Ch 3 - Our Fascinating Earth (3.1 - 3.4) Flashcards

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1
Q

What do we call the study of the earth and its structures?

A

geology

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2
Q

What do we call scientists who study the structure of the earth?

A

geologists

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3
Q

What do we call the outer layer of the earth?

A

the crust

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4
Q

What do we call the boundary between the crust and the mantle?

A

the Moho or Mohorovičić discontinuity

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5
Q

What do we call the innermost region of the earth?

A

core or inner core

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6
Q

What is made up of a mixture of broken-down rocks and decomposed plants and animals

A

soil

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7
Q

By what process is new soil formed?

A

weathering

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8
Q

What type of weathering is caused by ice, flowing water, or windblown sand?

A

physical weathering

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9
Q

What kind of weathering is caused by natural acids slowly eating into a rock and breaking it apart?

A

chemical weathering

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10
Q

What do you call underwater mountain ranges where plates of the earth’s crust are thought to be moving away from each other?

A

mid-oceanic ridges

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11
Q

Name the three main sections of the earth labelled below.

A
  1. crust
  2. mantle
  3. core
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12
Q

Describe the earth’s crust.

A
  • outermost layer of the earth
  • quite thin compared to the size of the earth
  • much is covered by soil, sand, and other sediment
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13
Q

Describe the earth’s mantle.

A
  • 2,900km thick
  • makes up the largest portion of the earth’s interior
  • it is very hot, and temperature increases with depth
  • the rocks are weakened by the heat so that they slowly flow under pressure like warm plastic
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14
Q

Describe the earth’s core.

A
  • innermost region of the earth
  • divided into two sections: inner and outer core
  • made up of metals rather than rock
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15
Q

Which part of the earth’s core is a solid and which part is liquid?

A

The inner core is solid and the outer core is liquid.

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16
Q

What are giant waves caused by earthquakes called?

A

tsunamis

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17
Q

What is the shaking or trembling of the earth’s crust called?

A

an earthquake

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18
Q

What is the study of earthquakes called?

A

seismology

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19
Q

What are scientists who study earthquakes called?

A

seismologists

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20
Q

What do you call the break that appears at the boundary between two moving masses of rock?

A

a fault

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21
Q

What do you call the point under the ground where an earthquake begins?

A

the focus

22
Q

The strength of an earthquakes is called its…

A

magnitude

23
Q

The regions of the earth’s crust where most earthquake faults are found are called…

A

seismic belts

24
Q

In which region do most earthquakes occur?

A

the Circum-Pacific Belt

25
Q

What do you call the place at ground level that is directly above the focus of an earthquake?

A

the epicentre

26
Q

What scale is used to measure the strength of an earthquake?

A

the Richter scale

27
Q

How can the motions of the earth’s plates cause earthquakes?

A

Sometimes the edges of moving plates become stuck and cease to move, allowing huge forces to build up. The force may eventually become so great that the plates suddenly break free and slide against each other for several seconds, producing an earthquake.

28
Q

What do you call melted rock that is still underground?

A

magma

29
Q

What do you call a reservoir of magma a few miles beneath the surface that may give rise to a volcano?

A

a magma chamber

30
Q

What do you call a vent that allows molten rock and hot gases to escape from within the earth?

A

a volcano

31
Q

What do you call an opening in the ground through which a volcano erupts?

A

a vent

32
Q

What is the name given to melted rock that has reached the earth’s surface?

A

lava

33
Q

What name is given to the belt of volcanoes that encircles the Pacific Ocean?

A

the Ring of Fire

34
Q

What do you call holes or cracks serving as escape vents for underground gases?

A

fumaroles

35
Q

Lava fragments that solidify into rock fragments almost immediately are called…

A

tephra

36
Q

What are three different types of tephra?

A

volcanic ash
lapilli
volcanic bombs

37
Q

What is volcanic ash?

A

the smallest fragments of tephra, resembling dust or fine sand

38
Q

What is lapilli?

A

fragments of tephra that are smaller than bombs or blocks but larger than volcanic ash; means little stones

39
Q

What are volcanic bombs?

A

Volcanic bombs are fragments of tephra that are more than 2.5 inches across. Some may be several feet across!

40
Q

What is the depression at the top of a volcano called?

A

a crater

41
Q

What is a caldera?

A

a huge bowl-shaped depression formed when an empty magma chamber collapses after a volcanic eruption

42
Q

What is an active volcano?

A

An active volcano is one that has erupted recently or is considered likely to erupt in the near future

43
Q

What is a dormant volcano?

A

A dormant volcano is one that erupted many years ago and is now inactive but may erupt again in the future

44
Q

What is an extinct volcano?

A

An extinct volcano is one that has not erupted in recorded history or is unlikely to ever erupt again

45
Q

What type of volcano (below) is dome-shaped and formed by eruptions of fluid, runny lava that build up gradually? (The Hawaiian Islands were formed by this type of volcano.)

A

shield volcano

46
Q

What type of volcano (below) is relatively small, cone-shaped, formed mostly of tephra, and quickly eroded? (Paricutín is an example.)

A

cinder cone volcano

47
Q

What type of volcano (below) is steep-sided and formed by alternating layers of fluid lava and tephra? (Mt. St. Helens is an example.)

A

composite volcano

48
Q

Describe a Hawaiian eruption.

A

The volcano produces a high amount of fluid lava that surges from the vent like water from a fountain. If it gushes from a narrow vent it may shoot in the air, and if it erupts from a long crack it may form a sheet-like fountain called a fire curtain. It can also pool within the vent to form a ‘lake’ of lava.

49
Q

Describe a Strombolian eruption.

A

Strombolian eruptions are noisy but mild, with globs of hot lava flung into the air where they harden into volcanic bombs.

50
Q

Describe a Plinian eruption.

A

Hot clouds of gas and dust are expelled high into the air, usually quite violently. The ash clouds that form can travel completely around the world.

51
Q

What do we call the huge pieces of the earth’s crust that “float” like rafts on the upper mantle?

A

plates