Extra Credit Questions for EXAM 3

Devils Tower is an example of:

Volcanic Neck

As the silica content of a magma increases, the viscosity of the magma:

Increases

Of the following, the magma with the highest viscosity would have:

a high silica content and low temperature.

Cinder cones typically erupt deadly pyroclastic flows.

False

The term viscosity refers to:

a liquid's resistance to flow

All of the following are likely environmental effects of a volcanic explosion except:

an increased growing season.

Kilauea is an example of a:

Shield Volcano

As the silica content of a magma decreases, the viscosity of the magma:

decreases

Ash and lapilli are the same sized pyroclastic particles.

False

Which of the following characteristics would you NOT expect from an effusive eruption?

Large volumes of pyroclastic materials produced.

Volcanoes are beneficial to humanity in many ways. All of the following are benefits EXCEPT:

some gases released by volcanoes are toxic to humans.

The force that causes pyroclastic volcanoes to explode violently is:

pressure from volcanic gases

Which of the following statements regarding volcanoes is NOT true?

Magma of gentle volcanoes has a higher silica content and a higher viscosity than magma of violent volcanoes.

The force that causes an eruption to occur is mainly due to:

Dissolved gasses in the magma expanding as they approach the surface

All of the following are examples of flood basalts EXCEPT:

Mount Kenya

If a volcano has not erupted in the past few thousand years, but is likely to erupt sometime in the future, it is considered to be:

dormant

A nuee ardente can best be described as a:

flow of hot pyroclastic material.

A volcanic dome forms when:

rising magma cools and hardens within a volcano's crater.

An active volcano is any volcano that:

is currently erupting or has erupted recently (in geological terms)

Cinder cones typically erupt deadly pyroclastic flows.

False

Factors that control the viscosity of a magma are:

All of the above,

Temperature of the magma

Composition of the magma

Amount of dissolved gasses in the magma

These two gasses are the most abundant gasses erupted during an eruption:

Water vapor and carbon dioxide

All of the following are caldera forming volcanoes EXCEPT:

Mount Hood

During volcanic eruptions, these are the two main gasses emitted?

Water vapor and carbon dioxide

Crate Lake in the Pacific Northwest is an excellent example of:

Calderas

The geothermal gradient describes how:

temperature increases with depth within the Earth.

This texture would be unlikely in extrusive igneous rocks?

Phaneritic

The two properties used most to classify igneous rocks are:

Texture and Mineral Composition

A dike is a:

discordant tabular pluton

Bowens Reaction series predicts all of the following except:

Crystal size in the igneous rocks

This texture indicates a period of short, relatively fast cooling and crystallization?

Aphanitic

This igneous rock is well known for its glassy texture:

Obsidian

Volcanic igneous rocks are often referred to as fine-grained because:

The cooling rate is too fast for large crystals to grow

All of the following statements concerning magma movement are true EXCEPT:

a very viscous magma tends to be less explosive.

This igneous rock is well known for its vesicular texture:

Pumice

All of these affect magma generation except?

Crystal size

The main reason that crystals in an igneous rock stop growing is:

They run out of space to grow

As the rate of cooling decreases, particle size in an igneous rock:

increases

If a magma or lava cools relatively fast, the resulting rock will have?

very small crystals

Plutonic rocks are characterized by which type of texture?

Phaneritic

The main difference in the definition of magma and lava is that:

Magma has the gas still dissolved in solution

This is the major volatile in both magmas and volcanic gasses?

Water

Which of the following statements about the creation of magma is true?

Increasing pressure raises the melting point except in the presence of water.

The term texture refers to:

The size and shape of the mineral components

What is the process by which a single parent magma can produce a variety of rocks of different composition?

Fractional Crystallization

Magma rises towards the surface because:

It is less dense than the material around it.

Under which of the following conditions would rocks melt at a lower temperature?

High water content, low pressure

If a magma or lava cools relatively slowly, the resulting rock will have:

Very large crystals

The geothermal gradient describes how:

Temp increases with depth within the Earth

The temperature at which a mineral melts:

is the same temperature at which it crystallizes

The classification of intrusive igneous structures depends on all of the following EXCEPT:

composition and texture

What is the last mineral to form according to Bowen's reaction series?

Quartz

This texture indicated a period of short, relatively fast cooling and crystallization?

Aphanitic

If a lava cools too fast for all the gas to escape, the resulting texture would be considered:

Vesicular

This type of igneous texture occurs when a magma partially crystallizes below the surface:

Porphyritic

A sill is a :

concordant tabular pluton

Plutonic igneous rocks are often referred to as coarse-grained because:

The slow cooling at depth allows large crystals to grow

Which of the following statements concerning batholiths is NOT true?

They commonly consist of the mafic intrusive rock gabbro.

Weathering is best defined as?

The disintegration and decomposition of rocks and minerals at the surface

Frost wedging would be most prominent in:

mid-latitude regions where temperatures hover around 0°C (32°F) during certain seasons.

All soils must have:

A mixture of regolith, organic matter, air, and water

In general, chemical weathering would occur most rapidly in a:

warm, moist climate.

The tendency for material to separate with liquids rising and solid sediment sinking due to shaking is?

Liquefaction

The main difference between regolith and soil is:

soil is the upper few meters of regolith, containing both minerals and organic matter.

These soil layers are the defining layers of a solum (true soil):

O, A, E, and B

Differential Weathering is caused by:

Variations in composition of rocks

The transport of loose sediments by some transport agent such as wind, water, or ice is known as:

Erosion

What is the primary difference between weathering and erosion?

Weathering is the breaking down of rocks; erosion is the transporting of rock fragments.

Rocks and minerals are most stable when they:

are in the environment in which they formed

What is the process involving the removal of loose Earth materials by wind?

deflation

These are the correct order of soil horizons from the surface to the bedrock?

O, A, E, B and C

Which of the following objects have soil on their surface:

The Earth

The primary cause of mechanical exfoliation is:

the removal by erosion of overlying rock and soil.

Joints are important in weathering processes because:

(They increase the exposed surface area of a rock

They provide a pathway into the rock for water

They provide openings for plant roots to enter the rocks)

All of the answers are correct

This slow mass wasting process happens in areas of permafrost:

Solifluction

Which of the following statements correctly describes sand grains after they become airborne?

(Grains overcome by gravity strike other grains, setting them in motion.

Particles move forward in curved, parabolic paths.

Grains overcome by gravity may nudge forward other grains they strike.)

All of the above.

Mechanical weathering can:

change the size and shape of rock structures

The characteristic of loess that makes it an exceptional soil is:

(its angular grains.

its high moisture-holding capacity.

its fresh, unweathered mineral content.)

All of the above.

This term refers to the combination of processes that break rocks into smaller particles.

weathering

Which of the following statements concerning liquefaction is NOT true?

It is caused when a substantial quantity of groundwater is forced into unconsolidated sediment.

Which of the following is an important control of weathering rates:

Rock characteristics

All of the following are important controls of weathering rates EXCEPT:

Amount of nitrogen in soil