Reading Guide – Continental Drift
•It has taken the continents about ______years since the breakup of ______to move to their present locations.
Theory of Plate Tectonics:
•Claims that Earth’s plates are always in ______
–Plates move
•
•
*
–Theory of plate tectonics explains the ______, ______, and ______of Earth’s plates
•Crust rides on top of the ______
•Plates ride on top of ______which is in motion due to ______
–Convection currents moving the plastic rocks of the ______sideways cause large portions of the crust to move called ______plates
–Convection currents can cause plates to move ______from each other or ______each other.
TWO TYPES OF LITHOSPHERIC PLATES
•______crust: made of rocks that are less ______and ride higher on the mantle than oceanic crust; made of ______.
•______crust: rocks that are more ______and ride lower on the mantle than continental crust; made of ______.
PLATE BOUNDARIES
•Movement of Earth’s plates are responsible for most major ______events and ______.
–Responsible for formation of ______, ______, and ______formation
•Plate ______are where edges of plates ______.
Divergent Boundaries
•Forms when two plates move______from each other
–Most occur on the ______floor & form undersea mountain ranges called ______.
–______wells up where plates pull apart creating new ocean crust in a process called ______.
•Ex. Mid-Atlantic Ridge
–Create under water ______
EVIDENCE of SEAFLOOR SPREADING
•______of molten material
•Magnetic stripes in the ______of the ocean floor
•Older rocks are found farther away from a ______
•When two continental plates pull apart, a ______forms
–Ex. East African Rift
•______occurs where there are breaks in the rock of the crust because rocks slip past each other due to plate movements.
CONVERGENT PLATE BOUNDARIES
•Boundaries that form when two plates ______or ______
______
•Compression forces (______)
–Called ______
•Three Types
–______
–Two ______
–Two ______
OCEANIC & CONTINENTAL
•The ______oceanic plate is forced below the ______dense continental plate.
–Oceanic plate ______as it pushes into the mantle forcing ______up to the surface of the continent.
–Forms a ______-______& a long chain of continental ______mountains.
–The movement of one plate under another is called ______
HOT SPOT VOLCANOES
•Hot spots called intra-______regions
– These volcanoes are believed to have sources deeper down in the Earth's mantle that remain in a relatively ______location.
–Plates move over the hot spot
–Ex. The Hawaiian Islands
TWO CONTINENTAL PLATES
•First, the ______between the continents is forced below one of the continents
•Then, when the plates ______the continent crusts ______, ______, & rise up forming mountain ranges.
•Ex. Himalaya & Appalachian Mountains
•______occurs when ______forces bend rocks without breaking them.
TWO OCEANIC PLATES
•One plate is forced ______into the mantle forming a deep ocean ______that sinks & ______.
•______push through the ocean floor forming a chain of ______.
•If a volcano becomes large enough, it ______above sea level & makes a volcanic ______.
–Ex. Japanese Islands, Philippines, Aleutian Islands
TRANSFORM PLATE BOUNDARIES
•Two plates slide ______each other without ______or ______the lithosphere.
–Form ______-slip faults
–______forces
•Earthquakes occur most often at ______boundaries.
•______Fault is an example.
–North America & Pacific plates slide past each other in a N – S direction creating earthquakes.
EARTHQUAKES
•______are large cracks in the Earth’s crust where movement occurs.
–At strike-slip faults, rocks on either side of the fault are under ______& can get locked together.
–When too much pressure builds up, the rocks suddenly slide past each other releasing the ______
–The violent shaking of the Earth’s crust is known as an______.
SEISMIC WAVE
•The ______is the place (underground) in Earth’s crust where the pressure was released.
•Seismic (earthquake) waves spread out in all directions from the focus.
•The ______is the spot on Earth’s surface directly above the focus.
•3 kinds of seismic waves
a.
b.
c.
TYPES OF SEISMIC WAVES
–Primary (P)-waves: originate at the focus
•Travel by ______land as they pass (like a slinky)
•Travel ______through solids than liquid
–Secondary (S)-waves: move land ______to ______
•Only travel through solids
–Land/Surface waves: move ______and ______on earth’s surface (like waves on a pond)
•cause the most ______
MEASURING EARTHQUAKES
•The measure of the strength of an earthquake’s waves is called ______
•Magnitude is measured using a ______and a ______Scale.
SEISMOGRAPH
•Seismic waves cause the seismograph’s ______to vibrate. However, the suspended weight with the pen attached moves very little. Therefore, the pen stays in place and records the drum’s vibrations.