12.1

Question 1

continental drift theory

Answer 1

that the continents have not always
been in their present locations but have “drifted” there over millions of
years

Question 2

Paleoglaciation

Answer 2

both to the extent of ancient glaciers

and to the rock markings they have left behind.

Question 3

tectonic plates

Answer 3

Earth is broken into large, movable slabs of rock

Question 4

Volcanoes

Answer 4

openings in Earth’s surface, that, when

active, spew out gases, chunks of rock, and melted rock.

Question 5

earthquake

Answer 5

a sudden, ground-shaking release of

built-up energy at or under Earth’s surface.

Question 6

Paleomagnetism

Answer 6

the study of the magnetic properties of ancient rocks

Question 7

magma—

Answer 7

molten rock

from beneath Earth’s surface

Question 8

c hot spot

Answer 8

an area where molten rock rises to Earth’s

surface

Question 9

magnetic reversal

Answer 9

It not only changes in strength from time to time but, over thousands of years, its direction can completely reverse