Inside the Restless Earth – Ch. 4 Plate Tectonics
Section 1 - Inside the Earth
Name________________
A. The Composition of the Earth (pg 88-91) - sketch and label the following parts of the Earth
1. Crust
a. Composition- rock
b. Thickness- 5 to 100 KM, thinnest
c. Ability to flow-solid
The Three Layers of the Earth
See page 89 in Restless Earth book
2. Mantle
a. Composition-molten rock
b. Thickness- 2900 KM
c. Ability to flow- very slowly
3. Core
a. Composition-iron and nickel
b. Thickness- 6856 km in diameter
c. Ability to flowi.
outer core - liquid
ii.
inner core - solid
B. Tectonic Plates (pg 93)
a. Tip of the iceberg -Differences between oceanic and continental crust are …………(discuss
thickness and density)
Continental crust stands higher than oceanic crust because it is thicker and less dense.
Continental crust “floats” on the asthenosphere.
C. Mapping the Earth’s Interior (pg 94)
a. Seismic waves are ……vibrations that travel through the Earth. Caused by earthquakes
b. Seismic waves travel at different___speeds_______ depending on…. the density and
strength of the material they travel through. Seismologists use these speeds to calculate the
density and thickness of Earths layers.
Section 2 - Restless Continents
A. Wegener’s Theory (pg 95-97)
1. Continental Drift is ….the theory that continents can drift apart from one another and have
done in the past.
2. Evidence Supporting the Theory
a. Fossils of the same plant and animal species
b. Similar type of rocks
c. Glacier grooves
d. Mid Ocean ridges
e. Continents fit together like puzzle pieces
3. Theory not accepted because… how could any force of nature be strong enough to move entire
continents.
B. Pangaea is….All of the continents joined together in a single landmass as one continent.
C. Sea-floor Spreading (pg 97)
a. A mid-ocean ridge is…..a place where sea floor spreading takes place.
b. The gap in the sea floor……allows magma to rise and fill in the gap.
c. Age of crust increases as….. you move farther from the gap in the sea floor.
Section 3 - The Theory of Plate Tectonics
A. 3 Possible Causes of Plate Tectonic motion (pg 99-figure 13)
a. Ridge push – Oceanic plate slides down the lithosphere asthenosphere boundary
b. Slab pull- The edge of the oceanic plate sinks and pulls the rest of the plate with it.
c. Convection – Hot material from deep in Earth rises while cooler material near the surface
sinks causing circular motion that drags plates sideways.
B. Tectonic Plate Boundaries (pg 100-101) –Draw and label a diagram of each of the following
boundaries. Use arrows to show direction plate is moving.
Explain what happens (forms) at each of these boundaries.
1. Convergent
a. Continental/Oceanic- Oceanic plate slides beneath the continental crust. Subduction zone.
b. Oceanic/Oceanic – One plate slides under another
c. Continental/Continental – Crust is pushed upward forming mountains.
2. Divergent – Oceanic plates move apart. Sea floor spreading occurs here.
3. Transform- Plates slide against each other. Earthquakes may occur here.
C. Tracking Tectonic Plate Motion (pg 102)
a. Tectonic movement - Plates movement is measured in… Centimeters per year.