Epsc 201 Chapters 4-5

Front 1

Identify the FALSE statement

Igneous rocks are typically coarse-grained if they're intrusive.

Igneous rocks form from the freezing of either lava or magma.

Igneous rocks form in great quantity along the mid-ocean ridge.

Igneous rocks are termed phaneritic if they're fine-grained.

Igneous rocks were the first rocks to exist on Earth.

Back 1

Igneous rocks are termed phaneritic if they're fine-grained.

Front 2

A rock has a medium-gray, fine-grained groundmass with large crystals of plagioclase. Which of the following statements about it is FALSE?

Back 2

The lava flow that produced it got quenched in ocean water.

Front 3

Granite...

Back 3

- Is felsic in composition

- Is the coarse-grained equivalent of rhyolite

- Is a phaenritic rock

- Logically could be found in a batholith

Front 4

After an explosive volcanic eruption on an island, the surrounding sea is full of light-gray floating rock. What must it be?

Back 4

Pumice

Front 5

Which of the following volcanic features is NOT related to plate-boundary magmatism?

Back 5

Kilauea, Hawaii

Front 6

Intrusive igneous rocks

Back 6

Cool slowly and are coarse-grained

Front 7

Bowen's reaction series

Back 7

Allows a geologist to predict what minerals will be grouped in igneous rocks.

Front 8

A black, fine-grained tabular intrusion between two layers of horizontal sedimentary rock must logically be a

Back 8

Basaltic sill

Front 9

Identify the FALSE statement: Felsic magma

- Is associated with explosive volcanic eruptions.

- Is likely to form light-tan, pink, or maroon-colored rocks.

- Is less viscous than mafic magma.

- Is the coolest of magmas.

- Has about 70% silica and little magnesium and iron.

Back 9

Is less viscous than mafic magma.

Felsic is more viscous because the silicon tetrahedrons link up.

Front 10

Identify the FALSE statement: Mafic minerals

- Freeze at a higher temperature than silicic minerals do.

- Are those rich in iron and magnesium.

- Would be at the top of Bowen's reaction series, crystallizing first out of the melt.

- Form rhyolite and granite.

- Form black or dark-gray rocks.

Back 10

Form rhyolite and granite

Front 11

Factors that influence the chemical composition of magmas may include

Back 11

- Mixing of magmas brought together from different locations

- Only partial melting of the source rock

- Melting and assimilation of some of the rock of the magma chamber walls

- The chemical composition of the source rock

Front 12

Identify the FALSE statement: Hot solid rock in the Earth

- May melt if volatiles such as water and carbon dioxide are added.

- May be even hotter than surface lava because of the pressure of overlying rock.

- May experience decompression melting as it rises to shallow depths.

- May melt if heat is transferred to it from hot mantle rock rising up into the crust.

- Maintains uniform composition as it melts and becomes magma.

Back 12

Maintains uniform composition as it melts and becomes magma.

Front 13

Which of the following is NOT an intrusive igneous structure?

Back 13

Pillow lava

Front 14

T/F: According to the plume hypothesis, the plume of a hot spot consists of molten magma rising slowly from the core-mantle boundary and spilling out on Earth's surface.

Back 14

False

Front 15

T/F: The deeper an igneous intrusion, the slower it cools.

Back 15

True

Front 16

T/F: Igneous rocks formed of igneous debris blown out of a volcano are called pegmatites.

Back 16

False

Front 17

T/F: Yellowstone National Park marks the end of a continental hot-spot track.

Back 17

True

Front 18

T/F: Tuff and breccia are both fragmental igneous rocks.

Back 18

True

Front 19

Pillow lavas are evidence of what volcanic circumstance?

Back 19

A submarine volcano

Front 20

A lahar is

Back 20

A volcanic mud-and-debris flow that resembles fluid concrete.

Front 21

The enlarged volcanic craters at Yellowstone National Park, Crater Lake, and Krakatau are

Back 21

Formed by both outward explosion outward and downward collapse.

Front 22

Volcanic mud-and-debris flows, composed of ash, debris, and water

Back 22

Have often resulted in damage and death to humans and their property.

Front 23

Lava of low viscosity

Back 23

- Is logically basalt

- Indicates an area that has little potential for explosive eruptions

- Builds a shield volcanic edifice

- Has low silica content

Front 24

Lava is

Back 24

Molten rock that cools and hardens on Earth's surface.

Front 25

Rhyolite lava

Back 25

- May form a lava dome above the vent

- May freeze in the vent and emerge as a spine

- Has more silica than basalt lava does

- Indicates the tendency for explosive activity

Front 26

Carbon dioxide

Back 26

- Was released at Lake Nyos, Cameroon, Africa, and killed many people.

- Is a common volcanic product that can suffocate animals.

- Is released by magma as it rises and the pressure gets lower.

- Is denser than air.

Front 27

Mt. St. Helens erupted in 1980, sending out gas and pyroclastics. Geologists have found evidence of many eruptions of St. Helens, dating back 37,000 years. The mountain is huge and is composed of layers of lava and pyroclastics. Which of the following is most likely true?

Back 27

It's a stratovolcano (or composite cone).

Front 28

This stratovolcano recently erupted in the United States. Although it warned of its impending eruption, it still killed people, partly because it first blew sideways and produced a monstrous landslide. The explosion sent tons of ash skyward and blasted more than 1,000 feet off the mountaintop. The volcano is:

Back 28

Mt. St. Helens

Front 29

In the 1990s, a Californian was camping in a volcanic area. He died after ignoring posted warnings and sleeping among a stand of dead trees. He was not scalded, not poisoned, not visibly injured, and the campground did not smell bad. What volcanic gas probably killed the camper and the trees?

Back 29

Carbon dioxide

Front 30

Identify the FALSE statement: Plate tectonics theory explains why volcanic activity occurs where it does; for example

Back 30

The volcanoes of Iceland and Surtsey owe their existence to the mantle plume underlying the convergent-plate boundary on which they sit.

(the boundary is divergent)

Front 31

What is the term for an unconsolidated accumulation of any size of pyroclastic grains?

Back 31

Tephra

Front 32

Which of the following events is a warning sign of imminent eruption?

Back 32

- Bulges on the volcano's surface

- Increase in gas emissions and hydrothermal activities

- Earthquake activity

- Change in heat flow from the the volcano's surface

Front 33

Which of the following volcanic phenomena can be triggered by a volcanic eruption under ice?

Back 33

Jokulhaup

Front 34

T/F: Individual volcanoes erupt fairly regularly, and if the recurrence interval is known, their eruptions can be accurately predicted.

Back 34

False

Front 35

T/F: The eruption of rhyolitic lava often creates a steep feature called a lava dome.

Back 35

True

Front 36

T/F: Devil's Tower, Wyoming, and Black Tusk, BC, are landforms that exist because softer volcano exteriors erode faster than solidified lava in fissures and vents.

Back 36

True

Front 37

T/F: Pyroclastic flows almost always bring instant death to any life caught in them.

Back 37

True

Front 38

T/F: Short-term prediction of earthquakes is usually possible; short-term prediction of imminent volcanic eruption has had no proven success

Back 38

False

Front 39

T/F: Volcanic ash and sulfur-rich aerosols can absorb solar radiation and result in cooler average temperatures worldwide.

Back 39

True

Front 40

T/F: The dark areas of the Moon's surface, called mare, are flood basalts that cover 17% of the lunar surface and which formed over 3 billion years ago.

Back 40

True