Geology

What are the 5 basic controls of soil formation?

time, climate, plants, animals, topography.

What is the primary basis for distinguishing different chemical sedimentary rocks? How is it different from detrital rocks?

Chemical sedimentary rocks focus on mineral composition whereas detrital rocks focus on particle size.

What texture is associated with all detrital rocks?

Clastic

What minerals are most abundant in detrital sedimentary rocks?

Clay minerals and quartz

Which factor is most influential in soil formation?

Climate

Name two major resources that were largely formed in river delta environments of the geologic past?

Coal and oil

What is the difference between conglomerate and breccia?

Conglomerate is mostly gravels with rounded edges, while breccia has more jagged edges.

What are the 3 broad categories of sedimentary environments?

Continental, marine, and transitional (shoreline).

Name a type of mass wasting that happens very slowly

Creep

What are the 4 major physical processes leading to the fragmentation of rock?

Frost wedging, crystal growth, expansion resulting from unloading/sheeting, and biological activity.

Which of the following represents the greatest proportion of the freshwater on Earth?

Glaciers

What influences flow velocity?

Gradient, channel shape, channel size and roughness, and discharge.

Why does marble and granite weather so differently?

Granite is a silicate mineral, which is more resistant to chemical weathering. Marble is composed of calcite, which dissolves in weakly acidic solution, such as rainwater.

What is the controlling force of mass wasting?

Gravity

Describe the arrangement of water molecules in ice.

Hexagonal

During what season does solifluction in the Arctic occur?

High latitude summer.

What is the form of chemical weathering in which the hydrogen in water is exchanged for metallic cations in minerals called?

Hydrolysis

In what way does urbanization of a drainage area affect the timing and height of a river flood after a heavy rain event?

Occurs sooner and higher

Is a highly meandering river relatively young or old?

Old.

What of the following is least resistant to weathering?

Olivene

Catastrophic mass wasting is most likely to occur...

On steep slopes

What is the primary basis for distinguishing among detrital rocks?

Particle size

What is the "raw material" for coal and under what circumstances does it accumulate?

Peat

What is permafrost?

Permanently frozen ground in harsh subarctic regions.

What is a sandy deposit on the inside of a river meander bend called?

Point bar

What is the term for the lowest/deepest and finest-grained portion of a river delta sediment package?

Pro delta clay/mud

What is the river discharge formula?

Q=va

What happens to grain size and roundness of particles in a river channel as you proceed down stream?

Reduction of grain size and increase of roundness/range of minerals.

How is regolith different from soil?

Regolith does not contain organic matter, water, and air.

What type of mass wasting result in formation of a talus deposit?

Rock false

In what environment are rapid mass wasting processes most likely to occur?

Rugged, geologically young mountains

If the discharge of a river increases, and the velocity remains the same, what happens to the cross-sectional area?

Sediment will accumulate and cause accretion in the given area

What specific type of weathering causes the formation of a bare rock dome, such as Looking Glass Rock in the Blue Ridge Mountains of North Carolina?

Sheeting

How do slumps and rockslides differ?

Slumps do not move very fast or far, whereas rockslides are very fast and destructive

Why is soil considered an interface in the Earth system?

Soil forms where the geosphere, atmosphere, hydrosphere, and biosphere meet.

What happens to sediment being carried by a river when the flow velocity falls below the threshold and settling velocities of that size material?

The sediment will be deposited.

How might the direction a slope is facing influence soil formation?

The steeper the slope, the less water is in it, therefore the less developed the soil is.

When a rock is mechanically weathered, how does its surface area change? How does this influence chemical weathering?

The surface area increases as it gets weathered, leaving more exposed area susceptible to chemical weathering (which only occurs at the surface)

How is sediment carried if a river is flowing at a velocity greater than the settling velocity of the sediment?

The velocity is fast enough to carry the sediment in suspension, allowing it to travel further. Happens only with turbulent flow.

How do evaporites form?

They are formed of material deposited from solution by evaporation of water. Ex: halite, rock salt, gypsum.

What are two reasons that sedimentary rocks are important?

They are major energy sources (oil, natural gas, coal, uranium) and also primary reservoir of groundwater.

Why are soils in tropical rain forests not well suited for farming?

They are severely leached due to high temperature and heavy rainfall.

How might a wildfire influence mass wasting?

They cause debris flow and destabilize slopes through the destruction of plants that anchor the soil.

What is the significance of the angle of repose?

This is the steepest angle at which material remains stable.

How does an exfoliation dome form?

Through a process called unloading/sheeting: reduction in confining pressure occurs as overlying rock is eroded, causing outer parts of granitic mass to expand more than rock below.

How is carbonic acid formed in nature?

Through dissolution (ex: When carbon dioxide in the atmosphere dissolves in raindrops)

What is the term for the type of transport in which particles roll or slide along the floor of the river channel?

Traction

T or F: Alluvial fans are formed by intermittent streams that generally flower from mountains into flat, arid regions with no drainage outlet.

True

What are the 3 main soil orders in the US?

Ultisols, aridisols, mollisols. Alaska: inceptisols and gelisols.

How does water affect mass wasting processes?

Water allows gravity to more easily set the material in motion.

Explain why angular masses of rock often become spherical boulders.

When rocks become extensively jointed, they are chemically weathered on the corners and edges, which gradually become rounded and smooth boulders.

Is a river with many nickpoints a young stream or an old mature stream?

Young

What are the three main parts of a river system?

Zone of sediment production, zone of transportation, zone of deposition

What are the major processes of chemical weathering?

dissolution, oxidation, and hydrolysis (most dominant).

The problems encountered when building the bridge from the Charleston Peninsula to James Island were the result of the Ashley River's base level having been much _____ in the geologically recent past.

lower

Which is the most dominant form of physical weathering?

Frost wedging

How many calories would it take to transform 2 grams of ice as -12˚C to water vapor at 104˚C?

6 - Every calorie is a 2˚ change

At 0˚ C, what % of molecules in liquid water are bonded?

80%

What is the shape of the longitudinal (graded) profile of a river?

A slope with no nicks.

What are the basic mechanisms contributing to creeps?

Alternating expansion and contraction of surface materials caused by freezing/thawing or wetting/drying.

Gibbsite (bauxite) is the final weathering product of feldspar in hot, wet climates. What resource do we get from bauxite?

Aluminum

Name one of the environmental variables that influence the amount and rate of chemical weathering that will occur in a given locality?

Amount of precipitation

How does biological activity contribute to weathering?

As roots in plants grow, they wedge the rock apart. Burrowing animals break rock down. Decaying organisms produce acids that contribute to chemical weathering.

Why can rock avalanches move at such great speeds?

Because air becomes trapped and compresses beneath the falling mass of debris, making it more buoyant.

Explain how the formation of biochemical sediments differs from the formation of sediments formed by inorganic processes.

Biochemical sediment is formed by water-dwelling animals and plants that have extracted dissolved mineral matter to form shells and other hard parts. After they die, their skeletons become sediment.

What type of river is likely to occur when the river receives too much sediment to handle with its annual discharge, especially if the discharge varies greatly on a seasonal basis?

Braided

How are sediments sorted?

By size- those grouped with others of the same size are well sorted.

What are the most common cements?

Calcite, silica, and iron oxide.

What is the difference between earthflows and debris flows?

Debris flows are usually in confined channels in semiarid regions, and earthflows are on hillsides in humid areas during times of heavy rain or snowmelt.

If a river's base level is raised, what happens to the competence of that river?

Decreases

What is the top portion of a delta, which is covered with lush vegetation, called?

Delta plain

What are the three basic sedimentary rock categories?

Detrital, chemical, and organic.

What is the correct term for the pattern of stream channels that develops on a delta?

Distributary

What terms are used to describe the way material moves during mass wasting?

Fall, talus slopes, slides, flow, rock avalanche (most common).

Compaction is most important as a lithification process with which sediment size?

Fine grained

What size material can be starting into motion at the lowest threshold velocity?

Fine sand

How do joints promote weathering?

Fractures produced by expansion/contraction allow water to penetrate and begin weathering process before rock is exposed.

What type of mechanical weathering result from the volume increase (expansion) as water crystallizes to ice?

Frost wedging

Where is the greatest amount of chemical weathering likely to occur?

In a wet, tropical environment

Explain how water can cause mechanical weathering.

In frost wedging, ice can crack rocks by working its way into cracks of rock as a liquid, then breaking off as it freezes. In salt crystal growth, salt content in water penetrates rock. As water evaporates, crystals gradually grow on the area, weakening the rock by pushing surrounding grains apart.

What products result when carbonic acid reacts with potassium feldspar?

It breaks down into the clay mineral kaolinite.

What is diagenesis?

It is a term for chemical, physical, and biological changes that happen after sediments are deposited during/after lithification.

What occurs when carbonic acid reacts with calcite-rich rocks such as limestone?

It is easily attacked by weakly acidic solution.

What is the most resistant to the effects of weathering?

K-feldspar

Which type of mass wasting is the most dangerous and deadly?

Lahar

Contrast laminar and turbulent flow.

Laminar flow is planar, and turbulent flow is chaotic

Distinguish among limestone, dolostone, and chert.

Limestone, the most abundant chemical sedimentary rock, is composed mainly of calcite. Dolostone, composed of dolomite, can be distinguished from limestone because is not as reactive to hydrochloric acid as limestone is. Chert is made of microcrystalline quartz, and has variations such as flint, agate, and jasper.

What are the two basic categories of weathering?

Mechanical and chemical

How does mechanical weathering differ from chemical weathering?

Mechanical weathering uses physical forces, rather than chemical transformations of rock, to break the rock into smaller pieces.

Is the greatest velocity in a river at the surface along the inside of a meander bend?

No

What is diurnal/seasonal volume change?

Not a dominant form of mechanical weathering- mostly a result of temperature and not water. It happens most with dark mineral grains due to heat.

What type of geologic event are we humans trying to prevent with regard to the Mississippi River and the Atchafalaya River?

Stream piracy

What dangerous and damaging byproduct results from oxidation of sulfide ores?

Sulfuric acid

List several minerals that are especially susceptible to oxidation and list two common products of oxidation.

Susceptible minerals include olivine, pyroxene, hornblende, and biotite. Common products of exfoliation are hematite and limonite.

What are the two major things that will determine amount of weathering?

Temperature and annual precipitation

How does climate influence weathering?

Temperature and moisture are the main factors in weathering- warm temperatures with high moisture are best for weathering. Frigid areas are bad for weathering, as moisture is locked.

What river has the greatest annual discharge?

The Amazon

What is evapotranspiration?

The combined process of evaporation and transpiration that involves the transfer of water from the surface directly to the atmosphere.

With regard to a river, what does the term competence refer to?

The largest particles a river will carry.

What is the relationship between earthquakes and landslides?

The movement of unstable soil may trigger a mass waste movement.