Chapter 2 Plate Tectonics: The Unifying Theory Flashcards
Explain continental drift
Driven by earths internal heat engine, hot mantle rises at boundaries where plates separate, forming new lithosphere. The lithosphere cools and becomes more rigid as it moves away from these boundaries, eventaully sinking back into the mantle under the pull of gravity at other boundaries where plates converge. This is called convection and causes the continents to drift
What kind of divergent boundaries do we get?
Oceanic spreading centers and continental rift zones
What type of convergent boundaries do we get?
Ocean-Ocean convergence
Ocean-Continent convergence
Continent-Continent convergence
Name two types of transform fault boundaries
Continental transform fault
Mid ocean ridge transform fault
Explain divergent and convergent boundaries.
Divergent boundaries are places where plates move apart while in convergent boundaries they move closer together in a process called subduction
What happens at oceanic spreading centers?
Tensional forces of mantle convection pull apart two plates marked by a mid-ocean ridge, that exhibits earthquakes, volcanism and rifting
What is plate tectonics?
The theory that the lithosphere is separated into about a dozen rigid plates that move over Earth’s surface and these plates move in relation with each other through divergent, convergent and transform-fault boundaries.
What characterizes continental rifting?
Rift valleys, volcanism and earthquakes distributed over a wider zone than is found at oceanic spreading centers.
Explain Ocean-Ocean convergence
Where Oceanic Lithosphere meets oceanic lithosphere, one plate is subducted beneath the other and a deep sea trench and a volcanic island arc is formed
example the Mariana islands and Mariana’s Trench in the Pacific
Explain Ocean-Continent convergence
When oceanic lithosphere meets continental lithosphere, the oceanic lithosphere is subducted and a volcanic mountain belt is formed at the continental margin.
Example the Andes in South America
Explain Continent-Continent Convergance
Where two continents converge, the crust crumples and thickens, creating high mountains and a wide plateau
Example the Himalayas in India
What methods have geologists developed measure the rates and know the history of plate movements?
Geologists use the sea floor as a magnetic tape recorder,
Deep-sea drilling for oceanic cores to measure and Geodesy which is the ancient science for measuring the shape of Earth and locating points on its surface
What kind of forces drive plate tectonics?
Ridge push and slab pull
Where do the Plate-Driving forces originate?
Some theories state they are caused by the gravitational pull of subducting plates. Another is heat built up over time forming bulges in the mantle beneath the plates which cause the plates to rift apart and convection where hot matter is rising in one place and cold matter sinks in another
How deep does plate recycling occur?
Up to 2890km beneath the crust through whole mantle convection
