Unit 2

Question 1

the recognition that the lithosphere is divided into mobile rigid plates move over the asthenosphere

Answer 1

plate tectonic theory

Question 2

this theory relates seemingly unrelated phenomena, showing how geologic features and events are related

Answer 2

plate tectonic theory

Question 3

because of the moving plates…

Answer 3

Earth’s surface is always changing

Question 4

in 1915 he proposed the idea of continental drift based on an abundance of evidence

Answer 4

Alfred Wegener

Question 5

Wegener’s evidence for the plate tectonic theory:

Answer 5

1. fit of continents
   2.glacial data- he found matching glacial striations
2. distribution of fossils

Question 6

Why did scientists think Wegener was wrong? (What couldn’t he explain?)

Answer 6

1. couldn’t explain how continental crust could move through denser oceanic crust
2. couldn’t explain why the plates would move

Question 7

How were Wegener’s theories proven true

Answer 7

technological advances that allowed observations of the seafloor

Question 8

detailed mapping for depth variations

Answer 8

bathymetry

Question 9

new crust moves away from mid-ocean ridges

Answer 9

sea-floor spreading

Question 10

he discovered that magma rises up at mid-oceanic, forming basaltic oceanic crust

Answer 10

Harry Hess

Question 11

what is the place where old crust sinks back down into the mantle

Answer 11

deep-ocean trenches

Question 12

rocks recording the position of magnetic north

Answer 12

paleomagnetism

Question 13

why does paleomagnetism happen?

Answer 13

an Fe-rich mineral will crystallize to align with magnetic north

Question 14

True or false: Magnetic north changes over geologic time.

Answer 14

true

Question 15

describes that if a continent is in a fixed position, the magnetic pole must move- likewise if the pole is fixed, the continent must be drifting

Answer 15

polar-wander paths

Question 16

what records magnetic anomalies?

Answer 16

Fe-rich minerals making up the oceanic crust

Question 17

what drives plate movement?

Answer 17

mantle convection, ridge-push, slab-pull

Question 18

-density-driven
-can’t explain geometry seen at plate boundaries and differing plate motion velocities
-not the only thing causing plates move

Answer 18

mantle convection

Question 19

-lithosphere at mid-ocean ridges lies at a higher elevation
-gravity causes the elevated lithosphere at the ridge-axis to push lithosphere away from the ridge

Answer 19

ridge-push

Question 20

-downgoing plates are more dense than the asthenosphere
-willingly sinks, pulling the rest of the plate

Answer 20

slab-pull