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G301
slope, stream, groundwater
93
Geology
Undergraduate 4
03/13/2012

Additional Geology Flashcards

 


 

Cards

Term
Name the runoff pathways
Definition

-Overland flow

-Subsurface (storm)flow

-Return flow + saturation overland flow

-Deep Groundwater

Term
Erosion process types are dependent on what?
Definition

Climate

vegitation

land use

Term
Detatchment and transport of soil is known as what?
Definition
Surface erosion
Term
Name the two major processes and agents that cause surface erosion.
Definition

Water

wind

Term
What kind of erosion happens when the rainfall rate is greater than the infiltration capacity? 
Definition
Sheetwash erosion
Term
What kind of runoff do you get when the rainfall rate is greater than the infiltration capacity?
Definition
overland flow (olf)
Term
In sheetwash erosion, the erosive force is a function of what 5 things?
Definition

-depth of water

-length of slope

-resistance by soil texture

-cohesion

-vegetation

Term
Concentration of water can lead to deeper erosion and form one of these two.
Definition

-rills

-gullies

Term
The teton dam failure in June of 1976 was an example of this type of erosion.
Definition
Piping erosion
Term
If a surface is nearly bare, this type of erosion is possible.
Definition
-Wind erosion
Term
What holds soil particles together and shields from splash & wash?
Definition
Vegetation
Term
There are 7 things that rates of erosion depend on. 
Definition

-soil characteristics

-climate

-topopgraphy: slope gradient, length etc.

-presence & type of vegetation

-animal activity

-land uses

-erosion control practices

Term
Erosion that moves as a unit with little or no deformation within the sliding mass is called what?
Definition
A Slide
Term
Erosion that moves as a unit and are thoroughly deformed internally during movement are called what?
Definition
Flows
Term
What is the difference between slides and flows?
Definition
Slides move as one solid unit with little/no deformation when flows thoroughly deform during movement.
Term
total surface erosion is equal to the sum of these 3 things
Definition

-combined rainsplash

-sheetwash

-rill/gully

 

Term
What are the 3 processes to consider for measuring erosion volume or rate?
Definition

-Surface process measurements

-River-basin scale

-Geologic evidence

Term
What are some factors (3 of them) due to animal activity that affect erosion rates?
Definition

-ants & termites

-Burrowing/soil transfer

-grazing (affects veg & surface)

Term
What is the definition of mass movement?
Definition
Downslope transfer of rock & soil under the influence of gravity.
Term
Name the 6 types of mass movement.
Definition

1) Falls

2) Topples

3) Slides

4) Lateral spreads

5) Flows

6) Complex

Term
what caused the largest lanslide in history?
Definition
1980 eruption of mtount st. helens
Term
Movement parallel to planes of weakness and occasionally parallel to the slope is what type of movement?
Definition
Slide
Term
Gradual movement of slope materials is called what?
Definition
Creep
Term
The end-over-end motion of rock down a slope is called?
Definition
Topple
Term
Viscous to fluid-like motion of debris is called what?
Definition
Flow
Term
A sporadic and sudden channelized discharge of water and debris is called what?
Definition
Torrent
Term
Curved or rotational failure known as slump can be catagorized as what?
Definition
slide (landslide)
Term
failure due to shear stress > shear strength causes what?
Definition
landslides
Term
lateral movement of cohesive material over a deforming mass of soft low-cohesion material.
Definition
lateral spread
Term
what is the failure surface(type of slope) and movement usually like for a lateral spread?
Definition

failure surface = parallel to ground surface on gentle slopes

motion is fast to very fast

Term
What is an important factor of flows? And what is the range of speed flows can move at?
Definition
Important factor is water content and they move from very slow to very fast
Term
Creep to flow in debris with ice is known as a...
Definition
rock glacier
Term
Solifluction
Definition
Creep in seasonally melted layer over permafrost
Term
A slide followed by conversion to flow is known as what kind of movement?
Definition
complex movement (more than one type)
Term
When and where is the largest rock/debris/ice avalnche?
Definition
Kolka (Caucasus) in 2002
Term
What is a submarine slide/flow?
Definition
It is a process affected by mixing with water
Term

factor of safety is a ratio of what?

 

(FOS < 1) =movement 

Definition

sum of forces resisting movement (Fr)

sum of forces tending to movement (Fd)

Term
Loss of strength in bedrock is caused by what?
Definition

-weathering (physical and/or chemical)

-planes of weakness (bedding, joints, faults, etc)

Term
what is the angle of repose?
Definition
it is the angle of internal friction
Term
name two unconsolidated materials talked about when referring to mass movement.
Definition

-soils

-regolith

Term
unconsolidated material are affected by what?
Definition

-grain size & shape

-sorting

-mineral composition (clay)

-water

Term
non-cohesive soils have a frictional resistance to _____
Definition
shear
Term
what is cohesion?
Definition
molecular forces between minerals/grains (especially clays)
Term

What is the typical angle of internal friction of:

-fine sand

-coarse sand

-angular pebbles

 

Definition

-35 degrees

-40 degrees

-45 degrees

Term
what engineering tool is used to analyze cohesive and non-cohesive soils?
Definition
mohr's circle
Term
How does water affect unsaturated materials?
Definition
water is in tension which usually makes the situation more stable.
Term
How does water affect saturated materials?
Definition
it reduces strength, reduces friction between grains & surfaces, and buoyancy pushes particles apart.
Term
name 4 natural events that are immediate causes/triggers of mass movement.
Definition

-rapid water input from rain or snowmelt

-shock/vibration

-sudden change in slope geometry (undercutting)

-change in vegetation (fire+water ---> debris flow)

Term
Method of slices helps search for the smallest what?
Definition
factor of safety
Term
name 3 stability models/programs
Definition

L1SA

Xstabl

Slope/W

Term
Name the 5 processes that cause increased shear stress.
Definition

1) Removal of lateral support

2) Addition of weight to the slope (surcharge)

3) Earthquakes

4) regional tilting

5) Removal of underlying support

Term
Name the 3 processes that reduce shear strength
Definition

1) Physical and chemical weathering processes

2) Increases in fluid pressure within soil

3) Progressive creep/tree roots and animals burrowing

Term
What type of tree is an indicator of a past landslide?
Definition
Alder tree.
Term
What is the main thing to at to make the assumption of a past lanslide?
Definition
vegetation
Term
Name 3 engineering methods for landslide prevention.
Definition

-changing slope geometry or material strength via removal of unstable material or by using rock bolts

-Structures such as retaining walls, fences and other barriers

-Change the slope hydrology via drainage or dewatering

Term
where are the highest 3 percentages of water on earth?
Definition

oceans @96.5%

ice, sno, permafrost @1.76%

Soil & Groundwater @ 1.7%

Term
name the 4 runoff pathways
Definition

1-overland flow

2-subsurface flow

3-return flow + saturation overland flow

4-deep groundwater

 

Term
runoff processes & properties depend on what 4 things?
Definition
climate, vegetation, geology, topography
Term
What does a dendritic drainage network pattern look like?
Definition
It looks like nerves 
Term
what is a radial drainage network pattern?
Definition
The drainage off of a volcano that breaks into separate streams.
Term
What is stream flow affected by?
Definition

-Friction of the bed & banks

-Manning's roughness coefficient

Term
equation for wetted perimeter?
Definition
area of the x-sec/depth of the x-sec (m or ft)
Term
What is Basal shear stress?
Definition
The force exerted on the bed of the stream.
Term
Streams entrain matter (sediment) as what 3 things?
Definition

-Dissolved load

-Suspended load

-Bedload

Term
When talking about stream beds, what is competence?
Definition
maximum size particle that can be carried.
Term
when talking about stream beds, what is capacity?
Definition
total load that can be carried.
Term
water/discharge and sediment load are in ______ equilibrium.
Definition
dynamic
Term
waterfalls cause longitudinal ______
Definition
erosion
Term
braided streams commonly are found where? What type of sed load? What kind of banks?
Definition
mountains, deserts, and glacial. The have variable discharge. Heavy & coarse sed load and steeper slope.
Term
Meandering streams are commonly found where? What kind of sed load? What type of Q?
Definition
Lowlands. Usually have less & finer sed load and a more regular Q with more veg on the bank for stabilization.
Term
Columbia, Klamath, Fraser across the cascades and coast ranges are examples of ________ streams?
Definition
Antecedent streams
Term
The early cenozoic era was how many years ago (range)?
Definition
65-20Ma years ago
Term
how many years ago was the mid cenozoic, later cenozoic and quaternary eras?
Definition

-20-15Ma

-15-2Ma

-2Ma-present

Term
the flood-basalt catastrophes happened in what cenozoic era?
Definition
mid-cenozoic
Term
the pnw we recognize happend in what era?
Definition
Quaternary era (2Ma-present)
Term
This terrane underlies the coast ranges & willamette valley and contain oceanic basalt.
Definition
Siletz-Crescent terrane (55-45Ma)
Term
what kind of minerals will you find in the coast ranges of oregon? (two types of ___stones)
Definition
sandstones & siltstones
Term
Major volcanism in the western cascades contributed volcanic ash to the shelf sediments, also known as....
Definition
tuffaceous
Term
The western cascades are over the _______ zone?
Definition
subduction
Term
what basalts are on top of the grande ronde basalts?
Definition
the Wanapum basalts
Term
Name the areas of around Portland that Columbia River Basalts underlie.
Definition

Tualatin Mountains (West Hills), cascade foothills, etc.

They are also in the columbia gorge.

Term
how long has the willamette valley been a topographic low?
Definition
over 15Ma
Term
The late micene to pliocene era was how long ago?
Definition
10-2 Ma
Term
rhododendron Fm (12-8Ma)
Definition
Lavas & breccias from western cascades
Term
Lower Troutdale Fm (8-4 Ma)
Definition

Coarse, cemented gravels and sands

sands&silts

deposited by the columbia

eastern source: quartzites, micas

Term
sedimentation & volcanism happened in what era?
Definition
late cenozoic
Term
uplift of cascades and coast range, initiation of high cascade volcanism (boring lava volcanoes in portland area) happened when?
Definition
Late cenozoic, after 4Ma
Term
what plate produced the modern cascade volcanic arc?
Definition
Juan De Fuca plate
Term
boring lavas happened in what period/time frame?
Definition
late cenozoic (3.5-50Ka)
Term
mt tabor is a cinder cone with boring lava and high cascades volcanics.
Definition
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