Plate Tectonics

Question 1

Plate tectonics theory

Answer 1

Geo of ocean floor

Question 2

Rift Valley

Answer 2

Ridge that is splitting apart under tension

Question 3

Sea floor spreading

Answer 3

Spreading by convection currents in the mantle

Question 4

Paleomagnetism

Answer 4

“Fossil” magnets that show the orientation of earths magnetic field at the time when crystallized

Question 5

Normal polarity

Answer 5

Periods where the mag. field was oriented with north magnetic pole in north

Question 6

Reversed polarity

Answer 6

Opposite of normal

Question 7

Polarity chrons

Answer 7

The major intervals of alternating polarity

Question 8

Relative velocity

Answer 8

Compares movement of one plate with respect to another

Question 9

Absolute velocity

Answer 9

Compared plate movement to a fixed reference frame

Question 10

Slab-pull

Answer 10

A pull on the plate as the dense oceanic slab descends under its own weight into subduction

Question 11

Ridge-push

Answer 11

Gravity makes the lithosphere slip off the elevated ridge

Question 12

Basal drag

Answer 12

Resistance to flow exerted on the bottom of the plate by the underlying asthenosphere

Question 13

Mantle resistance

Answer 13

Frictional resistance to the movement of the subducting plate through the asthenosphere and mesosphere

Question 14

Friction

Answer 14

Resistance along transform faults and between converging slabs of lithosphere and subduction zone; shear between two plates

Question 15

Continental drift

Answer 15

Wegener

Geologic evidence - rock structure and type
Fossil evidence
Glacial evidence
Paleoclimatic evidence