Glossary

Question 0

Benioff zone

Answer 0

Inclined zone of earthquake foci that dips beneath an island arc or active continental margin at approx 45 degrees

Question 1

Asthenosphere

Answer 1

Partially molten layer below the lithosphere that has low seismic wave velocities and high seismic attenuation

Question 3

Cone

Answer 3

A steep, cone-shaped hill formed around a volcano vent by the eruption of rock fragments

Question 4

Continental drift

Answer 4

The hypothesis that the continents slowly move across the earth’s surface

Question 5

Convection currents

Answer 5

Circular currents in the mantle caused by the magma being heated by the core of the earth

Question 7

Fault

Answer 7

Surface along which rocks move when they pass their elastic limit and break

Question 8

Crust

Answer 8

The layer of rock that forms the earth’s outer surface

Question 9

Caldera

Answer 9

A large, circular depression in a volcano area formed by eruption or collapse

Question 10

Inner core

Answer 10

A dense sphere of solid iron and nickel at the centre of the earth

Question 12

Mid ocean ridge

Answer 12

A underwater mountain chain where new ocean floor is formed

Question 13

Lithosphere

Answer 13

The solid, outer layer of the earth that consists of the crust and the rigid upper part of the mantle

Question 14

Ocean trench

Answer 14

A deep valley along the ocean floor through which oceanic crust slowly sinks toward the mantle

Question 15

Plate tectonics

Answer 15

The theory that pieces of the earth’s lithosphere are in constant motion, driven by convection currents in the mantle

Question 16

Rift Valley

Answer 16

A deep valley that forms when two plates move apart

Question 18

Mantle

Answer 18

The layer of hot, solid material between the earth’s crust and core

Question 19

Outer core

Answer 19

A layer of molten iron and nickel that surrounds the inner core of the earth

Question 20

Pangea

Answer 20

The large supercontinent that existed 250 million years ago

Question 21

Sea floor spreading

Answer 21

Hess’ theory that new sea floor is formed when magma is forced upward towards the surface at a mid ocean ridge

Question 22

Subduction

Answer 22

A geological process in which one edge of a crustal plate is forced sideways and downward into the mantle below another plate

Question 31

Seismic waves

Answer 31

Vibrations that travel through the earth, carrying the energy released during an earthquake

Question 35

Destructive plate boundary

Answer 35

A zone where two tectonic plates are colliding as they move towards each other

Question 36

Hot spot

Answer 36

A small area of the Earth’s crust where an unusually high heat flow is associated with volcanic activity, most of which are located well away from plate bohndaries