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Terms in this set (61)
What is Wagner's hypothesis called today?
What was the single land mass that all the continents formed?
What did Wagner think happened over the millions of years?
All the continents drifted into their present day positions
Where were the fossils from the extinct reptile Mesosaurus found?
South America and Western Africa
Give an example of a mountain chain that seems to continue from one continent to others across the ocean.
What do layers of ancient glacier debris in Southern Africa and South America indicate?
That Africa and South America were once together
Why wasn't Wagner's hypothesis proved in his lifetime?
Undersea mountain ranges with steep, narrow valleys in the center
sea-floor sediment closer to a ridge is?
rocks closer to a ridge are?
A crack in Earth's crust
The study of the magnetic properties of rocks
The mechanism that causes continents to move
Process of Sea-floor Spreading
New oceanic Lithosphere (sea floor) forms as magma rises to surface and turns solid at a mid-ocean ridge
Dense crust made of rock that is rich in iron and magnesium
blocks of Earth's shell that ride on a layer of the mantle
solid, plastic layer of the mantle beneath the Lithosphere
Low density crust made of rock and rich in silica
The solid outer layer of Earth, that consist of the crust and the rigid upper part of the mantle
What is "Plastic" rock? How does it move?
A solid rock that is under great pressure and it flows very slowly like putty
How many major tectonic plates is there?
Why are boundaries of tectonic plates not always easy to identify?
Some boundaries aren't along a coastline
A sudden movement along a boundary of a tectonic plate
What does frequent earthquakes in an area indicate?
Two or more plates meet in that area
How do volcanoes help locate plate boundaries?
Volcanoes form when plate motions generate magma that erupts on the surface
A zone of active volcanoes that encircles the Pacific Ocean?
"Ring of Fire"
boundary between tectonic plates that are moving away from each other
boundary between two tectonic plats that are sliding past each other horizontally
A zone where one plate moves under another
boundary between tectonic plates that are colliding
undersea mountain range
short segements of a mid-ocean that are connected by transform boundary
narrow area forms where plates at a Divergent boundary seperate
Where are Divergent boundaries located?
What is another word for sinks?
Oceanic plate subducts, it releases fluids into the mantle, causing magma to form and rise to the surface
neither plate subducts neither plate is more dense, the colliding edges crumple and an uplift forms large mountains ranges
example of a large mountain range
The Himalaya Mountains
one plate subducts and a deep ocean trench forms, fluids from subducted plate causes mantle rock to melt and form magma, magma rises, forms island arc
example of a feature that formed when two plates made of oceanic Lithosphere collided?
What causes earthquakes to form at transform boundaries?
plates scraping past each other in little spurts
How do transform boundaries differ from others?
No magma is involved
example of a transform boundary?
San Andres Fault
force exerted by a sinking plate caused by the subduction of the lithosphere into the asthenosphere
two ways continents can change?
Size and shape
rocks and fossils of a terrane?
The rocks and fossils from one terrane differs from all the surrounding terranes
what is found at the boundaries of Terranes?
Forms Terranes take when becoming part of a continent
1) mountain or 2) part of the surface area
three kinds of material that can form terranes
1) large chunks of continental crust 2)Seamounts 3)Atolls
Example of a mountain chain that formed when a large terrane and a continent collided?
Effects of populations of organisms when continents rift or form or as mountains form
populations of organisms get separated
Unique species that evolved in Madagascar
large landmasses formed from smaller continents
What causes a supercontinent to break apart?
heat inside Earth causes rifts in the supercontinent
Name of supercontinent that formed 300 million years ago?
Mountain that formed when Pangaea was created?
plastic solid layer below lithosphere
continents break apart
hotter materials rise to surface magma comes up
when continents break apart and then form one big continent over millions of years