Download E.S. Ch. 3 Study Guide

Science Study Guide: E.S. Chapter 3: Plate Tectonics
Continent—is a large landmass.
Boundary—is the point or line where one region ends and another begins.
Crust—is the outer layer of Earth.
Mid- at or near the middle
Sub- below, beneath, under
Wegener’s hypothesis was that all the continents were once joined together in a single
landmass and have since drifted apart.
Continental Drift— Wegener’s idea; the continents slowly move over Earth’s Surface.
Pangaea—The Super Continent.
Fossil—is any trace of an ancient organism that has been preserved in rock.
Evidence that supports the continental drift hypothesis includes fossils, geology, climate, and
“puzzle pieces” (continents look like they fit together)
Glossopteris- was a fernlike plant that lived 250 million years ago. Because it was found on
many different continents, it helped prove that Pangaea existed.
Wegener stated that as continent moves toward the equator, its climate gets warmer.
Mid-ocean ridges—Long, undersea mountain chains where new ocean floor is produced.
(They are divergent plate boundaries.)
Sonar- is a device that uses sound waves to measure the distance to an object.
Sea-Floor Spreading—is the process by which molten material adds new oceanic crust to the
ocean floor.
The evidence that geologists have found for sea-floor spreading are: Evidence from Ocean
Material (pillow lava), Magnetic Stripes, Drilling samples.
Deep ocean trenches— Underwater canyons. They are deep valleys along the ocean floor
where oceanic crust slowly sinks toward the mantle.
Subduction- is the process by which the ocean floor sinks beneath a deep ocean trench and
back into the mantle again.
Because of subduction and sea-floor spreading, the ocean floor is renewed about every 200
million years.
The size of the Earth’s oceans is determined by how fast new crust is being created at midocean ridges and how fast old crust is being swallowed up at deep sea trenches.
The Atlantic Ocean is expanding.
Plate- A section of the lithosphere that slowly moves over the asthenosphere, carrying pieces
of continental and oceanic crust.
The 3 types of tectonic plate boundaries:
Divergent boundary- is when plates move apart. Hot molten rock from the mantle rises,
cools, and causes the floor to spread, causing new rock to form. Examples: Mid-Atlantic
Ridge and Iceland
Convergent Boundary- is when the plates come together. Continental plates
collide/crash into each other and form mountains over millions of years. Example:
Himalayan Mountains. A special type of convergent boundary = Subduction where
oceanic crust meets continental crust and forms deep-ocean trenches.
Transform- is when the plates slip past each other. Continental plates scrape past each
other, often causing earthquakes. Example: San Andreas Fault.
These types of geological activity can be found along plate boundaries: mountain forming,
earthquakes, volcanoes
Theory of Plate Tectonics: Earth’s plates are in slow, constant motion, driven by
convection currents in the mantle.
Fault- A break in Earth’s crust along which rocks move.
Rift Valley- is when pieces of Earth’s crust diverge on land and forms a deep valley.
You will need to know the steps in sea-floor spreading in order.
You need to know the Theory of Plate Tectonics.
Remember this is a guide to help you study and not a copy of the test. Take your time and
good luck.