GEOL 105 FINAL EXAM UD
QUESTIONS AND ANSWERS ALL
CORRECT
Which of the three common magmas - mafic (basaltic), intermediate (andesitic), felsic
(rhyolitic) - has the highest amount of silica and therefore the highest viscosity? -
Answer- felsic
In the following list of magmas, only one is likely to explode - the others will produce
lava flows or spatter to form small cinder cones or ooze out to form lava domes. Which
one of the following magmas is most likely to produce an explosive volcanic eruption
when it reaches the Earth's surface? - Answer- An andesitic magma with gas
A mafic magma at 1200°C intrudes into silica -rich continental crust that has a melting
point of 850°C. What could happen as a result of this? - Answer- The continental crust
will melt and because it is high silica rock it will form a felsic magma.
Both lahars and pyroclastic flows result from a violent eruption. How are they different? -
Answer- Pyroclastic flows are mixtures of hot gas and ash, lahars are mudflows from a
mix of ash and water from melting snow/ice or rain.
A caldera can form when: - Answer- a volcano collapses during a massive Plinian
eruption
Repeated Strombolian style eruptions will build a __________ - Answer- cinder cone
After a watershed is urbanized, flood discharges typically - Answer- increase
Meandering rivers migrate over time across their floodplain and actually create their
floodplains by eroding and depositing sediment over time. - Answer- True
In which "reservoir" of the Earth's hydrological cycle is most of the world's water stored?
- Answer- oceans
The two types of rivers described in class are ? rivers and ? rivers. - Answer- alluvial
and bedrock
According to your textbook, the two types of floods are flash floods and ? floods. -
Answer- downstream
, A ? is a relatively flat lowland that borders a river, usually dry but subject to flooding
every few years. - Answer- floodplain
Delaware is unlikely to experience significant flooding in the future. - Answer- False
The width and depth of a stream, along with the flow velocity are used to calculate: -
Answer- discharge
Which of the following are typically true of bedrock streams? - Answer- Fast-flowing,
steep terrain and narrow valleys.
Why do large downstream floods, like the 1993 Mississippi-Missouri floods, take weeks
to develop? - Answer- Large streams have large drainage basins and can handle a
large discharge before flooding, therefore it takes longer to build up to flood stage.
A drawback of building levees and floodwalls to protect a city is that: - Answer- water
that would flood the city is instead forced downstream, making the flooding there worse.
If you encounter a flooded roadway while driving you should: - Answer- stop and turn
around, do not try driving or even wading across.
The _______________ occurs when the elevation of a stream's surface exceeds that of
the stream bank. - Answer- flood stage
The number of tributaries a stream has is used in determining: - Answer- stream order.
An elevated area along a length of a stream bank is a ? - Answer- levee
Increasing the slope steepness past the _______________ increases the likelihood of a
flow-type mass movement. - Answer- angle of repose
The probability that a landslide will occur on a slope increases when both the driving
forces (gravity and loads) and the resisting forces (friction and cohesion) increase -
Answer- False
Slopes composed of soil that are fully saturated with water are susceptible to landsliding
because: (There are two possible correct answers - please click both.) - Answer- The
pore pressure of the water pushes the mineral grains apart, reducing the friction
between them, lowering the strength of the soil
Water is heavy and increases the load
A mass of material moving in coherent pieces down a defined surface is a ? - Answer-
slide
QUESTIONS AND ANSWERS ALL
CORRECT
Which of the three common magmas - mafic (basaltic), intermediate (andesitic), felsic
(rhyolitic) - has the highest amount of silica and therefore the highest viscosity? -
Answer- felsic
In the following list of magmas, only one is likely to explode - the others will produce
lava flows or spatter to form small cinder cones or ooze out to form lava domes. Which
one of the following magmas is most likely to produce an explosive volcanic eruption
when it reaches the Earth's surface? - Answer- An andesitic magma with gas
A mafic magma at 1200°C intrudes into silica -rich continental crust that has a melting
point of 850°C. What could happen as a result of this? - Answer- The continental crust
will melt and because it is high silica rock it will form a felsic magma.
Both lahars and pyroclastic flows result from a violent eruption. How are they different? -
Answer- Pyroclastic flows are mixtures of hot gas and ash, lahars are mudflows from a
mix of ash and water from melting snow/ice or rain.
A caldera can form when: - Answer- a volcano collapses during a massive Plinian
eruption
Repeated Strombolian style eruptions will build a __________ - Answer- cinder cone
After a watershed is urbanized, flood discharges typically - Answer- increase
Meandering rivers migrate over time across their floodplain and actually create their
floodplains by eroding and depositing sediment over time. - Answer- True
In which "reservoir" of the Earth's hydrological cycle is most of the world's water stored?
- Answer- oceans
The two types of rivers described in class are ? rivers and ? rivers. - Answer- alluvial
and bedrock
According to your textbook, the two types of floods are flash floods and ? floods. -
Answer- downstream
, A ? is a relatively flat lowland that borders a river, usually dry but subject to flooding
every few years. - Answer- floodplain
Delaware is unlikely to experience significant flooding in the future. - Answer- False
The width and depth of a stream, along with the flow velocity are used to calculate: -
Answer- discharge
Which of the following are typically true of bedrock streams? - Answer- Fast-flowing,
steep terrain and narrow valleys.
Why do large downstream floods, like the 1993 Mississippi-Missouri floods, take weeks
to develop? - Answer- Large streams have large drainage basins and can handle a
large discharge before flooding, therefore it takes longer to build up to flood stage.
A drawback of building levees and floodwalls to protect a city is that: - Answer- water
that would flood the city is instead forced downstream, making the flooding there worse.
If you encounter a flooded roadway while driving you should: - Answer- stop and turn
around, do not try driving or even wading across.
The _______________ occurs when the elevation of a stream's surface exceeds that of
the stream bank. - Answer- flood stage
The number of tributaries a stream has is used in determining: - Answer- stream order.
An elevated area along a length of a stream bank is a ? - Answer- levee
Increasing the slope steepness past the _______________ increases the likelihood of a
flow-type mass movement. - Answer- angle of repose
The probability that a landslide will occur on a slope increases when both the driving
forces (gravity and loads) and the resisting forces (friction and cohesion) increase -
Answer- False
Slopes composed of soil that are fully saturated with water are susceptible to landsliding
because: (There are two possible correct answers - please click both.) - Answer- The
pore pressure of the water pushes the mineral grains apart, reducing the friction
between them, lowering the strength of the soil
Water is heavy and increases the load
A mass of material moving in coherent pieces down a defined surface is a ? - Answer-
slide
