Plate Tectonics

Question 1

Alfred Wegener

Answer 1

German meteorologist and geophysicist was first to advance idea of mobile continents in 1912

Question 2

Continental drift

Answer 2

Continents are slowly drifting across globe

Question 3

Paleomagnetism

Answer 3

The study of earths ancient magnetic field

Question 4

Magnetic dip/inclination

Answer 4

The degree to which a magnetic particle points into earths surface.

Question 5

Mid-ocean ridge

Answer 5

A continuous underwater mountain range that winds through every ocean basin in the world

Question 6

Sea floor spreading

Answer 6

New ocean floor is split in two and carried away from the axis, replaced by upwelling of volcanic material that fills the void with new strips of seafloor

Question 7

Spreading center

Answer 7

The axis of the mid-ocean ridge

Question 8

Ocean trenches

Answer 8

Deepest parts of ocean floor and resemble a narrow crease

Question 9

Subduction

Answer 9

Lithospheric plate that bends downward and slowly plunges back into earths interior

Question 10

Subduction zone

Answer 10

Sloping area from the trench along the downward plate

Question 11

Heat flow

Answer 11

Heat from earths interior released to the surface

Question 12

Earthquakes

Answer 12

Sudden releases of energy caused by fault movement or volcanic eruptions

Question 13

Asthenosphere

Answer 13

Entirely contained within upper mantle

It is a relatively hot plastic (can mold) region below lithosphere so it will flow when gradual force is applied to it

Question 14

Mesosphere

Answer 14

Beneath asthenosphere

More rigid due to increased pressure at depth

Question 15

Lithosphere

Answer 15

Relatively cool, rigid shell that includes all of the crust and the topmost part of the mantle
It is brittle

Question 16

Oceanic crust

Answer 16

Composed of igneous rock, basalt, which is dark colored and has high density of 3.0g/cm^3

Question 17

Continental crust

Answer 17

Composed of lower density and lighter-colored igneous rock, granite. Has density of around 2.7g/cm^3

Question 18

Isostatic adjustment

Answer 18

The vertical movement of crust-is the result of buoyancy of earths lithosphere as it floats on the denser, plastic-like asthenosphere below.

Question 19

Divergent boundaries

Answer 19

Occurs where two plates move apart such as along crest of mid-ocean ridge where sea floor spreading creates new oceanic lithosphere
New seafloor created
Ocean to ocean or continent to continent

Question 20

Oceanic rises

Answer 20

The gently sloping and fast spreading parts of the mid ocean ridge

Question 21

Oceanic ridges

Answer 21

Steeper sloping and lower spreading areas of mid-ocean ridge

Question 22

Convergent boundaries

Answer 22

Where two plates move together and collide-results in destruction of ocean crust as one plate plunged below the other and is ee melted in mantle
Forms deep ocean trenches

Question 23

Oceanic-continental convergence

Answer 23

Denser ocean plate subducts
Basaltic rock melted and begins to rise to surface through the overriding continental plate.
Basalt rich magma mixes with granite of continental crust and make andesitic volcanic eruptions

Question 24

Oceanic-oceanic convergence

Answer 24

Denser ocean plate is subducted (usually older because more time to cool) so molten material is mostly granitic and makes volcanoes but basalt has less silica so less viscous so eruptions not as destructive.
Makes deepest ocean trenches

Question 25

Continental-continental convergence

Answer 25

Tall uplifted mountain range created by collision of two plates

Question 26

Transform faulting

Answer 26

Movement of one plate past another produces shallow but strong earthquakes in lithosphere.
Always occurs between two segments of mid ocean ridge
Oceanic transform fault and continental transform fault

Question 27

Mantle plumes

Answer 27

Columnar areas of hot molten rock that arise from deep within mantle

Question 28

Hotspots

Answer 28

Areas where mantle plumes come to surface

Question 29

Theory of Plate Tectonics

Answer 29

The outermost portion of earth is composed of a patchwork of thin, rigid plates that movie horizontally with respect to one another