Chapter 2 Definitions

Question 1

Transition zone

Answer 1

Area where the upper and lower mantles merge

Question 2

Core-mantle boundary

Answer 2

Also called the Gutenberg discontinuity, lies 1800 miles beneath the surface and marks the bottom of the mantle

Question 3

Lithosphere

Answer 3

Region of the earth’s crust and upper mantle composed of several plates that “float” on the upper mantle

Question 4

Pangaea

Answer 4

One huge land mass that separated into the present-day continents

Question 5

Syncline

Answer 5

Trough like structure formed when rocks bend downward during folding

Question 6

Anticline

Answer 6

Arch like structure formed when rocks buckle upward during folding

Question 7

Volcanic mountain

Answer 7

Formed when molten rock erupts from a hole in the earth’s crust

Question 8

Domed mountain

Answer 8

Appears to form when molten rock is forced beneath an overlying rock area

Question 9

Tectonic earthquake

Answer 9

Results from sudden movements of rock beneath the earth’s surface

Question 10

Tremor

Answer 10

Weak earthquake

Question 11

Aftershock

Answer 11

Smaller earthquake that often follows a large earthquake

Question 12

Seismology

Answer 12

Study of earthquakes

Question 13

Focus

Answer 13

Point at which an earthquake begins

Question 14

Epicenter

Answer 14

Point on the earth’s surface directly above the focus

Question 15

Volcano

Answer 15

Opening in the earth’s surface through which hot gases, ash, and molten rock are ejected from the earth’s interior

Question 16

Magma

Answer 16

Molten rock

Question 17

Ejecta

Answer 17

Any substance emitted by an active volcano

Question 18

Pahoehoe

Answer 18

“Ropy” lava, lava that hardens to form either a smooth surface or a surface that resembles ropes

Question 19

AA

Answer 19

Lava that hardens into rough, jagged rocks with a crumbly texture

Question 20

Pyroclastic flow

Answer 20

Superheated cloud of gas and volcanic ash that travels swiftly down a volcanic slope

Question 21

Caldera

Answer 21

Huge bowl-shaped crater formed by the collapse of an emptied magma chamber beneath a volcano

Question 22

Lava tunnel

Answer 22

Horizontal underground tube formed when surface lava hardened while the lava beneath remained molten and continued to flow

Question 23

Igneous intrusion

Answer 23

Mass of volcanic rock beneath the surface

Question 24

Geology

Answer 24

Study of the earth