Exam 5 Geo270

Front 1

Fall

Back 1

When a mass of rock, debris, or soil separates from a steeply sloping surface and rapidly moves downslope by free fall, bounding, or rolling, the movement is termed a fall.

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Topple

Back 2

A topple is a rotational movement that occurs as a block of material pivots forward about a fixed point near the base of the block.

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Slides vs flows

Back 3

Slides are the shearing displacement between two masses of material along a surface or within a thin zone of failure. Flows are thoroughly deformed internally during movement.

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Slump

Back 4

Slides that failure surfaces are curved or circular.

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slump scarp

Back 5

The rotational movement of the slump mass or block may result in a significant tilt of the upper surface of the moving block, or head, or block may result in a significant tilt of the upper part of the failure plane, which is called the scarp.

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translational slide

Back 6

If failure surfaces are planar rather than curved, the resulting movement is a translational slide.

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colluvium

Back 7

a mixture of residual and transported soil slowly moving downslope under the influence of gravity.

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lateral spread

Back 8

The slow-to-rapid lateral extensional movements of rock or soil masses are known as lateral spreads.

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creep

Back 9

When a flow travels at velocities at the slow end of the velocity scale, the process in called creep.

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debris, earh or mud flows

Back 10

The more rapid examples of flow phenomena are variously termed debris, earth, or mud flows. These processes involve the rapid to very rapid flow of materials down steep slopes.

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factor of safety

Back 11

a term describing the structural capacity of a system beyond the expected loads or actual loads.

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drainage basin

Back 12

A drainage basin is an area containing an integrated network of stream segmets that join together to form sucessively larger streams until one channel carries the entire surface flow out of the basin at its outlet.

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drainage divide

Back 13

The boundaries of river basins are drainage divides, because they separate adjacent basins. Drainage divides, which are usually ridges or other thopgraphically high areas, also separate tributary streams with a basin.

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main or trunk stream

Back 14

A river basin can be thought of as a well-defined area boundes on all sides by divides and within which all streams and rivers contribute to the flow of the main, or trunk, stream that leaves the basin.

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hydrologic budget

Back 15

The hydrologic budget of a watershed relates the quantity of water supplied to the basin through precipitation to the quantity of water leaving the basin.

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headward erosion

Back 16

All streams exhibit the tendency to extend their channels to a headward, or upstream, direction. If streams are followed upstream to the point where firset-order tributary channels just begin, the process of headward erosion can best be observed.

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stream capture

Back 17

Headward erosion is related to the process of stream capture. Streams erode headward at different rates because of the erosional resistance of the rocks or sediments they are flowing over or because one stream has a ssteeper slope than another and therefore deepens its channel at a greater rate. Because of its greater slope and energy, the first stream may divert, or capture, the second stream and all its tributaries above the pint of intersection.

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laminar flow

Back 18

At low velocities, the parallel flow paths of adjacent particles consititue laminar flow.

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turbulent flow

Back 19

As velocity increases, the parallel laminar flow paths can no longer be maintained. Instead, random velocity fluctuations in all directions arise within the flow. These perturbations of flow are caled turbulence and the resulting flow is turbulent flow.

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entrainment

Back 20

The process of entrainment usually refers to the ability of the river to pick up loose particles of material from the bed by the direct hydraulic action of flowing water. As the stream flows in its channel, the moving water exerts shearing forces uon the stationary bed. If these forces are larger than the gravitational forces tending to hold a particular particle on the stream bottom, the particle will be picked up off the bed and entrained into the flow.

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dissolved load

Back 21

Dissolved load is carried totally in solution by a stream.

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suspended load

Back 22

Of the nondissolved load of a river, the smaller particles are carried as suspended load.

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Terminal Velocity

Back 23

The rate at which particles tend to fall through a static liquid column is known as the terminal velocity

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Bed Load

Back 24

Bed load includes the particles that are too large to be transported by suspension.

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Thalweg

Back 25

Thalweg is the deepest part of the channel

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Alluvial fan

Back 26

If the gradient of a stream suddenly decreases, equations indicate that the velocity will decrease if other channel parameters remain the same. The stream gradient and velocity are suddenly decreased and sediment is deposited to form a hemiconical landform called an alluvial fan.

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delta

Back 27

A delta--the coastal counterpart of an alluvial fan, is constructed where a river enters lake or the sea.

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Longitudinal profile

Back 28

The change in gradient of a stream from headwaters to mouth is known as the longitudianl profile.

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Headwater

Back 29

The source or headwaters of a river or stream is the furthest place in that river or stream from its estuary or confluence with another river, as measured along the course of the river.

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base level

Back 30

Base level is the elevation that the downstream segment of the curve asymptotically approaches.

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Abyssal hills

Back 31

The ocean bottom slopes downward away from the rugged midoceanic ridges into a region of more subdued relief containing abyssal hills.

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Seamounts

Back 32

Isolated volcanic mountains rising from the oscen seafloor that does not reach to the water's surface.

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Guyots

Back 33

Some seamounts have flat tops rather than the typical conical shape of a volcano. Drilling of these flat-topped seamounts are termed guyots.

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Continental shelf

Back 34

Extending seaward from the coastline are gently sloping platforms called continental shelves.

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submarine canyons

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Valleys called submarine canyons cross the continental shelves. Most of these valleys are the offshore continuation of river valleys on land.

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continental slopes

Back 36

The continental shelves terminate at the upper margins of the continental slopes.

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Abyssal Planes

Back 37

The surface of the ocean bottom changes considerably in the vicinity of the continents. Rapid rates of deposition of continental sediment bury the landscape, producing abyssal plains of low relief.

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Wave height

Back 38

The vertical distance from trough to creat.

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Wave Length

Back 39

Wave length is the distance between adjacent crests or troughs.

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Wave Period

Back 40

The amount of time between passage of successive crests relative to a fixed point is the wave period.

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Wave refraction

Back 41

The decrease in velocity experienced by waves as they enter shallow water results in a change in direction of the wave called wave regraction.

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Tidal Range

Back 42

Large difference in elevation between high and low tides.

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Longshore Current

Back 43

A net flow of water parallel to the shore.

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Rip current

Back 44

Rapidly moving currents flowing directly away from the beach in a seaward direction.

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Longshore Drift

Back 45

Longshore drift is the movement of sand in the shore zone by longshore currents.

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Shoreline Spit

Back 46

The transportation of sand by longshore currents is responsible for the deposition of a pit, a thin strip of beach that extends from a point or headland across the mouth of a bay or other coastal indentation.

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Hooked Spit

Back 47

The ends of spits curve inward toward the bay, forming a hooked spit.

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Tombolo

Back 48

Tombolo is a deposition landform when the spit connects the beach and the offshore island.

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Barrier Island

Back 49

Most depositional coastlines are characterized by long, narrow islands that lie just offshore and trend parallel to the coast. Such islands are called barrier island.

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Lagoon

Back 50

Lagoons lie between the barrier islands and the mainland.

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Tidal inlet

Back 51

Periodic breaks in the barrier islands allow tidal flow between the ocean and the narrow lagoons that lie between the barrier islands and the mainland.

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Strom surge

Back 52

A rapid rise in water level generated by the winds of the storm as it approaches shore.

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jetties

Back 53

Jetties are walls built perpendicular to the shoreline in pairs at the mouths of inlets.

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groins or groynes

Back 54

Groins are walls built perpendicular to the beach for the purpose of trapping sand from longshore drift.

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Breakwaters

Back 55

Structures constructed on coasts as part of coastal defense or to protect an anchorage from the effects of both weather and longshore drift.

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Seawalls

Back 56

Structures built parallel to the shore to prevent erosion and slumping of sea cliffs or bluffs.

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Zone of accumulation

Zone of Accumulation pg 640 & Wikipedia

Back 57

Area above the firn line,where snowfall accumulates and exceeds the losses from ablation. Also defined as the part of a glacier's surface, usually at higher elevations, on which there is net accumulation of snow, which subsequently turns into firn and then glacier ice.

Front 58

Zone of ablation

Zone of Ablation pg 640 & Wikipedia

Back 58

Ablation is a term that includes both melting and sublimation in the zone of net loss of mass. Refers to the low altitude area of a glacier below firn with a net loss in ice mass due to melting, sublimation, evaopration, etc. Often contains meltwater features. Seasonally melting, deposits much sediment at its fringes. Snow and ice lost in ablation zone. Helps determine mass balance of glaciers

Front 59

equilibrium zone

Back 59

The boundary between the zones of accumulation and ablation is called the equilibrium line. A condition of equilibrium, or exact balance between accumulation and ablation, is indicated by a stable terminus.

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crevasse

Back 60

Network of vertical cracks called crevasses is commonly present (particularly where the glacier passes over a steeply sloping bedrock surface) when a complication of the flow process is caused by the brittle rupture of the upper portion of the glacier.

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terminus of Glacier

Terminus of Glacier pg 640 (Wikipedia)

Back 61

A glacier terminus, or snout, is the end of a glacier at any given point in time. Glaciers are in endless motion (although seemingly motionless to an observer), either advancing or retreating. Location of the glacier terminus is often directly related to glacier mass balance, which is based on the amount of snowfall which occurs in the accumulation zone of a glacier, as compared to the amount that is melted in the ablation zone.

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Striations due to glaciers

Striations due to Glaciers pg 643 and Wikipedia

Back 62

Erosional marks on a glaciated rock surface, produced by glacial erosion. Striations are elongated parallel to the ice-flow direction and are excellent indicators of past clacial moments. Scratches or gouges cut into bedrock by glacial abrasion, usually multple, straight and parallel, representing the movement of the glacier using rock fragments and sand grains, embedded in the base of the glacier, as cutting toosl.

Front 63

Glacial drift

Glacial Drift pg 644

Back 63

An "umbrella term" for al deposits associated with glaciers. Includes sediment deposited directly by the ice itself, as well as sediment deposited on, beneath, or in front of the ice by streams or in lakes. Glacial drift must be subdivided to account for the various depositional processes and charaterisitics of the resulting sediment.

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Glacial till pg 646

Back 64

Nonsorted, nonstratified sediment deposited by glcial ice at the base, from the interior, or from the top of a glacier.

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Proglacial lakes

pg 648 Wikipedia

Back 65

Once the meltwater from the glacier reaches the snout, it may be poonded in proglacial lakes. Formed either by the damming action of a moraine or ice dam during the retreat of a melting glacier, or by meltwater trapped against an ice sheet due to isostatic depression of the crust around the ice.

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glaciolacustrine sediment
pg 648 Wikipedia

Back 66

Sediment deposited into lakes that have come from glaciers. These lakes include ice margin lakes or other types formed from glacial erosion or deposition. Sediments in the bedload and suspended load are carried into lakes and deposited. The bedload is deposited at th elake margin while the suspended load is deposited all over the lake.

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glacial outwash pg 646, 648

Back 67

Coarse-grained sediment deposited by meltwater in front of a glacier in outwash plains or valley trains.

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eolian sediments pg 646

Back 68

Windblown sediment derived from other forms of drift. Very well sorted; grain size ranges from sand to silt (loess)

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loess

pg 649, 683

Back 69

Deposits of eolian silt are called loess. The silt fraction of the eroded material forms significant deposits known as loess. Very fine silt and clay transported by wind.

Front 70

drumlin pg 656

Back 70

Streamlined hills produced by wet-based, sliding glaciers. These hills occur in groups or fields and are subject to glacial debate. Characteristics: asymmetrical "streamlined" shape elongated in the direction of glacier flow and a composition of till sometimes deposited over a core of bedrock. Multiple origins such as erosion, deposition, or a combo of both

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Esker pg 657

Back 71

A sinuous ridge composed of poorly sorted sand and gravel. Formed by meltwater streams flowing in tunnels within or beneath a glacier. Stream channel is confined by ice walls and roof, the deposits remain as a raised mound after the ice melts. Sinuous, meandering shape of eskers is similar to subaerial stream channels.

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kame pg 657

Back 72

Isolated, commonly conical hills of sand and gravel. One way they're formed invovles the flow of meltwater into a cavity in the ice similar to a sinkhole in karst topography. The hole is gradually filled by stream deposits.

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permafrost pg 666

Back 73

Permanently frozen ground. The area of permafrost (20%) on Earth is extensive. 85% of Alaska and 50% of Canada and former U.S.S.R. (Russia kind of)

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periglacial processes pg 668

Back 74

Processes that produce distinctive landforms in climates subject to ground freezing are called periglacial processes. Dominated by freeze and thaw activity, occur in any cold climate whether or not a glacier is nearby. Areas of high elevation in the midlatitudes experince this periglacial activity. Can reach the equator if high enough elevation.

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Rock glaciers pg 670

Back 75

Alpine regions contain moving masses of debris called rock glaciers, which originate at high elevations in cirques or on slopes leading to mountain peaks. Consits of angular blocks of rubble that are produced by frost action on rock out crops and accumulate on slopes

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Talik
pg 667 Wikipedia

Back 76

Pockets of material (in the suprapermafrost zone) that never freezes. A layer of year-round unfrozen ground that lies in permafrost areas. Often occur underneath shallow thermokarst lakes and rivers

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Desert Pavement pg 676

Back 77

Regs (layer of stones or gravel) may consist of a concentrated surficial layer of closely spaced stones covering finer soils below, where this surface is known as a desert pavement. Formation of a desert pavement probably involves inflation, removal of the finer particles by wind, but also other processes such as freeze and thaw that preferentially move larger clasts to the surface.

Front 78

Entrainment by Suspension pg 678

Back 78

The threshold of entrainment by suspension is a dashed line that rises to the left, actually increasing as the wind-blown particles get smaller. See graphs in book? Not really sure how this is different from transported by suspension...

Front 79

Transport by Saltation pg 679

Back 79

One threshold of movement for grain sizes greater than 0.1 mm. Particles are launched into the air, they don't travel very far because of their greater weight. Read paragraph on pg 679.

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Transport by Creep pg 679

Back 80

When coarser sediment is moved by impact but remains in contact with the surface liked bed load in a stream.

Front 81

Possible Discussion question(s):
o Discuss the creation of the cross section of a dune (figure 16.60 and related text in book)
See Figure 16.60 on page 681

Back 81

With an increase in wind velocity, more pronounced transport of sand takes place and dunes are formed. Similar to fluvial dunes, having an asymmetric shape and a downwind direction of movement. Sand grains are transported up the gentle windward (stoss) side of the dune and are temporarily deposited near the top of the steeper lee face. Deposition occurs here because wind velocity drops as the wind passes over the dune’s crest. Deposition causes steepening of the lee face until a critical angle is reached. Grains then avalanche down the face, maintaining the lee face at the angle of response. By erosion on the stoss side and deposition on the lee side, dunes migrate downwind, although the dune frm remains constant. The steeply dipping lee-side cross beds are preserved as lithified dune sequences and provide evidence for arid climates in the geologic record.

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o Memorize Table 16.3 in the book.

draw table on back of this card

Back 82

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Front 83

o What physical processes combine to cause the flow of glaciers? card 1 of 2

See pages 640 to 643.

Back 83

1) One component of movement is derived from the visco-plastic internal deformation of ice, or the tendency of ice to flow downslope under its own weight when a sufficient thickness is achiveed. Glacial flow involves elements of both viscous and plastic behavior. A critical (yield) stress must be exceeded for a plastic material to deform. The yield stress for ice is about 100 kPA (1 bar). When glacier ice is subjected to this magnitude of stress, which can be imposed by the downslope component of the weight of the glacier, the ice will flow. Flow of glacial ice is laminar, rather than turbulent.
2) A second major component of glacier movement, which may take place along with visco-plastic flow, is basal sliding. Tendency of a glacier to slide as a block above its bed is dependent upon the thermal condition at the base or the ice. Because the thermal conductivity of ice is low, a glacier several km thick insulates the geothermal heat constantly flowing upward toward the land surface. Cold-based glaciers move by visco-plastic flow only. Wet-based glaciers are decouple from their beds by the presence of water between the ice and the bed, and therefore slide upon their beds.

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o What physical processes combine to cause the flow of glaciers? card 2 of 2

See pages 640 to 643.

Back 84

3) Accelerating flow is common above the equilibrium line (where ice is thickening), and decelerating flow occurs below the equilibrium line (where the ice is thinning or advancing upslope).

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Concept : What is the effect of adding surcharge to the head or body of a slope? (P. 530)

Back 85

The effect of surcharge (overloading) applied upslope from the line of action of the center of gravity of the sliding mass is to increase the rotational tendency of the mass. Surcharge loads introduced by humans, including mine wastes and construction fill, frequently initiate slope failures.

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Concept: How does the addition of increased pore water pressure affect slope stability? (P. 528)

Back 86

A problem encountered with reservoirs provides an interesting application of the relationship of pore pressure and mass movements. The water table in the slopes adjacent to a reservoir rises and falls to adjust to the water level in the impoundment. When the water table rises, the decrease in resisting forces is offset by the lateral support exerted by water in the reservoir on the reservoir banks. If the water level in the reservoir is rapidly lowered, perhaps in anticipation of a flood that must be contained or partially contained in the reservoir, the lateral support provided by the water is removed. The water table in the adjacent slopes is much slower to respond, and the high pore pressures now tend to cause slumping of bank material into the reservoir.

Front 87

Discussion Question: What are the specific objectives of remedial actions after a slope failure has taken place? (P. 536)

Back 87

Once a slope fails, remediation is necessary unless the area can be abandoned and all structures relocated. In addition to reconstruction of highways, buildings, etc., the slopes must be stabilized to prevent a reoccurrence of the event. The methods tend to reduce the driving forces and increase the resisting forces of the slope.
Reducing the driving forces tend to reduce the mass of material acting to cause downslope movement above a failure plane. Increasing the resisting forces of the slope tend to stabilize the slope.

Front 88

Discussion Question: How could an engineer increase the stability of a slope considered to be unsafe or on the verge of failure? (P. 536)

Read the paragraph on that page.

Back 88

..

Front 89

Concept: Memorize figure 14.2 so you can identify the five common drainage patterns and be able to list the five drainage patterns.
Pg. 546

Back 89

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Front 90

Discussion Question: Describe the ways in which sediment is transported in streams.

Back 90

*Dissolved load* is carried totally in solution by a stream.
Of the non-dissolved load of a river, the smaller particles are carried as *suspended load*. This form of transport implies that particles are prevented from settling to the bottom of the stream by the movement of the water.
The final type of load is the fraction of the total load that generally remains in contact with the bed during transportation. *Bed load* includes the particles that are too large to be transported by suspension. These particles move by rolling or sliding along the bed or by a process known as saltation, in which turbulent eddies can temporarily life a particle off the bed.