Chapter 2

Question 1

Lithosphere

Answer 1

Earths crust and uppermost part of the layer below (mantle) form the lithosphere
Extends to 100-150 km

Question 2

Lithosphere plates

Answer 2

The lithosphere is not a single shell , but consists of several large pieces also know just as plates
There are 12 major plates and several minor plates

Question 3

Continental lithosphere

Answer 3

Is thicker than oceanic lithosphere

Question 4

Asthenosphere

Answer 4

What the plates rest on
A zone in the upper mantle (jelly-like solid)
Allows plates to move

Question 5

Divergent boundaries

Answer 5

(Ocean ridges)
New lithosphere is created from molten material rising from asthenosphere
Plates move away at the axis of Submarine mountain ranges called mid-ocean ridges

Question 6

Convergent boundaries

Answer 6

(Subduction zones or areas of continent-continent-collision)
Old lithosphere is destroyed
one plate sinks into the mantle below the other in subduction zones
creates trenches (places between the two plates)

Question 7

Transform faults

Answer 7

(Neutral plate boundaries)
Lithosphere is neither created nor destroyed
slide past one another along vertical zone of fracturing called a transform fault
Most break ocean ridges into segments

Question 8

Plate boundary

Answer 8

Place where two plates make contact

Question 9

Triple junction

Answer 9

Where three plates come together

Question 10

Sea floor spreading

Answer 10

Ocean becomes wider through this process where new lithosphere moves outward from the axis to the flanks of the ridge

Question 11

Theory of plate tectonics

Answer 11

Plate tectonics explains the outer layer of the earth as a group of separate plates that move with respect to each other and change the Earth’s surface as they move

Question 12

volcanic islands

Answer 12

on convergent plate boundaries where the overriding plate is made of oceanic lithosphere

Question 13

continental arc

Answer 13

on convergent plate boundary like the Andes Mountains where the overriding plate is made of continental lithosphere

Question 14

continental collision

Answer 14

when subduction completely consumes an oceanic plate between two continents and forms a collisional mountain belt

Question 15

Continental rifts

Answer 15

places where continental lithosphere is stretched and pulled apart in the process of breaking apart at a new divergent margin. if successful, a continent splits into two pieces separated by a new oceanic plate, which gradually widens by seafloor spreading.

Question 16

tectonic cycle

Answer 16

new oceanic lithosphere is created at the ocean ridges, moves away from the ridges during seafloor spreading, and returns to the mantle in subduction zones.

Question 17

Principle of uniformitarianism

Answer 17

ancient salt deposits, reefs, and glacial deposits should have formed in locations similar to those where they form today

Question 18

Ring of Fire

Answer 18

surrounding the Pacific Ocean

Most volcanoes are concentrated in narrow belts near the edges of continents

Question 19

paleomagnetism

Answer 19

some rocks that contain magnetite or hematite therefor preserve a weak record of Earth’s ancient magnetic field

Question 20

reverse polarity

Answer 20

a compass needle that points to today’s north magnetic pole would swing around and point south

Question 21

hotspots

Answer 21

an area of unusual volcanic activity not associated with processes at plate boundaries.

Question 22

mantle plume

Answer 22

a column of very hot rock that rises by slow plastic flow from deep in the mantle.

Question 23

seamounts

Answer 23

when old volcanoes sink below the ocean surface

Question 24

active continental margin

Answer 24

where earthquakes and volcanic eruptions are common

Question 25

passive continental margin

Answer 25

where earthquakes and volcanic eruptions are rare.