Test 2, Chapter 2 Flashcards Preview

8th Science - Earth and Space > Test 2, Chapter 2 > Flashcards

Flashcards in Test 2, Chapter 2 Deck (52):
1

The most abundant element in the earth's crust is ____

oxygen

2

In what type of fault do rocks along one side of the fault move horizontally along the fault?

strike-slip fault

3

Eighty-five percent of all earthquacks are _____ earthquakes

shallow-focus

4

A bowl-shaped hollow more than 2 miles wide, formed by the collapse of an underground magma chamber, is a

caldera

5

The point deep in the earth at which an earthquake begins is the

focus

6

What are large almond-or teardrop-shaped pieces of ejecta formed when lava solidifies

volcanic bomb

7

The narrow zone of active volcanoes that nearly encircles the Pacific basin is the

Ring of Fire

8

About 80% of the world's earthquakes occur in

the circum-Pacific belt

9

The bending or buckling of rocks under great force produces a(n)

fold

10

The inner core of the earth is thought to be

solid

11

An inactive volcano that can erupt again is

dormant

12

The middle of the earth's three layers is the

mantle

13

An instrument used to record the vibrations caused by earthquakes is a(n)

seismograph

14

A large, well known strike-slip fault in western California is the

San Andreas Fault

15

The study of the earth is

geology

16

The study of earthquakes is

seismology

17

All the present-day continents are thought to have been one land mass called

Pangaea

18

An earthquake caused by sudden movements of rock beneath the earth's surface is a(n)

tectonic earthquake

19

A domelike igneous intrusion formed when magma bulges overlying rocks upward is a(n)

laccolith

20

type of volcano consisting primarily of erupted volcanic ash and rock fragments held loosely together

cinder-cone volcano

21

broad, gently sloping volcano made of large quantities of highly fluid lava that hardened into rock

shield volcano

22

volcano formed partly by explosive eruptions of ash and rock fragments and partly by mild lava flows

composite volcano

23

The ______ theory states that rocks spring back to a position of little or no strain at the moment of an earthquake, causing vibrations in the earth's crust

elastic rebound

24

The fastest type of earthquake waves are _____

P waves

25

Small earthquakes that often follow a larger earthquake at frequent intervals for days or even months are called _____

aftershocks

26

The most famous scale of earthquake strength, which rates earthquakes on a scale of 1-9, is the _______

Mercalli scale

27

Deposits of sand and mineral fragments, usually laid down by water, are known as _____

sediments

28

The underground ______ is the actual source of a volcanic eruption

magma chamber

29

A ___ is a sheetlike igneous intrusion formed when magma hardens in a vertical crack

dike

30

type of mountain formed when molten rock collects beneath an overlying rock layer, forcing the layer upward into a blisterlike structure

domed mountain

31

type of mountain formed when rocks on one side of a fault are forced upward and the rocks on the other side are forced downward

fault-block mountain

32

type of mountain formed when molten rock erupts from a hole in the earth's crust

volcanic mountain

33

type of mountain formed when two rock layers are pushed together, causing the layers to buckle

folded mountain

34

The point on the earth's surface directly above the point where an earthquake begins is the

epicenter

35

What is an archlike structure formed when rocks are folded upward?

anticline

36

The channel in a volcano through which gases, ash, and molten rock are ejected from the earth's interior is the

vent

37

A superheated, incandescent cloud of gas and volcanic ash that flows swiftly down a volcanic slope is called

pyroclastic flow

38

Lava that hardens into rough, jagged rocks with a crumbly or ''blocky'' texture is __ lava

aa

39

What is a troughlike structure formed when rocks are folded downward

syncline

40

Lava that hardens into a smooth-textured rock with a ''ropy'' appearance is ___ lava

pahoehoe

41

A particle or block of solid volcanic ejecta is a(n)

pyroclast

42

In what type of fault are rocks on one side of a fault shoved on top of the rocks on the other side

thrust fault

43

A volcano that has erupted within recorded history or is currently producing seismic activity is

active

44

The central portion of the earth is the

core

45

Where are the effects of an earthquake most severe

epicenter

46

In what kind of fault do rocks along one side of the fault sink vertically

normal fault

47

What is the boundary line between the crust and the mantle called

Mohorovicic discontinuity (Moho)

48

What is molten rock beneath the surface of the earth called

magma

49

What theory states that the earth's crust and upper mantle consist of huge plates slowly drifting because of convection currents in the mantle?

plate tectonics

50

What is the area between the upper mantle and the lower mantle called

transition zone

51

What is an underground channel that formed when surface lava hardened before the lava underneath it

lava tunnel

52

Compare and contrast fixed-base systems, base-isolated systems, and energy-dissipation devices.

Answers should include the following ideas:

A fixed-base system is a type of foundation in which the building is attached to bedrock; the energy of an earthquake is absorbed by the building's frame and joints. A downside to this system is that the building may be deformed.

Base-isolated systems are the most common new construction for earthquake resistance. In a base-isolated system, the building is on stiltlike isolators, which separate the building from the foundation and absorb seismic energy.

Energy-dissipation devices are added to structures to absorb seismic energy, lessening the stress on the building and thereby minimizing deformation.

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