Term
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Definition
-Overland flow
-Subsurface (storm)flow
-Return flow + saturation overland flow
-Deep Groundwater |
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Term
| Erosion process types are dependent on what? |
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Definition
Climate
vegitation
land use |
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Term
| Detatchment and transport of soil is known as what? |
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Definition
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Term
| Name the two major processes and agents that cause surface erosion. |
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Definition
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Term
| What kind of erosion happens when the rainfall rate is greater than the infiltration capacity? |
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Definition
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Term
| What kind of runoff do you get when the rainfall rate is greater than the infiltration capacity? |
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Definition
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Term
| In sheetwash erosion, the erosive force is a function of what 5 things? |
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Definition
-depth of water
-length of slope
-resistance by soil texture
-cohesion
-vegetation |
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Term
| Concentration of water can lead to deeper erosion and form one of these two. |
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Definition
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Term
| The teton dam failure in June of 1976 was an example of this type of erosion. |
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Definition
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Term
| If a surface is nearly bare, this type of erosion is possible. |
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Definition
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Term
| What holds soil particles together and shields from splash & wash? |
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Definition
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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 |
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Term
| Erosion that moves as a unit with little or no deformation within the sliding mass is called what? |
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Definition
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Term
| Erosion that moves as a unit and are thoroughly deformed internally during movement are called what? |
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Definition
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Term
| What is the difference between slides and flows? |
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Definition
| Slides move as one solid unit with little/no deformation when flows thoroughly deform during movement. |
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Term
| total surface erosion is equal to the sum of these 3 things |
|
Definition
-combined rainsplash
-sheetwash
-rill/gully
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Term
| What are the 3 processes to consider for measuring erosion volume or rate? |
|
Definition
-Surface process measurements
-River-basin scale
-Geologic evidence |
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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) |
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Term
| What is the definition of mass movement? |
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Definition
| Downslope transfer of rock & soil under the influence of gravity. |
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Term
| Name the 6 types of mass movement. |
|
Definition
1) Falls
2) Topples
3) Slides
4) Lateral spreads
5) Flows
6) Complex |
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|
Term
| what caused the largest lanslide in history? |
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Definition
| 1980 eruption of mtount st. helens |
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Term
| Movement parallel to planes of weakness and occasionally parallel to the slope is what type of movement? |
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Definition
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Term
| Gradual movement of slope materials is called what? |
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Definition
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Term
| The end-over-end motion of rock down a slope is called? |
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Definition
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Term
| Viscous to fluid-like motion of debris is called what? |
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Definition
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Term
| A sporadic and sudden channelized discharge of water and debris is called what? |
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Definition
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Term
| Curved or rotational failure known as slump can be catagorized as what? |
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Definition
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|
Term
| failure due to shear stress > shear strength causes what? |
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Definition
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Term
| lateral movement of cohesive material over a deforming mass of soft low-cohesion material. |
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Definition
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|
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 |
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Term
| What is an important factor of flows? And what is the range of speed flows can move at? |
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Definition
| Important factor is water content and they move from very slow to very fast |
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Term
| Creep to flow in debris with ice is known as a... |
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Definition
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Term
|
Definition
| Creep in seasonally melted layer over permafrost |
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Term
| A slide followed by conversion to flow is known as what kind of movement? |
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Definition
| complex movement (more than one type) |
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|
Term
| When and where is the largest rock/debris/ice avalnche? |
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Definition
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|
Term
| What is a submarine slide/flow? |
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Definition
| It is a process affected by mixing with water |
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|
Term
factor of safety is a ratio of what?
(FOS < 1) =movement |
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Definition
sum of forces resisting movement (Fr)
sum of forces tending to movement (Fd) |
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Term
| Loss of strength in bedrock is caused by what? |
|
Definition
-weathering (physical and/or chemical)
-planes of weakness (bedding, joints, faults, etc) |
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|
Term
| what is the angle of repose? |
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Definition
| it is the angle of internal friction |
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|
Term
| name two unconsolidated materials talked about when referring to mass movement. |
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Definition
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|
Term
| unconsolidated material are affected by what? |
|
Definition
-grain size & shape
-sorting
-mineral composition (clay)
-water |
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|
Term
| non-cohesive soils have a frictional resistance to _____ |
|
Definition
|
|
Term
|
Definition
| molecular forces between minerals/grains (especially clays) |
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|
Term
What is the typical angle of internal friction of:
-fine sand
-coarse sand
-angular pebbles
|
|
Definition
-35 degrees
-40 degrees
-45 degrees |
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|
Term
| what engineering tool is used to analyze cohesive and non-cohesive soils? |
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Definition
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|
Term
| How does water affect unsaturated materials? |
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Definition
| water is in tension which usually makes the situation more stable. |
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|
Term
| How does water affect saturated materials? |
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Definition
| it reduces strength, reduces friction between grains & surfaces, and buoyancy pushes particles apart. |
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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) |
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|
Term
| Method of slices helps search for the smallest what? |
|
Definition
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|
Term
| name 3 stability models/programs |
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Definition
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|
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 |
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|
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 |
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|
Term
| What type of tree is an indicator of a past landslide? |
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Definition
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|
Term
| What is the main thing to at to make the assumption of a past lanslide? |
|
Definition
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|
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 |
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|
Term
| where are the highest 3 percentages of water on earth? |
|
Definition
oceans @96.5%
ice, sno, permafrost @1.76%
Soil & Groundwater @ 1.7% |
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|
Term
| name the 4 runoff pathways |
|
Definition
1-overland flow
2-subsurface flow
3-return flow + saturation overland flow
4-deep groundwater
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|
Term
| runoff processes & properties depend on what 4 things? |
|
Definition
| climate, vegetation, geology, topography |
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|
Term
| What does a dendritic drainage network pattern look like? |
|
Definition
|
|
Term
| what is a radial drainage network pattern? |
|
Definition
| The drainage off of a volcano that breaks into separate streams. |
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|
Term
| What is stream flow affected by? |
|
Definition
-Friction of the bed & banks
-Manning's roughness coefficient |
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|
Term
| equation for wetted perimeter? |
|
Definition
| area of the x-sec/depth of the x-sec (m or ft) |
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|
Term
| What is Basal shear stress? |
|
Definition
| The force exerted on the bed of the stream. |
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|
Term
| Streams entrain matter (sediment) as what 3 things? |
|
Definition
-Dissolved load
-Suspended load
-Bedload |
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|
Term
| When talking about stream beds, what is competence? |
|
Definition
| maximum size particle that can be carried. |
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|
Term
| when talking about stream beds, what is capacity? |
|
Definition
| total load that can be carried. |
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|
Term
| water/discharge and sediment load are in ______ equilibrium. |
|
Definition
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|
Term
| waterfalls cause longitudinal ______ |
|
Definition
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|
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. |
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|
Term
| Meandering streams are commonly found where? What kind of sed load? What type of Q? |
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Definition
| Lowlands. Usually have less & finer sed load and a more regular Q with more veg on the bank for stabilization. |
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|
Term
| Columbia, Klamath, Fraser across the cascades and coast ranges are examples of ________ streams? |
|
Definition
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|
Term
| The early cenozoic era was how many years ago (range)? |
|
Definition
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|
Term
| how many years ago was the mid cenozoic, later cenozoic and quaternary eras? |
|
Definition
-20-15Ma
-15-2Ma
-2Ma-present |
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|
Term
| the flood-basalt catastrophes happened in what cenozoic era? |
|
Definition
|
|
Term
| the pnw we recognize happend in what era? |
|
Definition
| Quaternary era (2Ma-present) |
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|
Term
| This terrane underlies the coast ranges & willamette valley and contain oceanic basalt. |
|
Definition
| Siletz-Crescent terrane (55-45Ma) |
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|
Term
| what kind of minerals will you find in the coast ranges of oregon? (two types of ___stones) |
|
Definition
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|
Term
| Major volcanism in the western cascades contributed volcanic ash to the shelf sediments, also known as.... |
|
Definition
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|
Term
| The western cascades are over the _______ zone? |
|
Definition
|
|
Term
| what basalts are on top of the grande ronde basalts? |
|
Definition
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|
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
|
|
Term
| The late micene to pliocene era was how long ago? |
|
Definition
|
|
Term
|
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 |
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|
Term
| sedimentation & volcanism happened in what era? |
|
Definition
|
|
Term
| uplift of cascades and coast range, initiation of high cascade volcanism (boring lava volcanoes in portland area) happened when? |
|
Definition
|
|
Term
| what plate produced the modern cascade volcanic arc? |
|
Definition
|
|
Term
| boring lavas happened in what period/time frame? |
|
Definition
|
|
Term
| mt tabor is a cinder cone with boring lava and high cascades volcanics. |
|
Definition
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