner core is incredibly dense, because it is under so much pressure. The inner core
begins at a depth of about 5150 kilometers below Earth’s surface.
Thickness: Radius is about 1300 kilometers
State: Solid
E3.2C Describe the differences between oceanic and continental crust (including density, age,
composition).
The crust covers the mantle and is the earth's hard outer shell, the surface on which we are living.
Compared to the other layers the crust is much thinner. It floats upon the softer, denser mantle. The
crust is made up of solid material but this material is not the same everywhere.
Oceanic crust:
As the name already suggests, this crust is below the oceans. There, the crust is 4-7 miles (6-11 km)
thick.
The rocks of the oceanic crust are very young compared with the rocks of the continental crust. The
rocks of the oceanic crust are not older than 200 million years. Made mostly of basalt. Basalt has a
dark, fine and gritty volcanic structure. It is formed out of very liquid lava, which cools off quickly.
The grains are so small that they are only visible under a microscope. The average density of the
oceanic crust is 3g/cm³.
Continental crust:
The earth's crust is the thickest below the continents, with an average of about 20 to 25 miles (30 to 40
km) and with a maximum of 45 miles (70 km). The continental crust is older than the oceanic crust, some
rocks are 3.8 billion years old.
The continental crust (not the surface of the earth) mainly consists of igneous rocks and is divided into
two layers. The upper part mainly consists of granite rocks, while the lower part consists of basalt and
diorite.. The average density of the continental crust is 2.7g/cm³.
http://www.youtube.com/watch?v=ifke1GsjNN0&feature=related
E3.3 Plate Tectonics Theory overview
E3.3B Explain why tectonic plates move using the concept of heat flowing through mantle convection,
coupled with the cooling and sinking of aging ocean plates that result from their increased density.
http://www.youtube.com/watch?v=uq7zlVdDaVs&feature=related
WEGENER—CONTINENTAL DRIFT—WHAT WAS HIS EVIDENCE? WHY WAS HE NOT
TAKEN SERIOUSLY?
EVOLVED INTO THEORY OF PLATE TECTONICS
The Earth’s crust and upper mantle make up the lithosphere, which is broken into large moving pieces
called tectonic plates. The plates move at velocities in units of centimeters per year as measured using the
global positioning system (GPS). Motion histories are determined with calculations that relate rate, time,
and distance of offset geologic features. Oceanic plates are created at mid-ocean ridges by magmatic
activity and cooled until they sink back into the Earth at subduction zones. At some localities, plates
slide by each other. Mountain belts are formed both by continental collision and as a result of subduction.
The outward flow of heat from Earth’s interior provides the driving energy for plate tectonics.
(CONVECTION)
E3.3A Explain how plate tectonics accounts for these features and processes –
sea floor spreading -- where plates are moving apart (DIVERGENT boundaries)
mid-ocean ridges – where plates are moving apart – this is where the molten material cools and then new
cracks open up leaving a long chain of mountains (THE LONGEST ON EARTH!) but they are under the
ocean.
subduction zones – where plates are converging or moving toward each other and one plate sinks under
another-- different types
oceanic oceanic-- one ocean plate that is older and cooler and denser sinks when up against the
younger less dense plate—even though they are both oceanic. Deep ocean trenches and island
arcs form here!! See P. 208
oceanic continental—ocean crust sinks under continental—also form deep ocean trenches and
also coastal mountains.. some of the mountains can also be volcanoes. (example Mt St. Helen)
http://www.youtube.com/watch?v=ANeH9W-HMPc&feature=related
earthquakes -- transform boundaries—plates scrape past each other (example?? St. Andreas fault)
volcanoes where continents split apart (DIVERGENT BOUNDARIES)
mountain ranges—CONTINENTAL CONTINENTAL COLLISION they are about equal density and so
they crash into each other, crumple and fold up
http://www.youtube.com/watch?v=ngV66m00UvU&feature=related