Geology 105 Exam 2
Paving over land decreases the amount of flooding because water can't soak into the soil
False
Soil erosion is not a present day problem in the US...
False
The main societal impact of soil erosion is that the eroded soil ends up filling our water reservoirs and diminishes our drinking water supply.
False
There has never been a globally catastrophic volcanic eruption from Iceland's volcanoes because they only involve gentle lava flows
False
Unfortunately, volcanoes do not give any signs or indications of when they might erupt
False
A _____ is a relatively flat lowland that borders a river, usually dry but subject to flooding every few years
Floodplain
After a watershed is urbanized, flood discharges typically
Increase
How would a river in an area changed from forest to farmland react to changes?
Increased amounts of sediment would increase the gradient of the stream
Urbanization has several impacts on the natural processes of flooding along a river. Building or paving over land creates an impervious or impermeable surface that
Increases the runoff directly into the river, thereby increasing the flooding
Soils on the central and high plane in the US are known as...
Mollisols
Where on a river would you most likely find point bars?
On the inside of a bend
Where does a meandering river run the fastest?
On the outside of a bend
Where on a river would you most likely find cutbanks and why?
On the outside of a bend because that is where the river erodes most
The erosion process in a river is directly related to:
The velocity of the flow
Composite volcanoes can have a long dormant period in which people can forget that they were ever once active volcanoes
True
Despite the fact that modification of the natural course of a river by engineering its course is always a major impact on the surrounding environment, some drainage projects are beneficial in flood control.
True
Earthquakes cause subsidence because tectonic plates involved in subduction can actually snap downward after stress is released in an earthquake.
True
Humans have contributed to the thawing of permafrost through poor building practices.
True
If levees are built along a river to protect a town such as St. Louis, then the narrowing in the width of the channel between the levees can cause the floodwater to back up and increases the level of flooding upstream.
True
In areas undergoing subsidence due to the overpumping of groundwater, flooding can be a major problem.
True
Insurance and building codes are two important ways that the government can protect property from disaster in a flood
True
Magma with a higher silica content will also have a higher viscosity
True
Meandering rivers migrate over time across their floodplain and actually create their floodplains by eroding and depositing sediment over time.
True
Minerals that forms last in the Bowen series tend to be generally more stable and resist better to weathering
True
One of the benefits of flooding is deposition of fertile soil
True
People have successfully diverted lava flows from populated areas
True
The bed load of a stream involves the largest grains in the stream
True
The recurrence interval for a river in a natural system to reach bankfull stage is about one to two years.
True
The result of chemical weathering is a change in the composition of the original material
True
If the average velocity of streamflow is 5 feet per second, and the cross-sectional area of the stream channel is 20 square feet, what is the stream discharge (assume that you do not change any of the units of either velocity or area when you perform this computation)(just give the number WITHOUT units)?
100
If the geologic mapping of a particular volcano shows that violent explosive eruptions occurred in the years 1600, 1620, 1680, 1800, 1805, 1895, 1910, 1955, and 2000, the recurrence interval for this volcano is
50 years
A soil is...
A mixture of air, minerals, water, and organic matter
In the following list of magmas, only one will produce a lava dome - the others will produce lava flows or spatter to form small cinder cones or explode to produce pyroclastics. Which one of the following magmas is most likely to produce a lava dome when it reaches the Earth's surface?
A rhyolitic magma without gas
What is avulsion?
A river shifts its position after a flood
What is subsidence?
A sinking of the ground surface
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?
An andesitic magma with gas
The watershed ( or drainage basin) is:
An area that drains into a specific river and limited by the drainage divide
What is the definition of soil according to a soil scientist?
Any solid earth material that has been altered by physical, chemical, and organic processes so that it can support rooted plants
Where is the majority of lava extruded?
At divergent plate boundaries
Which one of the following is NOT mechanical weathering? A.Frost wedging B.Dissolution C.Exfoliation D.Biologic action
B.
Which of the three common lavas has the lowest viscosity?
Basaltic
Which of the following loads are most likely to consist of heavy rocks and boulders?
Bed load
What two parameters are plotted in a hydrograph?
Discharge vs. time
Which of the following is NOT a normal definition of soil erosion? A.Grain-by-grain removal of mineral and organic material in a soil by wind and water B.Removal of soil material at an unacceptable rate C.Dissolution of flowing acidic groundwater to produce a large underground opening D.Removal of soil material at a rate faster than it is being produced
C.
Which of the following is NOT usually caused by land subsidence or soil volume change? A.Water pollution B.Building collapse C.Disease D.Coastal flooding E.Loss of wetlands
C.
Yellowstone is considered to be a "supervolcano" - capable of producing an eruption several thousand times the size of the Mt. St. Helens eruption. Yet, most people don't even realize it is a volcano - all you see is a big hole in the ground! This type of volcano is known as a
Caldera
What causes volume change in expansive soil?
Changes in the water content
Factors affecting soil formation are...
Climate, parent material, biological action, and time
What is the main difference between collapse sinkholes and solutional sinkholes?
Collapse sinkholes involve the surface rock and soil falling into an underground cave whereas solutional sinkholes form by downward dissolution from the bedrock surface.
What is the difference between a crater and a caldera?
Craters are formed from explosions while calderas are formed from inward collapse of volcano tops
Measures to prevent soil erosion include:
Crop rotation, contour plowing, windbreaker, and runoff control
In which of the following tectonic plate settings are volcanoes typically NOT found? A. Mid-ocean ridge B.Continental rift C.Subduction zone D.Transform fault E.Hotspot
D.
Which of the following is NOT an example of how urbanization influences a river or stream? A.Urbanization decreases rainwater infiltration into the ground and therefore increases the frequency of floods B.Urbanization decreases rainwater infiltration into the ground and therefore increases the magnitude of floods C.Urbanization decreases flood lag time by the network of street sewers D.Urbanization increases rainstorm frequency and therefore increases the frequency of floods
D.
Rills and Gullies are...
Deep incisions produced by running water that scour and erode the soil
What is a hydrograph NOT able to tell you about a river? A.The stage or discharge of a river at a particular time B.Size of a river flood C.How the stage or discharge of a river varies over time D.The highest discharges or stages for rivers over a period of time E.The amount of rainfall an area receives
E.
Which of the following does NOT cause ground subsidence? A.Dissolving of rocks below the Earth's surface B.Earthquakes C.Thawing of permafrost D.Compaction of loose sediment E.Creation of permanently frozen ground where no thawing ever occurs
E.
Which of the following is FALSE about magma? A.Most magmas come from melting of the asthenosphere B.Some magma comes from rocks melted through decompression C.Adding volatiles, such as water, to rock decreases its melting point and makes it easier to melt D. Some rocks are melted from magma that is rising from deep within the earth E.Tectonic plates move around on an underground ocean of magma
E.
Which of the following is NOT a benefit of volcanoes to the earth and its inhabitants? A.Volcanic soils have minerals that grow certain types of plants B.Volcanic processes can create valuable deposits of metals and minerals that are useful for building C.Volcanoes are beautiful and provide areas for recreation D.Heat from volcanoes can be harnessed to produce energy E.Many of the world's major oil fields are in volcanic rock
E.
Which of the following is NOT a reason why stratovolcanoes are dangerous? A.They are associated with higher viscosity magma B.They have dormant periods between eruptions, which can make people underestimate their hazard C.They erupt abundant pyroclastic debris D.They involve explosive eruptions E.They erupt fast-moving lava flows that kill many people
E.
Which statement is FALSE about the effects that floods can have? A.Floods can supply nutrients to soils for farming B.Floods can clear ecosystems of debris C.Floods can supply sediments to build up the elevation of land D.Floods can bring nutrients to ecosystems E.Flooding has no positive effects;it is always bad for human interests
E.
If a volcanic eruption is predicted for your area, what is the best course of action?
Evacuate
In an undisturbed environment, soils...
Evolve through time and increase in thickness
Delaware is unlikely to experience significant flooding in the future.
False
Expansive soils are relatively rare and cause little if any damage to structures.
False
Like earthquakes, volcanic eruptions occur without warning and, although there are precursors, they cannot reliably be used to determine what is going on beneath the ground
False
Magma and lava are basically the same thing...
False
Formation of a soil includes processes that acts...
From the top, down
In which "reservoir" of the Earth's hydrologic cycle is most of the world's freshwater stored?
Glaciers
Which of the following is NOT a readily dissolvable rock?
Granite
Mature soil...
Has numerous recognizable horizon
Which of the following volcanic areas are located at a mantle hotspot?
Hawaii and Yellowstone
What is the stage of a river?
Height of water that is flowing
Which of the following will tend to REDUCE the size of a river flood?
High rate at which the precipitation soaks into the ground
Which of the following factors contributes the most to the elevated flood hazards in North and South Dakota, along the Red River?
Ice and ice dams
Where does the majority of soil originate from?
It comes from weathered rock
Intense farming is potentially dangerous for soil conservation because...
It disrupt the natural vegetation cover and expose the soil material
The effect of physical weathering may enhance the action of chemical weathering because...
It fractures the rock and offer more surface for chemical reactions
Where does tephra come from?
It is the volcanic rock and lava blasted into the air or carried by gases
The time that intercourse between the peak of precipitation and the peak of a flood at any given point along the river is known as the
Lag time
What is the name of a volcanic mudflow?
Lahar
The next time you are in the market to buy a house, you will...
Make sure that you have flood insurance,build or renovate the house to be flood-resistant, check to make sure that it isn't located on the 100 year floodplain
Do humans affect the frequency or size of volcanic eruptions?
No. People do not increase or decrease the volcanic hazard
Where is the best place to be during a pyroclastic flow?
Nowhere is safe during a pyroclastic flow
Although we focus on the hazardous aspects of volcanoes in this class, they also provide significant natural service functions. Which of the following are considered benefits of volcanic activity?
Nutrient rich soils, ore deposits, potential for geothermal power
Which of the following is the correct link between the soil and its horizon classification?
O is organic material.
In which reservoir of the Earth's hydrological cycle is most of the world's water stored?
Oceans
How does pumping oil contribute to land subsidence?
Oil is removed, which removes the buoyant support it provided for the earth material, causing it to be more compacted.
Which one of these eruptions is likely to produce a tall column of steam, ashes and tephra that can reach the upper layer of the atmosphere?
Plinian eruption
The explosion of magma at the Earth's surface produces what type of volcanic material?
Pyroclasts
Along the coast, in proximity of major river, a beach is usually made by a very high concentration of quartz sand because....
Quartz is more resistant than other minerals and is what remains after the weathering processes have disintegrated and dissolved the sediments
How good of an indicator is soil color in categorizing the soil horizon?
Reasonably good. Sometimes color can be misleading, but usually it can give you a good idea.
Which rivers have the highest gradient?
Rivers moving down mountains
The chemical weathering process known as hydrolysis affects mostly which type of minerals?
Silicates
How are sinkholes related to water pollution?
Sinkholes provide a quick route for polluted surface water to contaminate groundwater.
Mt. St. Helens in Washington is an example of which type of volcano?
Stratovolcano
Which volcano type involves layers of pyroclastic debris and lava flows?
Stratovolcano
Andesite is most commonly found at what type of plate tectonic setting?
Subduction zones (convergent)
The disaster at Lake Nyos in Cameroon (Africa) is thought to have been caused by a...
Suffocating cloud of carbon dioxide gas
What component of the hillslope hydrological cycle provides the most direct control on flooding (pick from one of the following: interception, evapotranspiration, infiltration, groundwater flow, surface runoff)?
Surface runoff
Most of the explosive magma produced on Earth is produced by the process of subduction and is andesitic to rhyolitic in composition. Your book discusses the three processes by which a rock can melt to form a magma. Which of the following processes is responsible for producing the andesitic/rhyolitic magma seen at subduction zone volcanoes?
The addition of water to the hot rock of the mantle
Most of the magma produced on earth is produced at mid-oceanic ridges (divergent plate boundaries) to form the oceanic crust and is basaltic in composition. Your book discusses the three processes by which a rock can melt to form a magma. Which of the following processes is responsible for all the basaltic magma at the ridges?
The decrease in pressure on the hot rock in the mantle as it upwells toward the surface.(Decompression melting)
How would the hydrograph of a large rainstorm change after urbanization of an area?
The peak of the hydrograph would become higher and narrower
Several communities around Mt. Rainier are built on enormous old lahar deposits. What might people in these areas expect in an eruption?
Their homes will probably be destroyed by a new lahar
If you were in a very cold climate and looking out at an area with many sinkholes and rough terrain, what would you most likely be looking at?
Thermokarst
What happens to rivers when they reach their base level?
They often form alluvial fans or deltas
The U.S. National Flood Insurance Program, and FEMA regulations, require participating communities to do what?
To prohibit all new construction within the floodway and to map the 100 year floodplain to determine flood hazard areas
After a flood, you should be sure to wash anything that has been in touch with river water
True
In a region susceptible to sinkhole formation, the most likely times for collapse will be...
When groundwater levels are low
Why do scientists study earthquakes to predict a volcanic eruption?
When magma moves, it causes earthquakes
