Geol105 Exam 2

True or False: Because of the alert systems and people's willingness to heed warnings, no one was killed in the 1980 Mt. St. Helens eruption.

False

True or False: During a flood, the safest place to be is behind a levee or floodwall.

False

True or False: Flash floods are most common on the floodplains of large meandering rivers.

False

True or False: Flash floods are usually of short duration and therefore not very dangerous.

False

True or False: Hydrographs are used to show the amount of water in the hydrologic cycle.

False

True or False: If you live on the 100 year floodplain, it means that you are guaranteed to have one large flood once every 100 years.

False

True or 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 (hint: think of what scientist were able to do in during the Pinatubo eruption)

False

True or False: Magma and lava are basically the same thing...

False

True or False: Mudflows or lahars associated with volcanoes do not usually cause much damage in a volcanic eruption because they are constrained to river valleys.

False

True or False: Paving over land decreases the amount of flooding because water can't soak into the soil.

False

True or False: Shield volcanoes are the most dangerous volcanoes because they are so big.

False

True or False: There have never been any caldera eruptions in the U.S. and probably won't be in the future.

False

True or False: Unfortunately, volcanoes do not give any signs or indications of when they might erupt.

False

True or False: Volcanic soils are usually too hot and dry to be of use for agriculture.

False

True or False: Volcanoes associated with high viscosity magma are usually less dangerous than those with more freely flowing magma

False

True or False: Volcanoes associated with high viscosity magma are usually less dangerous than those with more freely flowing magma.

False

True or False: A river in flood stage can erode and transport more sediment than the same river in normal flow.

True

True or False: After a flood, you should be sure to wash anything that has been in touch with river water.

True

True or False: An alluvial fan can be found at the base level of rivers.

True

True or False: At a river meander, erosion occurs on the outside part of the bend, and deposition occurs on the inside part of the bend.

True

True or False: Construction of levees can actually make floods worse in areas upstream and downstream from the construction.

True

True or False: Heat from volcanic areas can be used to generate electrical power.

True

True or False: If a basaltic lava flow were coming toward you, you could probably outrun it.

True

True or False: If the discharge of a river is constant and the river channel suddenly widens, then the velocity of the river will decrease.

True

True or False: Mauna Loa in Hawaii is an example of a shield volcano built over a hotspot.

True

True or False: Most volcanoes are found near tectonic plate boundaries because that's where the magma is located.

True

True or False: One of the benefits of flooding is deposition of fertile soil.

True

True or False: The bed load of a stream is involves the largest grains in the stream.

True

True or False: Tributaries are smaller streams which drain into larger rivers.

True

Ture or False: Tephra can come in many different sizes from dust size to large pieces called bombs.

True

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 ___ years.

50 years

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? A. An andesitic magma with gas. B. A basaltic magma without gas. C. A basaltic magma with gas. D. A rhyolitic magma without gas.

A. An andesitic magma with gas.

Which of the following lists magma types in order of increasing viscosity (LEAST viscous first)? A. Basaltic, andesitic, rhyolitic B. Basaltic, rhyolitic, andesitic C. Rhyolitic, basaltic, andesitic D. Rhyolitic, andesitic, basaltic E. Andesitic, rhyolitic, basaltic

A. Basaltic, andesitic, rhyolitic

Which of the following natural hazards is the number 1 disaster in the United States in terms of lives lost over the past century? A. Floods B. Volcanoes C. Earthquakes D. Landslides E. Lightning

A. Floods

Which of the following states has the greatest percentage of karst topography? A. Kentucky B. Nevada C. Nebraska D. Louisiana E. Alaska

A. Kentucky

Which one of these eruptions is likely to produce a tall column of steam, ashes and pyroclastic that can reach the upper layer of the atmosphere? A. Plinian eruption B. Hawaiian eruption C. Pelean eruption D. None of the above

A. Plinian eruption

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? (Choose all that apply.) A. Potential for geothermal power B. Ore deposits C. A reduction of carbon dioxide in the atmosphere leading to global cooling. D. Nutrient rich soils

A. Potential for geothermal power B. Ore deposits D. Nutrient rich soils

Mauna Loa in Hawaii is an example of which type of volcano? A. Shield volcano B. Composite cone C. Lava dome D. Cinder cone E. Stratovolcano

A. Shield volcano

In the past 50 years, have there been any deaths attributed to a volcanic eruption? A. Yes. Thousands of people have died as a result of an eruption. B. Yes. A few unfortunate people have been killed due to volcanic eruptions. C. No. All people were given enough warning and nobody has been killed in recent times. D. No. Recent volcanic eruptions have been in remote areas where there were no deaths. E. No. There have been no volcanic eruptions in recent times.

A. Yes. Thousands of people have died as a result of an eruption.

What is the role of a drainage basin? A. Rivers empty into a drainage basin, which represents a lake or the ocean. B. A drainage basin is the area drained by a river and all of its tributaries. C. A drainage basin is very permeable soil into which flood waters seep instead of going into a river. D. A drainage basin is very impermeable soil, where flood waters are held and eventually evaporate instead of going into a river. E. A drainage basin is a set of underground tunnels that drain water into the ocean.

B. A drainage basin is the area drained by a river and all of its tributaries.

What is the floodplain? A. The area around a river that is the ultimate limit to how far it will ever flood B. A flat area next to the river carved out by the rivers C. The steep sides of the river channel that holds in the water D. Earthen mounds that run parallel to the river and hold in the water during floods E. A triangular shaped deposit that forms when a river flows into the ocean

B. A flat area next to the river carved out by the rivers

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. A basaltic magma without gas. B. A rhyolitic magma without gas. C. A basaltic magma with gas. D. An andesitic magma with gas.

B. A rhyolitic magma without gas.

Which is NOT a location where volcanoes are found? A. Alaska B. Central United States C. Hawaii D. Pacific Northwest United States E. Yellowstone National Park

B. Central United States

Which of the following volcanic areas are located at a mantle hotspot? A. Mt. St. Helens and Mt. Fuji B. Hawaii and Yellowstone C. Augustine and Pinatubo D. Mt. Rainier and Vesuvius

B. Hawaii and Yellowstone

Which of the following will tend to REDUCE the size of a river flood? A. High amount of precipitation in a drainage basin B. High rate at which the precipitation soaks into the ground C. Fast rate at which the runoff moves towards the river D. High amount of moisture in the soil (water-saturated soil)

B. High rate at which the precipitation soaks into the ground

What is the best reason why most lava flows aren't a threat to human life? A. Most lava flows don't move into inhabited areas. B. Lava flows usually don't flow very quickly, people can outrun them. C. Lava stays in the volcano and generally doesn't flow. D. Lava flows are not hot enough to kill people, just to burn them.

B. Lava flows usually don't flow very quickly, people can outrun them.

At which plate boundary is more viscous lava found? A. Oceanic hotspots B. Oceanic subduction zones C. Oceanic divergent plate boundaries D. Continental rift zones E. Shield volcanoes on the ocean floor

B. Oceanic subduction zones

At which plate boundary is more viscous lava found? A. Oceanic hotspots B. Oceanic subduction zones C. Oceanic divergent plate boundaries D. Continental rift zones E. Shield volcanoes on the ocean floor

B. Oceanic subduction zones

Mt. St. Helens in Washington is an example of which type of volcano? A. Shield volcano B. Stratovolcano C. Caldera D. Cinder cone

B. Stratovolcano

Mt. St. Helens in Washington is an example of which type of volcano? A. Shield volcano B. Stratovolcano C. Caldera D. Cinder cone

B. Stratovolcano

Which of the following loads would make a river appear murky or dirty? A. Bed load B. Suspended load C. Dissolved load D. Structural load E. Buoyant load

B. Suspended load

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 A. cinder cone B. caldera C. shield volcano D. stratovolcano E. lava dome

B. caldera

In which cycle do rivers NOT play an important role? A. hydrologic cycle B. tectonic cycle C. rock cycle D. biogeochemical cycle

B. tectonic cycle

Which of the three common lavas has the lowest viscosity?

Basaltic

What would the longitudinal profile of a river flowing from a gentle valley into an ocean look like? A. A steeply downward sloping line B. A steeply upward sloping line C. A gently downward sloping line D. A gently upward sloping line E. An upward sloping and then downward sloping line

C. A gently downward sloping line

Where is the majority of lava extruded? A. At subduction zones B. At hotspots C. At divergent plate boundaries D. At transform plate boundaries E. At convergent plate boundaries

C. At divergent plate boundaries

Where does the majority of soil originate from? A. It comes from magma from the mantle. B. It comes from volcanoes. C. It comes from weathered rock. D .It is brought up from the ocean floor. E. It is produced by humans.

C. It comes from weathered rock.

What is the difference between magma and lava? A. Magma is molten rock, lava is hot solid rock and water. B. Magma is black, lava is red. C. Magma is found below the Earth's surface, lava is found on the Earth's surface. D. Magma is found on the ocean floor, lava is found on land surfaces. E. There is no difference between lava and magma.

C. Magma is found below the Earth's surface, lava is found on the Earth's surface.

Which of the following are things that you should NOT do in preparing for a flood? A. Buy flood insurance. B. Place sandbags to block water from entering doors. C. Make a flood kit and place it in your basement. D. Make a flood plan with members of your household. E. Find out how to turn off utilities in the event of a flood.

C. Make a flood kit and place it in your basement.

What is the greatest hazard to people in a flash flood? A. Sediment deposits B. Erosion of farmland C. People driving into floods and being carried away D. Houses and other buildings being carried away E. Fires

C. People driving into floods and being carried away

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 this basaltic magma at the ridges? A. The increase in temperature as heat is added to hot rocks in the Earth's crust. B. The addition of water to the hot rock of the mantle. (Changing chemistry) C. The decrease in pressure on the hot rock in the mantle as it upwells toward the surface. (Decompression melting) D. The increase in pressure on the hot rock of the mantle during downwelling.

C. The decrease in pressure on the hot rock in the mantle as it upwells toward the surface. (Decompression melting

Where are the majority of the active volcanoes in the United States? A. Washington, Oregon and California B. Wyoming and Idaho C. Hawaii D. Alaska E. There are NO active volcanoes in the United States.

D. Alaska

Which volcano type is composed mostly of pyroclastic debris? A. Shield volcano B. Stratovolcano C. Lava dome D. Cinder cone E. Composite cone

D. Cinder cone

Which of the following adverse effects of natural hazards is NOT associated with flooding? A. Pollution B. Disease C. Destruction of buildings D. Land upheaval E. Economic loss

D. Land upheaval

Which of the following was NOT a hazard associated with the explosion of Mt. St. Helens? A. Landslide B. Mudslide C. Ash fall D. Lava flows that built up the north side of the volcano

D. Lava flows that built up the north side of the volcano

Does it have to be raining for a river to flood? A. Yes. Only the rain that falls into the river fills it up and causes it to overflow. B. Yes. Rain runs off over the ground and into the river causing flooding. C. No. Snow and rain that fall into the river fill it up and cause it to overflow. D. No. Rivers can flood after rain has stopped and tributaries have flowed into bigger streams. E. No. Rivers can flood during droughts without any rain.

D. No. Rivers can flood after rain has stopped and tributaries have flowed into bigger streams.

Which of the following volcanic hazards is responsible for the most deaths? A. Lava flows B. Ash falls C. Poisonous gases D. Pyroclastic flows

D. Pyroclastic flows

Which of the following volcanic hazards is responsible for the most deaths? A. Lava flows B. Ash falls C. Poisonous gases D. Pyroclastic flows

D. Pyroclastic flows

How good of an indicator is soil color in categorizing the soil horizon? A. Excellent. Color always indicates an exact soil horizon. B. It is an excellent indicator of soil horizon for well-drained soils but a poor indicator for poorly-drained soils. C. Terrible. Different soil horizons don't have distinct color differences. D. Reasonably good. Sometimes color can be misleading, but usually it can give you a good idea.

D. Reasonably good. Sometimes color can be misleading, but usually it can give you a good idea.

Which rivers have the highest gradient? A. Rivers near their base level B. Rivers near the ocean C. Rivers in gentle valleys D. Rivers moving down mountains

D. Rivers moving down mountains

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? A. The increase in temperature as heat is added to hot rocks in the Earth's crust. B. The decrease in pressure on the hot rock in the mantle as it upwells toward the surface. C. The increase in pressure on the hot rock of the mantle during downwelling. D. The addition of water to the hot rock of the mantle.

D. The addition of water to the hot rock of the mantle.

Why do cinder cone volcanoes have steep slopes? A. They are made from lava flows that pile up steeply. B. They are found near other volcanoes which crowds their ability to spread out. C. They are made mostly from water and ash that hardens into steep cones. D. They are made from pyroclastic materials that pile up near where they were erupted. E. They are made from very thick magma that doesn't flow outward very much.

D. They are made from pyroclastic materials that pile up near where they were erupted.

What happens to rivers when they reach their base level? A. Their discharge decreases. B. They erode sediment. C. They fill the bottom of a v-shaped valley. D. They often form alluvial fans or deltas.

D. They often form alluvial fans or deltas.

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. Transform fault

Andesite is most commonly found at what type of plate tectonic setting? A. mid-oceanic ridges (divergent) B. hot spots (intraplate) C. continental collisions (convergent) D. subduction zones (convergent) E. strike-slip faults (transform

D. subduction zones (convergent)

The disaster at Lake Nyos in Cameroon (Africa) is thought to have been caused by a A. volcanic eruption that created a giant water wave, which flooded nearby areas. B. volcanic eruption that created a landslide, which in turn created a giant water wave that flooded nearby areas. C. volcanic eruption that destroyed a dam, which flooded nearby areas. D. suffocating cloud of carbon dioxide gas.

D. suffocating cloud of carbon dioxide gas.

Which volcano type is composed mostly of pyroclastic debris? A. Shield volcano B. Stratovolcano C. Lava dome D. Cinder cone E. Composite cone

D.Cinder cone

In which of the following cases would you expect the LEAST amount of flooding due to a rainstorm? Assume all areas receive similar amounts of rainfall in the rainstorm and there are no flood control measures in any of the areas. A. An area where soil is already saturated due to previous recent thunderstorms B. An area where the ground is frozen C. A short duration rainstorm falling on an area that is typically very dry such as a desert D. A city with many houses, paved roads, and sidewalks E. A long duration rainstorm falling on an area that consists of forest, grasslands, and no human development.

E. A long duration rainstorm falling on an area that consists of forest, grasslands, and no human development

In terms of soil development, what factor is most important in determining whether a soil is weakly, moderately, or well-developed? A. Climate B. Parent material C. Mineral type D. Moisture amounts E. Age

E. Age

Choose the best answer. Which would increase during a flood, discharge or velocity? A. Discharge only because there is more water flowing B. Velocity only because the water is flowing faster C. Neither discharge or velocity because the stream will be doing more erosion during a flood D. Neither discharge or velocity because both are constant for any given stream E. Both discharge and velocity will increase because there is more water flowing and it is flowing faster.

E. Both discharge and velocity will increase because there is more water flowing and it is flowing faster.

If a volcanic eruption is predicted for your area, what is the best course of action? A. Board up your windows and doors B. Bring food and water into your basement and stay there C. Build a firebreak around your home D. Build a moat around your home E. Evacuate

E. Evacuate

In which two environments are shield volcanoes found? A. Hotspots in the ocean and subduction zones B. Hotspots on land and divergent plate boundaries C. Divergent plate boundaries and subduction zones D. Hotspots on land and subduction zones E. Hotspots in the ocean and divergent plate boundaries

E. Hotspots in the ocean and divergent plate boundaries

Which of the following is NOT a reason why people live near volcanoes? A. They don't think that they will erupt. B. They don't have anywhere else to go. C. The soil is good for farming. D. It is their home. E. Local zoning laws require some people to live near volcanoes.

E. Local zoning laws require some people to live near volcanoes.

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. Many of the world's major oil fields are in volcanic rock.

Do humans affect the frequency or size of volcanic eruptions? A. Yes. Global warming is a direct cause of many volcanic eruptions. B. Yes. More people living on volcanoes causes volcanoes to erupt. C. Yes. More people in the area of volcanoes means less groundwater in those areas and that causes volcanoes to erupt. D. Yes. Mitigation measures by humans keep many volcanoes from erupting. E. No. People do not increase or decrease the volcanic hazard.

E. No. People do not increase or decrease the volcanic hazard.

Where is the best place to be during a pyroclastic flow? A. In the water B. In your house C. On a hillside D. In a valley E. Nowhere is safe during a pyroclastic flow.

E. Nowhere is safe during a pyroclastic flow.

Which of the following is NOT a reason why an ash fall can be hazardous? A. Destroys crops and makes the ground unsuitable for planting B. Contaminates water supplies C. Accumulates on building roofs causing them to collapse D. Gets into jet engines causing them to fail E. Sets on fire everything it touches

E. Sets on fire everything it touches

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. Tectonic plates move around on an underground ocean of magma.

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. The amount of rainfall an area receives

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. They erupt fast-moving lava flows that kill many people.

Which of the following does NOT usually affect the development of most soil? A. Climate B. Time C. Organic processes D. Landslides E. Topography

E. Topography

Which of the following natural hazards is NOT caused by volcanoes? A. Climate change B. Landslides C. Fire D. Tsunami E. Tornadoes

E. Tornadoes

What is the name of a volcanic mudflow?

Lahar

The explosion of magma at the Earth's surface produces what type of volcanic material? (one word)

Pyroclasts