GY 102 Learnsmart Ch 12

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Order the materials below based on their likely angle of repose relative to each other. (Place the material with the highest angle of repose at the top.)

1. Coarse, angular sand that is slightly wet 2. Dry, partially round, fine sand 3. Clay flakes that are saturated with water

Order the materials below based on their likely angle of repose relative to each other. (Place material with the highest angle of response at the top.)

1. Coarse, angular sand that is slightly wet 2. Dry, partially round, fine sand 3. Clay flakes that are saturated with water

Identify the examples of biotic weathering listed below. (Select all that apply.)

A bear digs into the soil and loosens rock, A species of lichen living on a rock secretes a chemical that slowly dissolves the rock.

How did Carlsbad Caverns in New Mexico form?

A large reed in a warm sea formed a limestone deposit, which later dissolved as acids leaked into it from underlying petroleum accumulations.

Which of the following locations would be expected to have the highest degree of chemical weathering?

A shady, flat slope with abundant vegetation

Select the areas in the United States where karst topography is common. (Select all that apply.)

Along belts of folded rocks in and near the Appalachian Mountains, Florida

Which of the following factors would tend to increase the depth of weathering (and thickness of soils) in an area? (Select all that apply.)

An increase in rainfall, Higher temperatures, An increase in plant growth

You are studying a large rock outcrop in the U.S. that has both a southern and a northern exposure. Why might the weathering of this rock be different on the two sides?

Because the southern side is likely sunnier and drier, physical weathering may dominate in this location.

What type of material dominates the downslope movement of a debris flow?

Boulders and gravel in mud

Why is carbonic acid the most important agent of chemical weathering despite being a weak acid?

Carbon dioxide and water are abundant in the atmosphere, so carbonic acid is present in all rainfall.

What features are indicators of rock dissolution? (Select all that apply.)

Cavities, Pits

The Slumgullion landslide is located in the San Juan Mountains of ___: it originates in high elevation, steep peaks dominated by ___ rocks.

Colorado; igneous

What type of slope failure is indicated by the image shown here?

Creep

Geologists who studied the 1999 debris flow disaster in Caraballada, Venezuela, found that destroyed buildings has been built upon older debris flows. How can this information be used for the future? (Select all that apply.)

Data suggests that debris flows are normal events for this area, Future development in this area should either be minimized or done with very careful planning.

Which of the following are hazards associated with living on an active alluvial fan? (Select all that apply.)

Debris flow, Flash flooding

Which of the following are possible causes for submarine slope failure? (Select all that apply.)

Earthquakes, Volcanic eruptions, Sediment overloading

___ is the movement of weathered materials. If this movement of weathered materials happens in a downslope direction due to the force of gravity, we call it ___.

Erosion; mass wasting

True or false: An area with steep slopes and highly weathered bedrock is a good place to build and is not likely to have future slope failure.

False

True or false: How a mineral weathers depends only on the climate in which it is located.

False

What type of material typically is involved in the downslope fluid motion of an earth flow?

Fine-grained soils

Significant deposits of clay minerals typically accumulates in what types of environments? (Select all that apply.)

Floodplains, Deltas, Lake bottoms

Select the areas in the United States where karst topography is most common. (Select all that apply.)

Florida, Along belts of folded rocks in and near the Appalachian mountains

Select geologic features that can be formed when groundwater interacts with limestone. (Select all that apply.)

Flowstone, Sinkholes, Caves

What event triggered the Vaiont Dam rock slide disaster?

Heavy rainfall

What will eventually happen to material on a steep slope if it is internally weak and poorly attached to the hillside?

It will fall and move downslope.

What is the global distribution of karst topography?

Karst is very widespread globally and occurs on populated continents

Significant deposits of clay minerals typically accumulate in what types of environments? (Select all that apply.)

Lake bottoms, Deltas, Floodplains

___ cause 25 to 50 annual fatalities in the United States. (Use just one word.)

Landslides

Which of the following are characteristics of karst topography? (Select all that apply.)

Limestone pillars, Sinkholes, Caves, Dessappearing streams

Which of the following indicates an area might have a high potential for slope failure? (Choose all that apply.)

Loose material that is relatively weak; Evidence of past slope failures in an area with known problems; Steep slopes or recent changes in slopes; Potential triggers in the area such as possible earthquakes and volcanic eruptions

Weak acids formed in water can cause changes in the rocks and minerals with which they interact. Identify those changes below. (Select all that apply.)

Loosen mineral grains, Dissolve rocks and minerals, Result in the formation of clay minerals

In which of the following settings would you expect to find a thick exposure of soil?

One in which conditions favor extensive weathering

What is the general term used for the rocks and minerals acted upon by physical and chemical weathering?

Parent material

___ breaks rocks into smaller pieces without changing their composition.

Physical weathering

Match the rock type with the correct descriptions of its solubility and how it most commonly weathers.

Quartzite: Very low solubility, Weathers physically Limestone: Very soluble, Prone to chemical weathering

Weak acids formed in water can cause changes in the rocks and minerals with which they interact. Identify those changes. (Select all that apply.)

Result in the formation of clay minerals, Loosen mineral grains, Dissolve rocks and minerals

Which of the following describes the process of unloading?

Rocks fracture as overlying rock is removed

A weathered landscape would likely have which of the following features? (Select all that apply.)

Rounded sediments, Thick soils in areas with extensive weathering

What key factor is Florida lacking that results in a low overall risk for landslides?

Steep slopes

Which of the following best describes the relationship between rate of movement in the Slumgullion landslide and precipitation?

The failure moves more slowly in drier periods.

How does time affect weathering?

The more time, the more weathering occurs.

Why are geomorphologists often some of the first people to arrive at the location of a recent, large slope failure? (Select all that apply.)

They are involved in assessing the potential for future danger from the same type of event, They want to collect data in order to understand how the event happened

Select the accurate summary below of time's influence on weathering.

Time is a critical factor in that it allows for more weathering to occur.

What evidence is shown on this photograph that suggests the Slumgullion landslide has not or is not moving rapidly?

Trees are growing on the landslide material.

Which of the following is indicative of a slow slope failure?

Trees on top of the slope are alive yet tilted

True or false: A pile of rocks at the base of a hill suggests that slope failure has occurred.

True

True or false: Plants can be agents of physical weathering, breaking rocks apart.

True

What is biotic weathering?

Weathering causes by biological activity

Rocks with ___ may weather rapidly because fractures and bedding planes provide a pathway for water into the rocks.

abundant discontinuties

Rainwater is slightly ___ because it contains dissolved carbon dioxide and sulfur dioxide and will dissolve limestone if the two are in contact.

acidic

The steepest angle at which a pile of unconsolidated grains remains stable is called the ___.

angle of response

Secondary minerals that form the chemical weathering of other minerals ___.

are more stable than the original minerals

In general and over time, weathering will tend to cause rock features to ___.

become more rounded

What types of evidence are geologists looking for when trying to locate prehistoric slope failures? (Select all that apply.)

bedding and structures that are at a different tilt or orientation than surrounding outcrops, debris pile that are different in type from the immediate landscapes, hummocky topography

The tombstone in the image has a white streak that extends down its face from a metal plate. The most likely cause of the darker areas around this white streak is ___.

biotic weathering

Limestone is easily dissolved by weak acids because it is composed primarily of the mineral ___.

calcite

Limestone is primarily composed of ___.

calcium carbonate

The presence of limestone on a surface, sinkholes, and other features of karst topography may indicate that there are ___ at depth.

caves

The hydrosphere is essential for ___ weathering because oxygen dissolved in water oxidizes iron in rocks, and carbon dioxide mixed with water forms carbonic acid, which breaks down minerals in rocks.

chemical

How a mineral weathers depends on time of exposure, the surrounding climate, and the mineral's ___. (Select all that apply.)

chemical composition, atomic structure

The weathering of feldspar found in granite can create both dissolved ions and ___ minerals.

clay

The very slow yet continuous movement of earths materials downslope is classified as ___. (Use just one word.)

creep

A very rapidly moving, turbulent mass of debris, air, and water is known as a ___.

debris avalanche

The alternating ledges and slopes shown in this photograph are the result of ___ weathering, as some of the rock layers are more susceptible to weathering than others.

differential

Slope failure, or mass wasting, is movement in which bedrock, rock debris, or soil moves ___ in response to the pull of ___.

downhill; gravity

Geologists help to mitigate damage from slope failures by ___. (Select all that apply.)

examining evidence of past slope failures, identifying areas that have a high potential for future failure

As rocks are uplifted to the surface, ___ may form as the rock cools and pressure is released.

expansion joints

A debris slide moves downhill more coherently than a debris _____, which contains more water and usually is a more disordered movement.

flow

Rock slides commonly occur in rock outcrops that ___.

have discrete layers that are oriented parallel to the direction of downhill movement

The upper end, or ___, of a rock slide marks where the slide pulled away from the rest of the hill.

head

Minerals that crystalize at ___ temperatures inside Earth are unstable at Earth's surface and weather easily

high

Limestone is composed of calcite, a mineral that dissolves easily in ___ climates.

humid

What are the three types of soil water?

hygroscopic water, capillary water, gravitational water

Excessive water increases the susceptibility of a slope to failure by adding weight and by ___.

increasing pore pressure and pushing the grains further apart

The type of fracture, which is small and has no significant offset, promotes weathering by allowing water and plant roots to penetrate the rock.

joint

Sinkholes, disappearing streams, and limestone pillars are characteristics of __ topography.

karst

La Conchita, California, is unsuitable for permanent housing because ___.

landslides have occurred there in the past and will occur there in the future

Caves, travertine, and karst topography are formed when groundwater interacts with ___.

limestone

Travertine is a sedimentary rock that is formed when ___ that was dissolved in groundwater reprecipitates when the groundwater flows onto the surface.

limestone

The Slumgullion landslide, as well as other geologic hazards, are best studied with the use of detailed ___. These then can be used to share information. (Use just one word for your answer.)

maps

Specific rock properties that influence weathering include the grain size and ___ composition, as well as the types and numbers of discontinuities, such as fractures and bedding planes.

mineral

Data collected from the Slumgullion landslide were used to create a computer ___ to better understand the movement of the materials.

model

In general, limestone located in a wet climate will weather ___ limestone in a dry climate.

more rapidly than

We use the terms slump and rotational slide to describe slope failures that ___.

move along curved surfaces with some backward rotation of the material

Oxidation of minerals usually occur ___.

near Earth's surface

Oxidation of minerals usually occurs ___.

near Earth's surface

Gravity (shown by the thickest arrow) can be broken into two component forces: the ___ component, which is perpendicular to the slope, and the ___ component, which is parallel to the slope.

normal; shear

Rock broken into ___ pieces increases the amount of surface area on which chemical weathering can occur.

numerous and small

The process of ___ occurs when minerals react with oxygen at or near Earth's surface.

oxidation

As the rate of physical weathering increases, the amount of chemical weathering also increases because ___.

physical weathering increases the amount of surface area on which chemical weathering can occur

Geologists assess the ___ slope failure by studying slope steepness, rock condition, and possible triggers.

potential for

The outer zone of a rock that has been weathered is called the weathering ___.

rind

The salt content of water is referred to as its ___.

salinity

A debris slide occurs as unconsolidated materials move downhill in a semicoherent mass, leaving behind a low ___ on the hillside.

scarp

The new minerals that form as a result of chemical weathering at Earth's surface are more stable than the original minerals. These minerals are referred to as ___ minerals.

secondary

Another name for a rotational slide is a(n) ___.

slump

A(n) ___ hangs from the ceiling of a cave, and a(n) ___ grows upward from the floor.

stalactite; stalagmite

As physical weathering occurs, the amount of ___ area of a rock outcrop increases, and this allows more ___ weathering to occur.

surface; chemical

The angular blocks of rock near the bottom of a hill or mountain are called ___.

talus

When groundwater is carrying dissolved limestone and that groundwater flows onto the surface, ___ is formed.

tavertine

When ocean water evaporates, ___.

the dissolved salts remain in the sea

Caves and caverns can be formed by the dissolution of limestone by flowing ___.

water

In a sequence of rocks that is susceptible to rock slide failure, detachment commonly occurs along the base of a(n) ___ rock, such as shale or salt.

weak

Most of the salt in the oceans is derived from ___.

weathering of rocks on land

The global abundance of limestone and other soluble rocks explains why karst topography is ___.

widespread

What is the general term commonly applied to the slow to very rapid movement of rock or soil downslope?

Landslide

Slope failures can be triggered by different types of specific events, including ____. (Select all that apply.)

precipitation, slope modification, earthquakes

Expansion joints are formed from either cooling or the release of ___ as rocks are uplifted to the surface.

pressure

The work geologists do in studying recent and prehistoric slope failures help to mitigate the loss of life and ___ from future slope failures.

property

Select the scenario that most likely explains how the cave pictured here formed.

A less resistant rock weathered and eroded more quickly to form the cave and a more resistant rock remains to form the roof.

___ are soils formed from wetlands without permafrost. They are susceptible to being compacted but are very fertile.

Histosols

Geologists used GPS to determine what information regarding the Slumgullion landslide?

How fast it was moving

Why is hydrolysis an important process in affecting the salinity of oceans?

Hydrolysis reactions produce the sodium and potassium ions that form common salts.

Which of the factors listed below likely played an important role in the failure of this slope in California? (Select all that apply.)

Intense rainfall, Highway construction, Costal erosion

Although debris and rock ___ vary in the size and types of materials that compose each, both can move very quickly and are extremely hazardous.

avalanches

Given the forces shown here, the block will most likely ___.

begin to slide downslope

Through the process of hydrolysis, K-feldspar combines with slightly acidic water and converts into ___.

clay minerals

The alternating ledges and slopes shown in this photograph are the result of ___ weathering, as some of the rock layers are susceptible to weathering than others.

differential

___ form(s) in some limestone caves as water flows down the walls and forms travertine in thin layers that can become thicker over time.

flowstone

Managing the number of animals grazing, using "no till" agriculture practices, and strip cropping are ___ techniques for soil erosion management.

preventative

Tilted fence posts, curved tree trunks, and bedrock layers bent downslope are all indicators of ___.

soil creep

Chemical weathering is generally more intense on the corners and edges of a block of rock, resulting in the rock becoming rounded. This weathering feature is known as ___ weathering.

spheroidal

The primary difference between debris and rock avalanches is ___.

the composition of the material involved

Slope failures are common secondary hazards of ___ eruptions that cause shaking, tilting, and fracturing of the ground.

volcanic

Even though the steepness of the Slumgullion landslide is reduced significantly from the head to the toe, the failure continues because of the abundant ___ in the materials.

water

Flowstone or draperies are formed in caves when travertine precipitates out of ___ that is flowing down cave walls or along the cave floors.

water

Flowstone or draperies are formed in caves where travertine precipitates out of ___ that is flowing down cave walls or along the cave floors.

water

The natural, erosive action of ___ often removes the toe of a slope and causes failure because of oversteepening.

water

The process of hydrolysis occurs when minerals combine with ___.

water

Chemical and physical ___ causes the breakdown of surface materials. This process increases slope instability, thus increasing the likelihood of gravity causing mass ___.

weathering; wasting

The fatalities connected with the Vaiont Dam disaster were caused ___.

when a rock slide created large waves that overtopped the dam

Studies show that the rate of movement in the Slumgullion landslide decreases in the ___.

winter

Which of the following outcrops has the greatest potential for rock slide failure?

Layers of shale and sandstone with a moderate dip

How does mineral wedging occur?

Minerals precipitate in joints and exert an outward force on rocks as they grow into crystals.

Match the soil horizon letter (O, A, E...) with the description of what type of soil is in the layer.

O: Surface litter: Organic litter A: Topsoil: Humus, organisms, inorganic E: Zone of leaching: Chemically weathered B: Subsoil: Accumulated material from above C: Regolith: Weathered bedrock or unconsolidated sediment R: Bedrock

Weathering is the change in the physical and chemical character of rock exposed at Earth's surface. Identify the ways in which physical (mechanical) and chemical weathering can be differentiated from one another. (Select all that apply.)

Physical weathering involves breaking rock apart, whereas chemical weathering involves the breakdown of minerals in a rock; Rocks subjected to physical weathering do not change in composition, whereas rocks undergoing chemical weathering do not change in composition

What process forms the shape displayed in exfoliation domes?

The occurrence of exfoliation joints that run parallel to the rock's surface

How are evaporite rocks associated with karst topography?

They are soluble in water and so can dissolve to form karst topography.

How do lava tubes (pictured here) form?

They form as the lava that flowed in the tunnel drained out of it.

Which of the factors listed below make the Pacific Northwest particularly vulnerable to damage from debris flow? (Select all that apply.)

Heavy annual precipitation, High elevations steep slopes, volcanic activity

Geologists used carbon-14 to determine what information regarding the Slumgullion landslide?

How long ago the failure began

Slope failure classification is based upon which of the three following characteristics?

The type of material involved, The rate of movement, How the material is moving

Match the sections of the Slumgullion landslide to their descriptions.

The upper part: Scarps are present where the land is pulling away from the adjacent rocks. The sides and middle: Linear to gently curved zones of shearing are present at boundaries behind sections moving with different velocities. The toe (lower part): Parts of the slide are overriding material that has not slipped or slipped as much.

How are weathering and mass wasting related?

The weathering of earth materials loosens them, increasing the likelihood of downslope movements by mass wasting.

How do joints influence the development of a landscape? (Select all that apply.)

They affect the strength of the rocks, They decrease a rock's resistance to weathering, They decrease a rock's resistance to erosion

How do joints influence the development of a landscape? (Select all that apply.)

They decrease a rock's resistance to weathering, They affect the strength of the rocks, They decrease a rock's resistance to erosion

Match each of the types of physical weathering with its description. Unloading Frost Wedging Thermal Expansion Plant growth

Unloading: Formation of joints due to the removal of overlying rock and subsequent expansion. Frost wedging: Widening of cracks in rock by water expanding as it freezes to ice. Thermal expansion: Heating and cooling that causes minerals to expand and contract differently. Plant growth: Widening of cracks by expanding tree roots.

Which of the following types of information do geologists use to study the Slumgullion landslide in Colorado?

Weather records, Soil horizon thicknesses, Aerial photographs, Physical properties of landslide materials

Slope ___ and altitude affect the degree and type of weathering a rock undergoes.

aspect

Feldspar in granite may become sand in conditions where chemical weathering is minimal, such as in ___ climates.

dry

The Slumgullion slope failure is typically called a landslide, but it could be categorized as a(n) ___ flow because it is composed mostly of fine-grained materials.

earth

Soil on slopes resist downslope movement due to the ___ component of gravity.

shear

Collapse of the roof of a cave can produce a(n) ___.

sinkhole

Which of the following are surface features that may indicate caves at depth? (Select all that apply.)

sinkholes, presence of limestone, disappearing streams

A(n) ___ is a class of slope failure that involves a relatively intact block of material moving along a well defined plane. A(n) ___ involves material free-falling or bouncing down a cliff. (Hint: Put one word in each blank.)

slide; fall

The Gros Ventre slope failures that occurred in Wyoming in 1925 is one of the largest rock ___ ever in the U.S. A 1.5km long slab of limestone was involved.

slides

A(n) ____ hangs from the ceiling of a cave, and a(n) ___ grows upward from the floor.

stalactite; stalagmite

Minerals formed at depth within Earth may be unstable at the surface due to very different ___ conditions. (Select all that apply.)

temperature, moisture, pressure

Flowstone or debris are formed in caves when travertine precipitates out of ___ that is flowing down cave walls or along the cave floors.

water


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