Geology 1 Test 4

Course ENVS 105 (Geology) at UNCA with Jackie Langille: exam #4 covering soils, rivers, and appalchian geology.

what is physical weathering

Physical processes that break apart and loosen bedrock.

what processes cause physical weathering

Caused by water, wind, gravity, ice and plants

what is chemical weathering

Unstable minerals react with water, ions, and/or acids to alter to clay or oxides

what minerals do not go through chemical weathering

Quartz

can chemical weathing happen to all minerals?

No only unstable ones

what minerals are unstable

almost all of them EXCEPT FOR QUARTZ

what are the two reactions that produce ions and/or acids that are needed for chemical weathering

Water and carbon dioxide combine to create carbonic acid and if pyrite combines with water is creates sulfuric acid.

what is the hydrolysis reaction for k-feldspar

Feldspar breaks down into kaolinite (clay) when exposed to water and a positive hydrogen (H⁺) ion

what is the hydration reaction in chemical errosion

its when hematite rusts when exposed to water

what is the dissolution reaction in chemical errosion

its when calcite dissolves when exposed to acid

what type of errosion forms caves

chemical errosion caused by dissolution

what type of rock do caves form in

Limestone

What factors control the speed of chemical weathering

temperature and precipitation

does high temperature cause faster or slower chemical weathering

Faster

does a dry enviorment cause faster or slower chemical weathering

slower

what are ultisols

These form from chemical weathering of feldspar and iron oxide minerals 

what are inceptisols

These have not been in place long enough for chemical weathering

what are alfisols

These form from chemical weathering of feldspar

what is shear force

the force parallel to the slope pushing debris at a downward angle

how does shear force contribute to landslides

Material will slide down a slope when the shear component overcomes the normal component.

what is normal force

the component of gravity acting perpendicular to a slope, pushing a block of soil or rock into the slope, which produces frictional resistance against sliding

how does normal force contribute to landslides

it is the roadbloack to a landlside. it is the force that keeps debris on the slope.

what is gravity force

a downward pressing force that pushes material down a slope

how does gravity force contribute to landslides

it is the driving force behide the movement of debris

what is the angle of repose

steepest angle that sediement can be piled without falling

how does the size of sediment affect the angle of repose

large sediment has a steeper angle of repose and small sediement has a flatter one

how does water affect the angle of repose

Too much water reduces the angle of repose and can cause material to slide down the slope

what is bedrock foliation and how does it affect landslides

It is metamorphosed layers in the rock. They affect landslides because when the layers are parallel to a slope rocks can break off at the layers.

what is layering and how does it affect landslides

layers of different types of rock. They affect landslides because when the layers are parallel to a slope rocks can break off at the layers.

what is fracturing and how does it affect landslides

Breaks in the rock layer, it affects landslides because rocks are more likely to break off at a fracture point.

what is a rockfall

abrupt movements of rocks and boulders which move through by free-fall, bouncing, and rolling.

what is a landslide

the movement of a mass of rock, debris, or earth down a slope

what is a debris flow

These happen when the debris flows into stream or river channels.

what does water stage refer to in river monitoring

the surface level of the water relative to an arbitrary fixed point.

what does discharge refer to in river monitoring

the amount of water moving through a stream

how is discharge calculated

cross-section x velocity

what data is used to monitor rivers

discharge and stage

what does the x-axis on a hydrograph represent

time

what does the y-axis on a hydrograph represent

river discharge

what is lag time on a hydrograph

how long it takes to reach maximum discharge

Was this hydrograph recorded in an urban area or a forested area?

Urban area

Which of these lines was recorded in a forested area

line B

What factors affect lag time

the ability for water to soak into the ground

what factors affect the height of the peak on a hydrograph

how quickly water flows into the river and waters ability to soak into the ground

what is a recurrence interval

the average time between events

what is the recurrance interval of this Flood Frequency graph

100 years

what is the highest discharge amount on this Flood Frequency graph

25000

how does velocity affect errosion and deposition