GY 102 Learnsmart Ch 12
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
