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Geology 111 > Chapter 4 > Flashcards

Chapter 4 Flashcards

1
Q

What is Volcanism

A

When magma makes it way to the earth’s surface.

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2
Q

Vocanoes

A

landforms formed by the extrusion of lava or the ejection of rock fragments from a vent.

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3
Q

Explosive Eruptions

A

Also called pyroclastic eruptions long story short they erupt violently.

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4
Q

Effusive Eruptions

A

Eruptions dominated by lava flows.

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5
Q

How was the atmosphere created

A

By degassing magma during the time following Earths formation.

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6
Q

What is VEI an acronym for?

A

Volcanic Explosivity Index

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7
Q

viscosity

A

Does it flow like corn syrup? If yes then it has a high viscosity.

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8
Q

what are the three factors in lavas viscosity?

A
  1. The amount of silica it contains. 2. The temperature. 3. The amount of gas dissolved in magma.
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9
Q

How silica rich are Felsic rocks?

A

High usually 65% or more. Examples include rhyolite.

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10
Q

How silica rich are Mafic Rocks?

A

Low usually about 50% Basalt is a common Mafic Rock.

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11
Q

How silica rich are Intermediate rocks?

A

usually between felsic and mafic rocks 50%-65% silica.

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12
Q

Vent

A

The opening through which an eruption takes place

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13
Q

Crater

A

A basinlike depression over a vent at the summit of a volcanic cone. Material is not always ejected from the central vent.

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14
Q

What is a flank eruption?

A

Lava pours from a vent on the side of a volcano.

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15
Q

What are Effusive Eruptions classified by?

A

The lava flow.

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16
Q

pahoehoe

A

The skin cools on lava and it looks ropy or billowy surface. Kind of like fat roles think jabba the hutt.

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17
Q

spatter cone

A

a small steep sided cone built from lava sputtering out of a vent.

18
Q

What is a Lava Tube?

A

A tunnel like conduit for lava to flow.

19
Q

Flood basalts

A

A vast outpouring of lava over a large area with multiple lava flows. It kind of looks like a wetland for lava.

20
Q

Columnar Jointing

A

Volcanic rocks in parallel, usually vertical columns, mostly six-sided; also called columnar structure.

21
Q

Pillow structure

A

Pillow structure is formed when lava erupts into water.

22
Q

Pyroclastic Flow

A

A mixture of gas and pyroclastic debris that is so dense that it hugs the ground as it flows rapidly in low areas. Think of a flash flood.

23
Q

what are the 3 different types of volcanoes?

A
  1. Shield 2. Cinder Cone 3. composite.
24
Q

How are Shield Volcanoes constructed?

A

Broad, gently sloping cone constructed of solidified lava flows. Think of captain Americas shield.

25
Q

What is a Cinder Cone constructed of?

A

A volcano constructed of pyroclastic fragments ejected from a central vent. commonly have a slope of about 30 degrees. also known as pumice cones.

26
Q

Composite Volcano

A

Constructed of Alternating layers of pyroclast and lava flow.

27
Q

Circum-Pacific belt

A

Major belt around the edge of the pacific ocean on which most composite volcanoes are located and where many earthquakes occur.

28
Q

What are Lava Domes.

A

steep-sided dome-or spine-shaped mass of volcanic rock. Usually formed from highly viscous lava that does not flow very far before it solidifies.

29
Q

What is a Caldera?

A

A volcanic depression much larger tan the original crater having a diameter of at least 1 kilometer. Crater Lake is an example of this.

30
Q

What is midigation

A

Reducing the impact of volcanic eruptions.

31
Q

What likely killed the people in Pompeii

A

Hot pryloclasts.

32
Q

Lahars

A

Really intense flash floods, but like on the river scale.

33
Q

Active volcanoe

A

A volcano that is either currently erupting or has erupted recently.

34
Q

Dormant or extinct volcanoes.

A

Volcanoes that have not erupted in a very long time.

35
Q

What is the earliest notifying feature that a volcano is going to explode?

A

Increased seismic activity.

36
Q

What are the only conditions that mantle rocks melt?

A

Decompression melting and flux melting.

37
Q

convergent boundaries and volcanoes

A

Traditionally the volcanoes are composite in construction and the most known volcanoes are composite.

38
Q

Where do volcanoes that form away from plate boundaries form from?

A

Hot spots or plums from the earth’s core.

39
Q

What are the three most deadly volcanic hazards?

A
  1. Tsunami 2.Pyroclastic Flows 3.Famine and other indirect effects.
40
Q

What are the three components of lava?

A
  1. Crystals 2.Molten silicate rock 3.Gases

Geology 111 (22 decks)

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