Plate Tectonics
Alfred Wegener was one of the first people to suggest that all of the ________ were joined together in the past. He called the one large continent _________.
continents; Pangaea
Convergent boundaries form...
mountains, volcanoes, and deep sea trenches
What happens at an oceanic-oceanic collision?
the older/denser crust bends under the other. A deep-sea trench is formed.
Subduction
the process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle again
As a continent moves ___ the poles, its climate gets colder.
toward
The fact that the ____ rocks are located at the mid-ocean ridges is evidence for seafloor spreading.
youngest
Lithospheric Plates
A number of rigid, but moving, pieces of the Earth's surface.
Another piece of evidence that explains sea-floor spreading is _________.
Magnetic stripes.
_____________ is the new crust formed at mid-ocean ridges. The plates move apart at a divergent boundary in the ocean.
Sea floor spreading
_________________ is one of the pieces of evidence to understanding Continental Drift.
The fit of the continents
__________ occurs when one plate sinks beneath another plate.
Subduction
Lithosphere
The outer shell of Earth that extends to a depth of 100 km.
Asthenosphere
The partially melted layer of the mantle that underlies the lithosphere.
Mesosaurus and Lystrosaurus are ____.
ancient reptiles (fossils)
Wegener noticed that mountain ranges on the continents of South America and ____ line up.
Africa
Pangaea means...
All Earth
Scientists believe that differences in ____________ cause hot, plastic-like rock in the asthenosphere to rise toward Earth's surface.
Density
Converging Boundaries
Forms when two (Crustal) Lithospheric plates come together.
Divergent boundaries form...
Mid-ocean ridges and rift valleys
Wegener's support for continental drift theory
similar fossils, similar rocks/mountain shapes, and evidence of climate change (glacier deposits in India)
________________ is responsible for the Continental Drift hypothesis.
Alfred Wegener
What happens at a continental-continental collision?
Because the two crusts are the same density, they squeeze and push the crust up to form mountains.
__________ is the idea that the continents move very slowly, over millions of years, parallel to Earth's surface.
Continental Drift
_________ is the key to explaining Plate Tectonics. It causes the plates to move due to the unequal heating and cooling within the mantle.
Convection Currents
Oceanic-Continental Plate Boundary
Denser ocean crust sinks into the asthenosphere. Also known as a subduction zone. Old ocean crust gets pushed into the asthenosphere, where it is remelted and recycled
Diverging Boundaries
Forms when two (Crustal) Lithospheric plates move apart.
Sliding Boundaries
Forms when two (Crustal) Lithospheric plates slide past each other.
A ________ is any preserved evidence of ancient life.
Fossil
Who is responsible for the sea-floor spreading hypothesis?
Harry Hess
The crust and upper mantle make up Earth's......
Lithosphere
The crust and upper mantle make up the ____________.
Lithosphere
Oceanic-Oceanic Plate Boundary
One of the plates is subducted (sinks) under the other
This name comes from two words meaning "all land".
Pangaea
________ is the supercontinent that Wegener suggested occurred on Earth about 300 million years ago.
Pangaea
_________ explains how plates move and cause major geologic features and events on Earth's surface.
Plate Tectonics
Continental-Continental Plate Boundary
Plates buckle and thicken, pushing the continental crust upward creating mountains
What is a boundary between two plates that are moving apart in the ocean called?
Ridge or Mid-Ocean Ridge
Seafloor Spreading
States that youngest rocks of the ocean floor are at diverging boundaries, moving outward.
Continental Drift
The theory that all continents are fragments of Pangaea now drifting apart.
Plate Tectonics
Theory of the formation and movement of the plates that cover the Earth's surface.
Deep-Ocean Trench
a canyon on the ocean floor at which the crust bends downward
Mid-Ocean Ridge
a chain of underwater mountains along which seafloor spreading occurs
Rift Valley
a deep valley on land that forms at a divergent boundary
As a continent moves toward the ____, its climate gets warmer.
equator
Transform boundaries form...
major earthquakes
Until clues on the ___________ led to the idea of seafloor spreading, the mechanism of the continents moving, scientists would not believe Wegener's theory of continental drift.
ocean floor
The continents fit together like ______________.
puzzle pieces
Most of Wegener's scientist friends ____ his hypothesis.
rejected
Harry Hess' theory of __________ explained how ocean crust is generated and destroyed.
seafloor spreading
What happens at an oceanic-continental collision?
the more dense oceanic crust sinks beneath the continental plate, forming a subduction zone.
