Final

Question 1

Ablation Till

Answer 1

• Till laid down by melting ice, usually ice that has become stagnant.
• combination of englacial and supraglacial flow tills
• Thick, sandy and bouldary melt-out till
• Like basal till, but fewer fines, more gravelly, more angular, less dense, no fabric.

May have some stratification or lenses of water-borne sediments.
• NOTE: tills can easily be mixed up with colluvium!

Question 2

Ablation Zone

Answer 2

*The lower part of the glacier.

*Zone of an active glacier where more snow and ice is lost in summer than is gained in winter.

• Snow melts seasonally here → net deficit of ice.

*Distinguished from the accumulation zone.

*Loss of snow and ice due to melting in temperate regions, but also evaporation, calving, wind and river erosion, and sublimation.

• Negative mass balance: continuously shrinking, but fed by flow of ice from above.

(• Equilibrium line: separates accumulation and ablation zones.)

-transfer of mass from the accumulation and ablation zones maintains a constant or equilibrium surface gradient.

Question 3

Abrasion (Aeolian)

Answer 3

• Most probable mechanisms for dust generation in deserts
• The grinding or wearing action of sand and other material carried by the wind against rock surfaces
• Limited to the ability of the wind to lift abrasive sand in saltation

Question 4

Abrasion (Glacial)

Answer 4

• Scouring of rock by glacial ice and embedded sediment (clasts)

• As clasts are move in traction, their edges and corners cut striations, while the finer abrasives polish the underlying rock surface.
• meltwater is responsible for transporting abrasive materials (along with going along with the glacier itself)
• Rates of abration may be greatest with low debris concentrations.

Rates of abration depend on frequency of contract between abrasic materials and bedrock, hardness of abrasives relative to bed, and the downward force exerted on the abrasives.

-Big angular clasts are most effective

• Rates of up to 5 mm/yr have been determined.

• Highest pressure in front of the slope, and lowest behind it.
• Cold based ice does not allow for much abrasion - and even protects the bed (because abrasion requires the presence of water) - Warm based ice is much more effective..

Question 5

Abrasion (Rock Coasts)

Answer 5

Rock fragments and sand are swept, rolled, dragged over or thrown against rock surfaces

-Cylindrical depressions (potholes) develop where large clasts are rotated by swirling water inthe surf or breaker zones.

Question 6

Accumulation Zone

Answer 6

*The upper part of an active, moving glacier.

• Positive mass balance: surplus of snow and ice here force the glacier to move downhill.
*snowfall accumulates and exceeds the losses from ablation

• Firn survives the summer.

(- Continental Glaciers grow outward from accumulation zones)

Question 7

Aeolian Erosion processes

Answer 7

Abrasion

Deflation

Question 8

Aeolian Transport

Answer 8

*** FIGURE 12.3 IN TEXT

Question 9

Aggradation

Answer 9

• To build up the floor or slope of a river by deposition. Slopes built up in this way are described as aggradational
• Increasing amounts of sediment cause single channels to widen and aggrade, promoting braiding

Question 10

Alluvial Fans

Answer 10

• Sloping, fan-shaped deposits built upon the floodplain of a larger river.
• Stream often splits into multiple distributary channels.
• Typically occur where streams leave steep mountain valleys and enter a larger, main river valley.
*upper fan is the youngest
*consists of sand and gravel
*Cone shaped,

Question 11

Alluvium

Answer 11

Fluvial sediments: Valleys often have a fill of this stuff: a combination of bar and floodplain deposits

-Sediment deposited by rivers and consisting largely of sand, silt and clay

Question 12

Alpine Erosional Landforms

Answer 12

**FIGURE 7.8 & 7.9 IN TEXT

• Cirques
• Gacial troughs
• Hanging valleys
• Truncated spurs
• Fjords
• Aretes
• Horn

Question 13

Alpine Glaciers

Answer 13

• Long and narrow mountain glaciers which fill / carve valleys or ‘troughs’.
• Begin as “pocket glaciers” in high alpine bowls.
• Flow together like streams.
• Coalesce into piedmont glaciers when they leave the mountains.

(May feed continental glaciers, if fringes are mountainous)

(landforms are similar for both alpine glaciers and ice caps/sheets, though dimensions will differ..)

PAGE 229 for picture.. coooool.

Question 14

Amplification

Answer 14

*Shaking levels at a site may be increased, or amplified, by focusing of seismic energy caused by the geometry of the sediment velocity structure, such as basin subsurface topography, or by surface topography.

*Two important local geologic factors that affect the level of shaking experienced in earthquakes are (1) the softness of the surface rocks and (2) the thickness of surface sediments.

Question 15

Anabrancing

Answer 15

• Multiple, stable, low-sinuosity channels.
• Well developed levees, many vegetated islands.
• Floodplain relatively distinct

*consists of two or more fairly deep and narrow interconnected sand or gravel channels that enclose floodplain areas
*Similar to braided rivers, except these are separated by prominant natural levees, wetlands, ponds and vetegated semi-permanent islands. Also the islands are much larger than the channels, where in braided, they are similar to the size of the channel.

Question 16

Angle of Repose (or internal friction)

Answer 16

The steepest surface gradient of loose sediment. The mass angle of repose ranges from about 32-35 degrees, generally increasing with diminishing grain size and decreasing sphericity. Individual grains, however, can have much higher angles of repose.

Question 17

Arete

Answer 17

• Sharp-crested ridges acting as the divide between two glaciated areas.

Question 18

Barchan dunes

Answer 18

• crescent-shaped features, horns point downwind.
• ~1 m to 100’s of m from horn to horn.
• unidirectional winds.
• Indicates that strong, competent, frequent winds
• form where sand supply is limited, and they are the fastest migrating form

*Little vegetation in the area

*Aeolian transport is more rapid across and around the sides of patches or mounds of sand than across the centres, where sand is the thickest.

Question 19

Barchanoid ridges

Answer 19

• Barchans frequently occur in coalesced forms called barchanoid ridges
• oriented perpendicular to the wind direction.

Question 20

Barrier islands

Answer 20

**FIGURE 14.4 IN TEXT

Coastal landscape

• Depositional landform
• vulernable to subsidence, erosion and rising sea levels

*Long narrow beach forms completely separated or detached from the mainland
-Enclose estuaries, emayments or narrow lagoons that are connected to the open sea through cannels or tidal inlets between the islands

*Some shift landward and some along the shore (due to longshore transport)

Question 21

Basal Till (lodgement till)

Answer 21

Glacial sediemtn deposit

*Till that has been carried or depoisited a the bottom of the ice

*Dense and overconsolidated, often dominantly fine-grained, and with clasts that have rounded edges and sometimes striated or faceted surfaces.
*Have distinct till fabric, sometimes with stone dipping gently upglacier, in accordance with the direction of maximum stress.

Question 22

Baymouth barriers

Answer 22

Coastal Landscape

-Depositional feature as a result of longshore drift.
*A spit that completely closes access to a bay, sealing it off from the main body of water.

*usually consist of accumulated gravel and sand carried by the current of longshore drift and deposited at a less turbulent part of the current.
*
commonly occur across artificial bay and river entrances due to the loss of kinetic energy in the current after wave refraction.

Question 23

Bedload transport

Answer 23

Fluvial sedimentary process (transport)

– Almost entirely function of flow volume, velocity and turbulence
– Sand and coarse particles roll, slide and saltate (jump) at constant rate unless obstructed
– Increase in flow strength causes entrainment and a fall in velocity causes deposition
*Much slower than the flow velocity
*Sediment becomes finer downriver because size sorting in bed load and, to a lesser extent, because of abrasion and particle breakdown. Because of this, bed load becomes increasingly secondary to suspended load down the course of the river

Question 24

Braided

Answer 24

River Channel Pattern

• Typical conditions:
o Erratic (flashy) discharge.
o Steep slope, low sinuosity.
o Relatively coarse bed material (> sand)
o High sediment load.
*Most common in high latitudes
*Very common at glacier outwash deposits

• Some characteristics:
o Multiple small, shallow channels.
o Many bars.
o Highly unstable.
*One or more channels are usually dominant in large braided rivers

Question 25

Calving

Answer 25

Where ice breaks off glaciers in big chunks

Question 26

Carbonation

Answer 26

Chemical weathering carbonates are not usually the end products of weathering, but their formation represents an important step in the breakdown of feldspars and some other minerals • Solution of minerals in carbonic acid (water + CO2). \*CO2 from atmosphere, decaying organic matter. * Example: solution of calcite. * Formation of carbonic acid: H2O + CO2 → H2CO3 * Solution of calcite: CaCO3 + H2CO3 → Ca2+ + 2HCO3- • Prevalent in limestone bedrock (almost pure CaCO3).

Question 27

Cascade Pool

Answer 27

Small Channel ## Footnote • Low discharge (typically 3rd-order or less). • Steep (S between 2º and 20º) \*Narrow o Usually found in headwaters of a watershed. • Usually coarse bed material. • Common channel patterns: o Both low sinuosity. o Low sediment transport. \*closely spaced pools -continuous, turbulent flow

Question 28

Celerity

Answer 28

(Swiftness of movement) (wave property) (c)=lambda/T

Question 29

Channel Bed Characteristics

Answer 29

\*many local variables o Grain size decreases and clast rounding increases progressively downstream o Bedforms include pool-riffles, potholes, bars, dunes, ripples, etc. armoured beds o Large woody debris important Drainage Patterns controlled by: o Bedrock structure (e.g. joints, faults) o Bedrock lithology o Sediment grain size

Question 30

Channel Gradation

Answer 30

o Most of BC’s river valleys have been through a cycle of channel gradation since the end of last Ice Age: i. Aggradation of glaciofluvial sediment. ii. Degradation as sediment supply dwindles. o This has produced multiple terraces in many valleys. Graded streams Aggradation Degradation

Question 31

Channel Sands

Answer 31

Sand deposited in a stream bed or other channel that has been eroded

Question 32

Chemical Weathering

Answer 32

Oxidation Carbonation Solution (leaching) Hydrolysis

Question 33

Chevron Crevasse

Answer 33

- develop because of drag with the valley walls, open at right angles to the max tension. Run 45 degrees downstream to the valley sides.

Question 34

Cirques

Answer 34

* High alpine bowl where glaciers begin. * Often occupied by small lakes called tarns.

Question 35

Coastal foredunes

Answer 35

\*Wind flow accelerates around hard objects, causing sand grains to bounce further and higher. • Wind direction can vary as flows from a variety of incident angles are steered shoreward by changing roughness and surface slope at the back of a beach \*Saltation across the upper portion of many beaches can be enhanced by the presence of shells etc \*Dunes begin to develop above the high tidal level, where the wind is deflected around vegetation and other obstacles \*Vegetation grows (light), and encourages more accumulation of sand * Along the coast, there is typically a foredune complex (linear, shore-parallel, vegetated dunes backing a sandy beach) * Blowouts occur when strong onshore winds erode a gap in a coastal foredune, sweeping sand from the beach and dune inland * These typically grade into parabolic dune * Coastal dunes buffer against storm surges & sea-level rise

Question 36

Cohesion

Answer 36

A force that is involved in slope stability

Question 37

Col

Answer 37

Low pass in arete

Question 38

Colluvium

Answer 38

Sediment deposited by mass wasting, other hillslope processes. • unstratified or weakly stratified. \*Loose, unsorted, weathered Map Symbol: C _Active_ status of formative process Can easily be mixed up with till.

Question 39

Continental Erosional Landorms

Answer 39

\*\*FIGURE 7.7 Whalebacks Rock Drumlins Mega-Grooves Rock Basins

Question 40

Continental Glaciers

Answer 40

* Dome shaped glacier which buries the landscape. * Grow outward from central accumulation zone. * May be fed by high alpine glaciers, or have alpine ‘outlet glaciers’ if fringes are mountainous. * May spread onto ocean → ice shelves. * Ice caps \< 50 000 km2. * e.g. Pemberton Icefield, Columbia Icefield. * Ice sheets \> 50 000 km2. * e.g. Antarctica, Greenland “Ice Cap.”

Question 41

Convergent plate

Answer 41

Where tectonic plates collide → intense geological activity. • Subduction of one plate beneath another. • Earthquakes. • Chain of volcanoes. • Folding and faulting. • Joining of continents.

Question 42

Coppice dunes

Answer 42

* Coppice dunes are vegetated sand mounds that are commonly scattered throughout sand plains in semiarid regions where shrubs and blowing sand are abundant * They can be incipient forms of parabolic dunes because the vegetation anchors them * Common in coastal areas

Question 43

Coulomb Equation

Answer 43

S = c + (σ – μ) tanΦ ## Footnote S = shear strength c = cohesion σ = effective normal stress (=mg cosβ) μ = pore pressure due to water Φ = angle of internal friction (angle of respose)

Question 44

Crag and Tails

Answer 44

Form from ice push, abrasion and plucking can be considered a special type of drumlin in which a tail of sediment extends downstream from a projecting rock knob. \*Cavaties on the lee side of the rock obstructions can fill with sediment falling from the roof or washed in by meltwate

Question 45

Creep

Answer 45

• Slow, shallow downslope movement of soil or rock debris. * Rates ~ 0.1 and 15 mm/year. * Fastest at surface. * Main soil creep mechanisms: * Freezing and thawing. * Wetting and drying. * Solifluction / gelifluction. * Creep depends on water content, grain size, and slope angle. * Typical indicators: uphill-bent trees, tilted poles, folded strata, small terraces. \*Pariglacial slope processes: Gelifluction and frost creep.. (solifluction..)

Question 46

Crevasses

Answer 46

* Glacier slows at rock obstacles, surges over steps. * Crevasses are basically normal faults in the ice where under tension. * May form icefalls in very steep places. 3 simple types.. Chevron crevasse - drag with valley walls - 45 degrees Splaying crevasse - meet with valley walls at less than 45 degrees Transverse crevasse - right angles..

Question 47

Cross-bedding

Answer 47

Fluvial sediments - small and larger scale structures.. May show flow direction. -ripple, dunes bar architecture \*Consists of foreset beds that are steeply inclined to the main bedding plane. \*Most frequent in sandy sediments in fluvial, coastal and aeloian environments, as erosion occurs on the upstream side and deposition at the angle of repose on the downstream side of migrating ripples, sand waves and sand dunes. \*Fluctuation in discharge and velocity cause bed erosion and the formation of depressions that are later filled with sediment Trough cross-bedding - produced by bedforms with curved or irregular crests Planar cross-bedding - bedforms with linear or straight crests

Question 48

Cutbank

Answer 48

Erosional landform (sediment) - found in abundance along mature or meandering streams - located on the outside of a stream bend, known as a meander, opposite the slip-off slope on the inside of the bend. - shaped much like a small cliff, and are formed by the erosion of soil as the stream collides with the river bank. - Often erosion proceeds to turn the meandering river into an oxbow lake

Question 49

Debris Avalanche

Answer 49

- Long-runout rockslides - the debris of rock fragments assumes a transition streaming or flowing motion followed by falls and flows (cushion of compressed air, dense cloud of dust, vapourized intersitial water, or wet mud) - can have rates of more than 300 km/hr, and distances of 5-20 times the height of the vertical descent - In canada - tend to occur in well-jointed, steep rock dippings at angles 25-40 degrees. - triggered by heavy precipitation, frost action or seizmic event - Direction of slip movement is almost always normal to the anticlines, synclines, thrust faults etc. • Snow avalanches sometimes included here…

Question 50

Debris Flow

Answer 50

• Rapid flow of muddy water with large amount of coarse material (e.g. boulders, trees, cars). • Less water than mud flow. • Poorly sorted. \*In valleys and mountainslopes \*From heavy seasonal rainfall or snowmelt \*Travel considerable distances \*may form ridges or levees along the sides of the valleys when they decelerate. (large cones or fans at the front of the flow)

Question 51

Deglaciation

Answer 51

\*glacialmarine -\> non-glacial sediments • Beware of unconformities: erosion boundaries between strata → loss of information. • Erosion may go right to bedrock. \*Movement of the glacier ceases when there is no longer an accumulation zone. \*Deglaciation over large areas was accomplished by ice thinning and ice disintegration rather than the steady retreat of the ice margins.. \*Dominant features are a vaiety of ridges and plateaus • These deposits and other landforms are the clues with which our glacial history was reconstructed!

Question 52

Degradation

Answer 52

Lowering of the land surface by erosion In River.. =excessive erosion of the river bed (downcutting). o Channel is locally lowered → slope decrease. o Possible causes: • Decrease in sediment load (e.g. end of glacial stage). • Increase in flow (e.g. inter-basin flow diversion). • Fall in base level (e.g. tectonic uplift).

Question 53

Delta

Answer 53

Glaciolacustrine depositional landform * Fan-shaped deposits where streams enter proglacial lakes. * May be abnormally large due to the enormous load of sediment. • Built where a river enters standing water (lake or ocean). • Flatter, finer grained than alluvial fans. • Exact shape depends on coastal processes. \*River drops load as enters a body of standing water (sea or lake) \*Fail to develop in areas with strong waves, currents or tides, or where the river carrier little sediment

Question 54

Depositional Aeolian features

Answer 54

Ripples Dunes Loess deposits

Question 55

Determinants of Channel Form

Answer 55

Discharge Sediment Load Sediment calibre Slope

Question 56

Diamiction

Answer 56

\*Any poorly sorted mixture of mud, sand and rock fragments \*Tills are glacial diamictons

Question 57

discharge

Answer 57

-Volume rate in water flow - includes loads that are transported in the volume (Q) - the most important variable in determining channel morphology. o Related to climate, position in watershed. o Amount determines channel size; timing is important in determining style of channel. * Q is the volume of water per unit time passing through a cross-section of a stream. * Q = Av * A = cross-sectional area (Wd), v = mean velocity. * Or Q = w d v • Maximum velocity occurs almost at the top / centre (or outside of a bend). * Temporal: varies in response to changing precipitation, snowmelt inputs (seasonal, storm-scale). * Discharge Hydrographs show changes in Q with time.

Question 58

Dissociation

Answer 58

In chemical weathering (solution - leaching) ## Footnote The separation of cations and anions and their dispersion in water. * Dissociation of minerals in water. * Ions added to groundwater, surface water. * E.g. basaltic rocks in Hawaii → karst-like features - mostly salts, gypsum, carbonate esp.

Question 59

Dissolved Load

Answer 59

Sediment transport.. ## Footnote • Dissolved (solutional) load – solute concentration is often estimated from the electrical conductivity of the water (doesn’t include dissolved silica, important in tropical rivers) \*Solutional load concentrations usually decrease with increasing discharge (high discharge also has less opportunity to pickup solute) \*During periods of low flow, concentrations increase as a result of evapotranspirational losses from chanls and the supply of groundwater \*Higher solutional load over limestone, dolomites or evaporites and low in areas of shield bedrock.

Question 60

Distributary Channel

Answer 60

A river channel usually deltaic, that splits off from the main channel and does not rejoin it

Question 61

Divergent Plate

Answer 61

Divergent margins: ## Footnote o The ocean bottom is a vast lava plateau. o Lava plateaux may also form when large cracks in the crust form in non-divergent settings. \*Large ridges or mountainchains develop beneath the oceans along the divergent margins \*New crust is created from volcanic material welling up into the gap

Question 62

Drumlins

Answer 62

Continental Erosional Landform (Ice contact) Rock drumlin: • Like whalebacks, but asymmetrical. • Steeper end up-glacier • Dimensions: height up to 50 m, length up to several km. * Drumlins * Streamlined hills of till up to 60 m high. * Usually teardrop-shaped (steep side up-glacier). * Usually occur in groups (swarms or fields). Drumlins formed under ice sheets are often distributed in bands that are paralell or perpindicular to the direction of ice movement. Direction of ice flow should not be based on a single drumlin, as a small proportion of the forms in drumlin fields have reversed profile shapes in relation to ice flow.

Question 63

Dunes (Aeloian)

Answer 63

Aeolian landscape and landforms ## Footnote Hills of windblown sand Variable types of dune depended on sand availability, grain size and distribution, wind energy, vegetation etc. Depositional form: Barchans Barchanoid ridges Transverse dunes Parabolic dunes Coppice dunes Coastal dunes Longitudinal dunes Star dunes Loess deposits

Question 64

Dunes (River)

Answer 64

Larger features, ranging up to a meter or more in height and spacing \*Rarely found in rivers with gravel beds \*Eddies form on lee side of Dunes \*Dunes advance downstream At Higher velocities, antidunes develop, with a great increase in the amount of sediment moving along the bed. \*Antidunes move upstream because sediment is lost to saltation and suspension on the downstream side faster than it can be replaced

Question 65

Earth flow

Answer 65

* Moderately rapid downslope movement of saturated soil / sediment. (Between creep and mudflow) * Very common in old marine deposits (clays liquefy). \*Often develop from spreading of slumps and are also common where there are moderate gradients and clay or clay-bearing rocks.

Question 66

Convergent plate

Answer 66

Where tectonic plates collide → intense geological activity. • Subduction of one plate beneath another. • Earthquakes. • Chain of volcanoes. • Folding and faulting. • Joining of continents.

Question 67

Effective normal stress

Answer 67

Effective Stress is a force that keeps a collection of particles rigid. Usually this applies to sand, soil or gravel. ex. a pile of sand keeps from spreading out like a liquid because the weight of the sand keeps the grains stuck together in their current arrangement, mostly out of static friction. This weight and pressure is the effective stress.

Question 68

End moraines

Answer 68

produced at front of actively flowing glacier. • Terminal moraines: mark the farthest advance. • Recessional moraines: mark temporary halts or re-advances of ice in a period of general recession. \*Made in front of an active or inactive glacier. \*consist of debris that was carried mainly at the bottom or on the top of the ice. \*Another type was formed where frozen sediments and bedrock were pushed and thrust upward into faulted blocks by the advancing ice sheet.

Question 69

Englacial Till

Answer 69

-Located or occurring within a glacier, as certain meltwater streams, till deposits, and moraines

Question 70

Equilibrium Line

Answer 70

separates accumulation and ablation zones. • ~ the firn line. • In reality, this is more like a zone. \*At the ELA - the snow and ice added in a balance year is exactly equal to the amount that is lost. \*Balance year is generally taken to be the time between two successive annual minimums in the mass of the glacier)

Question 71

Erosion limited

Answer 71

A part of hillslope erosion \*weathering / sedimentation is faster. * Unconsolidated material accumulates, covers bedrock. * Typical of gentle-moderate slopes.

Question 72

Erosional Landforms (Glaciers) | (Mechanisms and small features)

Answer 72

Mechanisms: Ice push, Abrasion and Plucking Small Features: Polish, Striations, Grooves, Crag and Tails, Roch Moutonnees

Question 73

Eskers

Answer 73

• Winding ridges produces by streams in tunnels beneath or upon the ice. (Glaciofluvial material) \*Mostly sand - but with gravel and cobble materials also \*Usually found relatively close to source - ~15kms -Glaciofluvial deposits: like braided river, but maybe thicker - often disturbed due to loss of ice support (eskers)

Question 74

Eustatic

Answer 74

\*\*SEE TEXT FIGURE 13.11 o Glaciation → water stored in glaciers → sea level fall. o Deglaciation → meltwater in oceans → sea level rise. * Late Cenozoic: * Sea level dropped eustatically by at least 100 m. A global change of sea level resulting from a rise or fall of the ocean level rather than of a change in the level of the land. \*Eustatic changes in sea level in the Pleistocene were mainly cause by the growth and decay of ice sheets, but the changes in the volume of the ocean basins due to tectonics and sedimetation were important in the Tertiary.

Question 75

Exfoliation

Answer 75

* Rocks tend to split into sheets parallel to the topography. * e.g. granitic exfoliation domes (Yosemite) * Produces ‘dilation joints’. * Note: small-medium scale peeling off of rock slabs = ‘spalling’. * Freezing water or chemical precipitation in cracks can assist exfoliation. * Compression can also help.

Question 76

Factorof Safety

Answer 76

(Fs) is used to define slope stability. • Fs = S / τ. • Fs \> 1 → stable slope. • Fs \< 1 → unstable slope. • Some slopes may exist temporarily in an unstable condition. term describing the structural capacity of a system beyond the expected loads or actual loads. Essentially, how much stronger the system is than it usually needs to be for an intended load.

Question 77

Faulting

Answer 77

fracturing of brittle rock from unequal stress; usually involves displacement along fault plane (plane of fracture). • Sudden slippage along fault plane results in earthquakes • 4 major types of faults: 1. Normal: relative vertical movement of crustal blocks along steep fault plane. Associated with rifting. 2. Reverse: associated with compressional forces. One block riding up over the other, producing very steep fault scarps. 3. Overthrust: akin to a low-angle reverse fault, one block rides up on top of the other along a near-horizontal fault plane. • E.g. Canadian Rockies → 100s of km. 4. Transform (transcurrent or strike-slip): relative horizontal movement of crustal blocks along nearly vertical fault plane. • E.g. San Andreas Fault

Question 78

Fetch

Answer 78

2. Fetch (area of water over which wind blows). Wave energy is dependent on fetch, among other variables

Question 79

Fining upward sequence

Answer 79

grain size is decreasing upward in the sandstone core/rock/outcrop. A good example of a fining-upward succession is a river point bar Point bars get their unique shapes because of the way water flows through curving channels like bends in a river. As the water enters the bend of the river the flow spins in a spiral. The flow is strongest on the outside of the bend causing erosion of the outer bank. As the water flows away from the outer bank and rises up the slope of the inner bank, or point bar, it loses some of its energy and begins to deposit sediments eroded from the outer bank. First the coarse grains are deposited near the base of the point bar and then the finer grains as the water flows towards the top of the point bar.

Question 80

Firn Line

Answer 80

\*firn is partially compacted snow or ice that is at an intermediate stage between snow and glacial ice the zone of a glacier between the lower region of solid ice and the upper region, above which ablation occurs

Question 81

Fjords

Answer 81

* Troughs invaded by rising ocean water. * Very common on the BC coast, e.g. Alberni Inlet, Howe Sound.

Question 82

Flashy Discharge

Answer 82

Flashy discharge is a type of flood characterized by short lag times between rainfalls and the rapid rise and fall of floodwater because of urbanization. Flash discharge is of higher magnitude (higher peak of discharge) because water is discharged in a shorter time period.

Question 83

Flows

Answer 83

• Movements of liquefied material → lots of water required. ## Footnote * Failure usually begins on a plane. * Often rotational. • Debris is deposited in a lobe. * Flows occur when: * Large amounts of weathered material are available. * Large amounts of water. * Steep slope (if only locally). Three principal types: Mud flow Earth flow Debris flow

Question 84

Folding

Answer 84

* Initial, plastic deformation of rocks under compressional stress (convergent margins). * Most common / evident in sedimentary rocks. * Anticlines (ridges) and synclines (troughs or valleys).

Question 85

Foreset beds

Answer 85

A foreset bed is one of the main parts of a river delta. It is the inclined part of a delta that is found at the end of the stream channel as the delta sediment is deposited along the arcuate delta front. As the sediments are deposited on a sloping surface the resulting bedding is not horizontal, but dips in the direction of current flow toward deeper water. A cross-section of a delta shows the cross bedding in the direction of stream flow into the still water. The foreset bed is formed when a stream carrying sediment meets still water. When the stream meets the still water, the velocity of the water is decreased enough so that the larger sediment particles can no longer be carried and are therefore deposited. The deposited sediment builds up over time, and a delta is formed.

Question 86

Fraser Glaciation

Answer 86

* Peak of Fraser Glaciation = Vashon Stade (~ 14,500 years BP). * Alpine glaciers expand, coalesce into major valley and piedmont glaciers. * Large ice sheet advances down Strait of Georgia past Seattle. * Overrides Vancouver Island, fills Strait of Juan de Fuca, may extend to continental shelf off west coast. Associated Sea leve changes... Eustatic and Isostatic

Question 87

Friction

Answer 87

Angle of internal friction/repose - Texture - Angularity of sediment - Compaction - Involved in sediment erosion

Question 88

Frost action

Answer 88

* Repeated growth and melting of ice crystals in the pore spaces of rock. * Liquid water seeps into joints. * Expands 9% upon freezing → powerful force (e.g. Quebec highways). * Factors in effectiveness: * Ample water supply is critical. * Frequency, speed and duration of freeze/thaw cycles may be important. • Actual mechanism may be related to crystal growth and/or water pressure.

Question 89

Gelifluction

Answer 89

Soil flow that refers to the movement of freeze-thaw surface material over permanently, seasonally or even diurnally frozen ground. \*Gelifluction usually periglacial land (sides of glaciers)

Question 90

Geomorphic processes

Answer 90

Terrain symbol mapping.. • Natural mechanisms of weathering, erosion and deposition that result in the modification of the surficial materials and landforms at the earth’s surface. mostly assumed to be active

Question 91

Glacial troughs

Answer 91

* Glacier-carved valley. * U-shaped cross-section . * Typically straighter than unglaciated valleys

Question 92

Glacier mechanisms

Answer 92

ice push abrasion plucking

Question 93

Glaciers

Answer 93

\*\*FIGURE 6.3 & 6.6 IN TEXT * A glacier is a moving mass of ice that has its genesis on land. * Glaciers are powerful geomorphic agents: * Friction caused by moving ice → erosional landforms * Deposition of eroded sediment → depositional landforms Formation overview... * Glaciers may form in any area with a year-to-year surplus of snow. * Successive layers of snow are slowly compacted * Snow crystals gradually become more dense, bonded with increasing burial depth and age (becoming ‘firn’). * Firn crystals melt / squeeze together into glacial ice. * Gravity slowly deforms and moves this mass of ice. * Weight of glacier forces ice to deform in a plastic way → flows!

Question 94

Glaciofluvial

Answer 94

Material Name - Fg (inactive) * Produced by meltwater streams around glaciers. * Deposits = ‘outwash.’ - sand and gravel Deposits: Like braided river, but maybe thicker. Often disturbed due to loss of ice support (eskers, kames). Outwash Plaines Eskers Kames

Question 95

Glaciolacustrine

Answer 95

* Proglacial lakes often formed by the damming of a valley by a moraine or ice. * Striking turquoise colour due to glacial rock flour in suspension. Material name: Lg (inactive) deposits: Fine-grained (clayey to sandy muds), finely stratified, unconsolidated, often including larger ‘dropstones’. Deltas Kames deltas Kettles

Question 96

Glaciomarine

Answer 96

deposits: As glacial lacustrine, but with more clay, marine fossils. Material name: Wg (inactive) Associated with meltwater streams in contact with the sea.

Question 97

Graded Stream

Answer 97

o Over a period of years, slope is delicately adjusted to provide, with available discharge and prevailing channel characteristics, just the velocity required for the transportation of the sediment load supplied from the drainage basin (Mackin, 1948). but with no extra energy for erosion\* o i.e. stream has equilibrium slope

Question 98

Gravel

Answer 98

A mixture of two or more size ranges of rounded particles greater than 2 mm in size (e.g., a mixture of boulders, cobbles and pebbles); may include interstitial sand. Material: g

Question 99

Gravity

Answer 99

Effects Q, surface runoff, slope stability, mass wasting ## Footnote \*Helps to drive geomorphological agents on the Earth, including mass movements, rivers, glaciers, and tides. \*Internally, it is fundamental to the occurane and operation of isostasy

Question 100

Ground Moraine

Answer 100

\*plastered over the ground in the path of the glacier. \*consists of an irregular blanket of till deposited under a glacier. \*Composed mainly of clay and sand, it is the most widespread deposit of continental glaciers. \*Although seldom more than 5 metres (15 feet) thick, it may attain a thickness of 20 m.

Question 101

Gully Erosion

Answer 101

Material symbol: V - (active) * Rills may join to form gullies: deeper, V-shaped channels carved by ephemeral streams during advanced stages of accelerated slope erosion. * Can be several metres deep / wide. * Develop in all climates, but especially prominent in arid areas (badlands) and cleared land (e.g. cut blocks). • Management Implications… * Erosion may increase with more surface runoff or a weaker slope. * Possible negative consequences… * Loss of topsoil → loss of soil fertility. * Increased sediment load in streams. * More intense flooding. * Possible causes: * More intense runoff. * Land clearing, roads. * Less permeable soil. * Land clearing, farm equipment, livestock. * Steeper slopes. * Road cuts.

Question 102

Hanging Valleys

Answer 102

* Truncated where they meet a larger glacial trough. * Often the sites of waterfalls.

Question 103

Hillslope Erosion

Answer 103

Affected by gravity and surface runoff - depth/velocity of water vs material strength (factors include texture, cohesion, vegetation) Slopes may be Weathering limited or Erosion limited Sheet Erosion Rain Splash Erosion Channel Initiation (Rills and Gullies)

Question 104

Horn

Answer 104

* Jagged peak that has survived the glacial erosion all around it. * Nunatak = a horn protruding from an ice field.

Question 105

Hydrolysis

Answer 105

A part of chemical weathering ## Footnote * Water is the most important agent of weathering. * Important: need water flow so that solution and rock don’t reach equilibrium! * Air helps too. * Variable effects of pH. • Breakdown of water into H+ and OH- ions. * H+ ions replace metal cations in rock. * Freed cations combine with OH- ions → form soluble oxides. * Accelerated if there is CO2 in the water. * Significance: weathering of silicates. * This is the dominant process in igneous rocks. • E.g. weathering of a ferro-magnesian mineral: Hornblende + H2O + CO2 → Clay + Calcite + Silica + Fe Oxide + OH-

Question 105

Ice Sheets

Answer 105

Large, dome shaped, subcontinental - to continental glacier * Ice sheets \> 50 000 km2. * e.g. Antarctica, Greenland “Ice Cap.” • Major Wisconsin ice sheets in Canada: 1. Laurentide Ice Sheet: • Centred on Hudson’s Bay. • Covered most of Canada from the Rockies to Baffin Island to NF. • Up to 3 km thick! → major isostatic effects around Hudson’s Bay. 2. Cordilleran Ice Sheet: • Complex of coalescent alpine glaciers in the western mountain belts. • Flowed together as piedmont glaciers at base of mountains. • Covered all of BC, extended out over continental shelf.

Question 105

Ice push

Answer 105

• Glacier pushes loose rock debris like a bulldozer.

Question 105

Hot spots

Answer 105

Create Shield volcanoes and Intrustions Shield Volcanoes: form when a plate passes over a stationary mantle plume. Usually built almost entirely of fluid lava flows Intrusions: may form if magma cools before reaching surface. - igneous rock that was pushed into cavities of rock during its magma form. • May be exposed by erosion later.

Question 105

Hydrographs

Answer 105

\*\*FIGURE 10.5 & 10.6 IN TEXT Plots of discharge against time for a given rainstorm event will usually produce a right-skewed curve, with a steeply increasing limb, a peak, and a prolonged recession or falling limb \*The rising limb is largely the result of the rapid increase in discharge from direct runoff, whereas the falling limb reflects the gradual depletion of water stored in the soil and rocks of the drainage basin. When rain first begins to fall over a drainage basin, some falls directly into river channels, producing an immediate increase in discharge. Saturation surface flow from floodplains and the base of slopes makes the greated contribution to direct runoff in humid regions It begins soon after the onset of rain, and as the water table rises during prolonged rainfall, the saturated size of the contributing area seepage into river channels from the banks and rapid delivery of water through root channels and pipes can be significant Baseflow (infiltrated water released more slowly from the ground) is respoinsbile for river flow during dry periods and is therefore an important consideration when considering lags between rainfall and flow. In urbanized areas, the runoff is very high, and the rainfall and runoff go hand in hand, while there is a lag in a wooded area. 3 kinds of hydrographs.. Stage hydrographs, discharge hydrographs, flow-duration hydrographs

Question 106

Intrusions

Answer 106

* Intrusions may form if magma cools before reaching surface. * May be exposed by erosion later. A body consisting of igneous rocks that in a molten state, were forced into the cavities in pre-existing rock strata.

Question 106

Intermediate Channels

Answer 106

• Higher discharge (order roughly 3-4). • Slope generally 1º to 2º. o Stone nets or bars more prominent. o Fallen trees or log jams (LWD) often important in determining morphology. • So size limit of roughly W = 20-30 m. • Riffle-pool is the usual channel pattern. o Low-moderate sinuosity. o Moderate sediment transport.

Question 107

Isostatic

Answer 107

\*\*SEE TEXT FIGURE 13.11 A state of balance that is maintained in the crust of the Earth. Distrubrance of this balance causes isostaic movements, which act to restore the balance. These movements, which act to restore the balance. These movements may involve uplft of the land to comepesate for erosion, or depression of the land to accomodate the weight of accumulated sediment. Glacio-isostasy involves the depression of the land owing to the weight of a large body of ice, and uplift or rebound as a result of the disintegration or retreat of the ice. Sea level changes.. o Glaciation → isostatic depression of crust into mantle → sea level rise. o Deglaciation → isostatic rebound → sea level fall. * Late Cenozoic: * Land was isostatically depressed even more in places (variable).

Question 107

Kame Deltas

Answer 107

• Deposited against ice in proglacial lakes. \*Glacial landform made by a stream flowing through and around glacial ice and depositing material as a kame(stratified sequence of sediments) upon entering a lake or pond at the end or terminus of the glacier, thus "in front" of it, a proglacial lake. \*It is distinctive because it has been sorted by the action of the stream. This sorting is responsible for the stratified layers of silt, sand and gravel at the ice margin which create the delta. This landform may often be observed after the glacier has melted and the delta is visible. \*Often upon melting of the glacier the edges of the delta may subside as ice under it melts and glacial till may be deposited in the lateral or side area also as material is deposited from the melting glacier.

Question 108

Kames

Answer 108

* Isolated hills of glaciofluvial sediment originally deposited in depressions in the ice. * If between ice and valley wall, form is called a kame terrace. * Often unstable after ice support is removed.

Question 109

Kettles

Answer 109

* Depressions produced by melting blocks of ice. * Ice block was buried in till and then melted. * Usually occupied by a lake.

Question 109

Lacustrine Terrace

Answer 109

\*A lake errace represents the former shoreline of either a nonglacial, glacial, or proglacial lake. \*As in case of marine terraces, a lake terrace can be formed by either the abrasion or erosion of materials comprising the shoreline, the accumulations of sediments in the shallow-water to slightly emerged environments, or some combination of these.

Question 110

Lagoons

Answer 110

Coastal lagoons form along gently sloping coasts where barrier islands or reefs can develop off-shore, and the sea-level is rising relative to the land along the shore (either because of an intrinsic rise in sea-level, or subsidence of the land along the coast). Coastal lagoons do not form along steep or rocky coasts, or if the range of tides is more than 4 metres (13 ft). Due to the gentle slope of the coast, coastal lagoons are shallow. They are sensitive to changes in sea level. A relative drop in sea level may leave a lagoon largely dry, while a rise in sea level may let the sea breach or destroy barrier islands, and leave reefs too deep under water to protect the lagoon. Nybakken describes coastal lagoons and barrier islands as a "coupled system". Coastal lagoons are young and dynamic, and may be short-lived in geological terms. Coastal lagoons are common, occurring along nearly 15 percent of the world's shorelines. In the United States, lagoons are found along more than 75 percent of the eastern and Gulf coasts.[3][4] ## Footnote - usually connected to the open ocean by inlets between barrier islands. - The number and size of the inlets, precipitation, evaporation, and inflow of fresh water all affect the nature of the lagoon. - Lagoons with little or no interchange with the open ocean, little or no inflow of fresh water, and high evaporation rates, may become highly saline. - Lagoons with no connection to the open ocean and significant inflow of fresh water, may be entirely fresh. - On the other hand, lagoons with many wide inlets, have strong tidal currents and mixing. - Coastal lagoons tend to accumulate sediments from inflowing rivers, from runoff from the shores of the lagoon, and from sediment carried into the lagoon through inlets by the tide. - Large quantities of sediment may be occasionally be deposited in a lagoon when storm waves overwash barrier islands. Mangroves and marsh plants can facilitate the accumulation of sediment in a lagoon. Benthic organisms may stabilize or destabilize sediments.

Question 111

Lahars

Answer 111

volcanic mudflows initiated by rapid melting of snow and ice. • e.g. Nevado del Ruiz, Colombia, 1985 → lahar 40 m high wiped out town of Armero, killed 23,000 people. • Danger from Mount Rainier.

Question 111

Landslides

Answer 111

\*Landslide” is a generic term that may refer to many types of mass movement. * Sliding of large masses of rock and / or sediment. * Variable speed. * Failure generally on a distinct plane. * Usually a pre-existing weakness in the material. * e.g. cracks in clay, joints in bedrock, contact between sediment layers. * Opening for water seepage, less friction. * Translational or rotational. \*There is growing recognition that landslides and other mass movements also act as a primary control on the development, incision and sediment discharge characteristics of river drainage basins

Question 113

Large Channels

Answer 113

* Higher discharge still (getting into wide valleys). * Gradient usually \< 1º.

Question 114

Lateral Moraines

Answer 114

near the side margin of a valley glacier. ## Footnote \*Lateral moraines are parallel ridges of debris deposited along the sides of a glacier. \*The unconsolidated debris can be deposited on top of the glacier by frost shattering of the valley walls and/or from tributary streams flowing into the valley. \*The till is carried along the glacial margin until the glacier melts. \*Because lateral moraines are deposited on top of the glacier, they do not experience the postglacial erosion of the valley floor and therefore, as the glacier melts, lateral moraines are usually preserved as high ridges.

Question 115

Lava Plateau

Answer 115

Ocean bottom is a vast lava plateau at divergent margins -May also form when large cracks in crust form in non-divergent settings \*Basic lava produce very flat plateaus when in enormous quantities

Question 116

Levee

Answer 116

- elongated naturally occurring ridge or artificially constructed fill or wall - regulates water levels - often parallel to the course of a river in its floodplain or along low-lying coastlines. \*banks act as natural levees as well - but usually can't withstand the periodic major flooding

Question 116

Liquefaction

Answer 116

Soil liquefaction describes a phenomenon whereby a saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress, usually earthquake shaking or other sudden change in stress condition, causing it to behave like a liquid. The phenomenon is most often observed in saturated, loose (low density or uncompacted), sandy soils. This is because a loose sand has a tendency to compress when a load is applied; dense sands by contrast tend to expand in volume or 'dilate'. If the soil is saturated by water, a condition that often exists when the soil is below the ground water table or sea level, then water fills the gaps between soil grains ('pore spaces'). In response to the soil compressing, this water increases in pressure and attempts to flow out from the soil to zones of low pressure (usually upward towards the ground surface). However, if the loading is rapidly applied and large enough, or is repeated many times (e.g. earthquake shaking, storm wave loading) such that it does not flow out in time before the next cycle of load is applied, the water pressures may build to an extent where they exceed the contact stresses between the grains of soil that keep them in contact with each other. These contacts between grains are the means by which the weight from buildings and overlying soil layers are transferred from the ground surface to layers of soil or rock at greater depths. This loss of soil structure causes it to lose all of its strength (the ability to transfer shear stress) and it may be observed to flow like a liquid (hence 'liquefaction').

Question 117

Lithosphere

Answer 117

* Earth’s crust and uppermost mantle are made of solid rock. * This is the lithosphere (60-150 km thick). * It is not a solid shell, but broken into chunks called tectonic plates. * Oceanic vs. continental. * Tectonic plates slowly move around due to convection of lower mantle rocks. * Plate tectonics provides a unifying theory for crust formation, continental drift, earthquakes, volcanoes, etc.

Question 118

Loess Deposits

Answer 118

* windblown silts – cover large parts of the globe * during the deglaciation, large volumes of wind-blown silt or loess gets blown onto the unglaciated landscape * low latitude deserts also are a major source of global loess much of which gets deposited widely in the oceans * Loess often makes up a significant component of the B-horizon and is considered a dilutant to the native weather bedrock regolith.

Question 119

Longitudinal (linear) dunes

Answer 119

* Linear dunes are straight or irregularly sinuous, elongate sand ridges * They are aligned parallel to the forming wind and are often wider and steeper at the upwind side, gradually tapering until they merge with the desert surface. * often wider and steeper at the upwind side, gradually tapering * Curving linear dunes sometimes called ‘seif dunes’ * Form in unvegetated areas, often on bedrock. * Occur in warm deserts * Wind regimes responsible for linear dunes are usually more directionally variable than those associated with barchans or parabolic dunes

Question 119

Longshore bar

Answer 119

A ridge of sand, gravel, or mud built on the seashore by waves and currents, generally parallel to the shore and submerged by high tides. Also known as offshore bar. ## Footnote Visible at low tide as a sand bar, or a ridge of beach sediment sharing the general contour of the shoreline itself, a longshore bar is actually a feature sculpted by the push and pull of years of waves. It only seems to share the general contour of the shoreline because the break point of the waves (a point determined by depth) tends to be equidistant from shore—which itself has of course been rounded off or leveled by waves—lending any bar that shares its contour a generally level, or straight, appearance. However, this is just a function of the break point: the bottom current necessary to feed the shoreward current of a wave pulls silt in with it, then, the moment the wave breaks, deposits it, in the same place, time after time. That deposit—that steady accretion of silt—is the longshore bar. Due to the redistribution of silt, there will often be a trough between the longshore bar and the beach itself. Seaward of the longshore bar are other longshore bars at the break point of larger waves.

Question 120

Longshore drift

Answer 120

\*\*FIGURE 13.4 IN TEXT * Sideways = longshore or littoral. * This occurs because waves rarely arrive perfectly normal to shoreline. * Often there are prevailing longshore currents in an area. * May vary seasonally (e.g. Ross Bay). Varying texture along beaches

Question 121

Magnitude-Frequency analysis

Answer 121

\*\*FIGURE 2.1 IN TEXT Discharge frequency-magnitude relationships play an important role in determining how river systems operate and evolve and tey are a basic tool for river mgmt and floodplain planning For stations with long records, the relationship can be determined by considering the highest peak discharge that occurs each year, which is called a flood irrespective of whether it actually causes any flooding: this is called annual series. Alternatively, instead of only the peak discharge for each year, each discharge above some predtermined magnitude may be plotted. The floods are then listed in a descending order of magnitude and given a ranking number, with the largest being rank 1.

Question 122

Meandering

Answer 122

\*\*FIGURE 11.10 IN TEXT Symbol: M • Typical conditions: o Predictable discharge. o Low-moderate slope, moderate-high sinuosity. o Sediment calibre up to sand or fine gravel. • Some characteristics: o One main channel. o Classic cutbank / point bar / pool / riffle sequences.

Question 122

Medial Moraine

Answer 122

between two coalescing glaciers. Often extend downstream on the ice surface from the point where two lateral moraines join at the spur of valley confluences \*Essentially ice ridges protected from the Sun's heat by a surface layer of debris, they are conspicuous features of contemporary valley glaciers \*Most have not survived deglaciation in a recognizable form, though they may produce chains of kettles and hummocky topography on the floors of mountain valleys

Question 123

Mega-Grooves

Answer 123

• Really big grooves (kms / 10s of m) carved in bedrock by glaciers

Question 124

Moraine

Answer 124

• Ridges of till pushed forward or sideways by glaciers. \*Glacially deposited ridges, that were carried on, in or under a glacier.

Question 125

Morphological Classification of Rivers

Answer 125

Straight Meandering Braided Wandering Anabranching/Anastomosing

Question 126

Mountain Arcs

Answer 126

are usually built at convergent tectonic margins. ## Footnote * Complex sequence of folding, faulting and sometimes volcanism as lithospheric plates collide. * Tectonic mountain-building episodes are called orogenies.

Question 127

Mud flow

Answer 127

• Rapid flow of mostly fine sediment and water. • Mud picked up by flash overland flows. • Common in arid regions, canyonlands, submarine environments • Includes lahars: volcanic mudflows initiated by rapid melting of snow and ice. \*Fine grained sand, silt and clay

Question 128

Neap Tide

Answer 128

Smallest range (moon and sun at right angles) \*Tides vary depending on the positions of the sun, and moon around the Earth.. \*the opposition of the graviational attractions of the moon and sun produces tides with a minumum tidal range

Question 129

Normal Fault

Answer 129

A geologic fault in which the hanging wall has moved downward relative to the footwall. Normal faults occur where two blocks of rock are pulled apart, as by tension. A normal fault occurs when the crust is extended. Alternatively such a fault can be called an extensional fault. The hanging wall moves downward, relative to the footwall.

Question 130

Nunatak

Answer 130

a horn protruding from an ice field

Question 131

Outwash Plain

Answer 131

• Broad plains formed by deposits from proglacial braided streams at or beyond the ice terminis \*sands and gravels • Very wide, active. • When dry, becomes the source for fine wind-blown material called loess.

Question 132

Oxbow Lake

Answer 132

An oxbow lake is a U - shaped body of water formed when a wide meander from the main stem of a river is cut off to create a lake. This landform is so named for its distinctive curved shape, resembling the bow pin of an oxbow.

Question 133

Parabolic dunes

Answer 133

* In plan view, parabolic dunes are u-shaped mounds of well-sorted sand with two elongate arms that extend upwind. * Slip faces occur on the outer (convex) side of the nose and on the outside slopes of the elongate arms * often occur in semiarid areas where some precip is common (and Vegetation) * arms are typically anchored by vegetation, and wind erodes sand from the central zone, and deposits it on the leeward slope - central part migrates downwind. * often associated with blowouts, which provides the sand.

Question 133

Oxidation

Answer 133

Chemical weathering ## Footnote * Addition of oxygen to minerals → forms oxides (e.g. rust). * Opposite of reduction * Available O grabs an electron: * Increase in positive valence (e.g. Cu+ → Cu2+); or * Decrease in negative valence (e.g. S2- → S-) * Combination with oxygen 2Zn + O2 → 2ZnO2 * Oxidation of iron-bearing minerals: pyrite ferric sulfuric (ferrous) hydroxide acid * Most effective in the aerated zone: presence of air and water.

Question 135

Physical Weathering

Answer 135

Unloading (pressure release) Thermal Expansion Frost Action Wetting and Drying Salt-crystal growth Root Action

Question 136

Plucking

Answer 136

* Removal of blocks of rock from outcrops by ice. * Exploits rock weaknesses along existing fractures / joints. \*As a glacier moves down a valley, friction causes the basal ice of the glacier to melt and infiltrate joints in the bedrock. The freezing and thawing action of the ice causes cracks in the bedrock through hydraulic wedging. Eventually these joint blocks come loose and become trapped in the glacier.

Question 136

Point Bar

Answer 136

\*Depositional feature made of sand and gravel that accumulates on the inside bend of streams and rivers below the slip-off slope. Point bars are found in abundance in mature or meandering streams. \*They are crescent-shaped and located on the inside of a stream bend, being very similar to, though often smaller than, towheads, or river islands. ## Footnote \*well sorted sediment that typically reflect the overall capacity of the stream. \*very gentle slope and an elevation very close to water level. \*often overtaken by floods and can accumulate driftwood and other debris during times of high water levels. \*A point bar is an area of deposition whereas a cut bank is an area of erosion. \*Point bars are formed as the secondary flow of the stream sweeps and rolls sand, gravel and small stones laterally across the floor of the stream and up the shallow sloping floor of the point bar.

Question 137

Pore Pressure

Answer 137

When pore pressure rises, strength is reduced and stable slopes eventually fail. Groudwater increases pore pressure Pore water pressure refers to the pressure of groundwater held within a soil or rock, in gaps between particles (pores). Pore water pressures in below the phreatic level (see also groundwater) are measured in piezometers. The vertical pore water pressure distribution in aquifers can generally be assumed to be close to hydrostatic.

Question 138

Proglacial lakes

Answer 138

often formed by the damming of a valley by a moraine or ice. • Striking turquoise colour due to glacial rock flour in suspension. \*Is in contact with the ice front along part of its margins.

Question 139

Recurrence interval

Answer 139

\*The average period between two floods of a particular magnitude. \*Means the number of floods of this size over a long period is likely to occur.. • Recurrence Interval (or Return Period) calculated based on occurrence of past flows. * The probability of a flood of any given magnitude is the reciprocal of Ri - (1/RI) * Problems: records are short, spread out, often heterogeneous (ENSO, PDO, mixed flood generation mechanisms). * Useful application: floodplain mapping.

Question 140

Regolith

Answer 140

• Weathering alters the original lithology → what finally remains is an unconsolidated material called regolith or a weathering ## Footnote mantle: i. Smaller particles of rock / primary minerals that resisted destruction. ii. New minerals created by the weathering. iii. Organic material added to the weathered zone. • Note: regolith vs. sediment.

Question 141

Resisting Forces

Answer 141

AKA Shear Strength - Normal compnent of weight - Fricton - Cohesion - Water Content - Moditified Coulomb equation...

Question 142

Reverse Fault

Answer 142

A reverse fault is the opposite of a normal fault—the hanging wall moves up relative to the footwall. Reverse faults indicate compressive shortening of the crust. The dip of a reverse fault is relatively steep, greater than 45°

Question 143

Riffle-pool

Answer 143

the usual channel pattern. o Low-moderate sinuosity. o Moderate sediment transport. \*Undulating beds of gravel that form a sequence of bars, pools, point bars and riffles. The pools are rhythimically spaced, about five to seven channel widths apart. They have moderate to low gradients and are generally unconfied, with well-established

Question 143

Rill Erosion

Answer 143

* If slopes are steep enough and rain intense enough, sheet flow will concentrate into little streams. * These can cut small channels called rills. * Several cm wide / deep * Occur on relatively smooth surfaces. * Parallel rills develop along the slope. Rills may join to form gullies

Question 144

Rip current

Answer 144

\*a strong channel of water flowing seaward from near the shore, typically through the surf line \*Typical flow is at 0.5 metres per second (1–2 feet per second), and can be as fast as 2.5 metres per second (8 feet per second), which is faster than any human swimmer. \*They can move to different locations on a beach break, up to tens of metres (a few hundred feet) a day. They can occur at any beach with breaking waves, including oceans, seas, and large lakes. \*When wind and waves push water toward the shore, that water is often forced sideways by the oncoming waves. This water streams along the shoreline until it finds an exit back to the sea or open lake water. The resulting rip current is usually narrow and located in a trench between sandbars, under piers or along jetties. \*This strong surface flow tends to damp incoming waves, leading to the illusion of a particularly calm part of the sea, which may possibly lure some swimmers into the area.

Question 145

Ripples

Answer 145

Depositional landforms from Aeolian process \*smallest landform, asymmetric • 5–25 cm, h 0.5–25 cm • indicate flow & transport direction • size (h) & spacing (λ) controlled by grain size & windspeed • height controlled by ability of wind to entrain coarser particles from crest • ripple crests are typically coarser on ‘active’ upwind slopes with finer grains in the sheltered lee zone Fluvial Ripples... \*on riverbeds, they may be up to several cm in height and spacing \*Low river velocity and placid water surfaces \*the small amount of sediment that is moved under these conditions is restricted to single grains on the riverbed.

Question 146

Roche Moutonnees

Answer 146

Small Erosional Feature ## Footnote • Asymmetrical rock knobs. • Smooth, gentle up-glacier slope (due to abrasion) - with striations in the direction of flow • Features grooves, striations and polish. • Rough, steep slope down-glacier (due to plucking). \*Most likely to develop near the termini of warm glaciers, where the glacial ice is thinner

Question 147

Rock Basins

Answer 147

* Somewhat streamlined basins, but may be wide in places. * Lengths can extend up to 100’s of km. * Often gouged out of softer rock (e.g. Great Lakes?).

Question 149

Rock Fall

Answer 149

Mass Wasting: Form on a talus (scree) at base of cliff: form talus slopes or debris cones.. Material in the talus is at the angle of repose..

Question 149

Scroll bars

Answer 149

\*Result of continuous lateral migration of a meander loop that creates an asymmetrical ridge and swale topography on the inside of the bends. \*The topography is generally parallel to the meander and is related to migrating bar forms and back bar chutes which carve sediment out from the outside of the curve and deposit sediment in the slower flowing water on the inside of the loop, in a process called lateral accretion. \*Scroll-bar sediments are characterized by cross-bedding and a pattern of fining upward. \*These characteristics are a result of the dynamic river system, where larger grains are transported during high energy flood events and then gradually die down, depositing smaller material with time.

Question 150

Sea Stacks

Answer 150

Erosional Coastal Landscape ## Footnote \*consist of steep and often vertical column or columns of rock in the sea near a coast, isolated by erosion. \*Formed over time by wind and water, processes of coastal geomorphology. \*They are formed when part of a headland is eroded by hydraulic action, which is the force of the sea or water crashing against the rock. The force of the water weakens cracks in the headland, causing them to later collapse, forming free-standing stacks and even a small island.

Question 151

Sediment Calibre

Answer 151

-Determinant of channel form (governing variable): What type of sediment, and therefore what mode of transport? \*important to understand channel morphology response to management (river alterations)

Question 152

Sediment Deposition

Answer 152

• When water slows down, material falls out. * Size reflects energy of environment. * Forms deposits of sediment → bars, bed, floodplain, etc.

Question 153

Sediment Erosion

Answer 153

• Erosional landforms: cutbanks, thalwegs, scour pools, canyons, avulsions, etc. * At the threshold (or critical) bed shear stress (τcr) grains begin to move: factors include: * Grain size * Packing coefficient * Sediment density * Angle of internal friction

Question 155

Sedimentary processes

Answer 155

Erosion Transport Deposition

Question 155

Sediment Load

Answer 155

\*\*FIGURE 10.12 & 10.30 IN TEXT High pulsed - dependent on sediment supply, type of sediment, erodability, slope, veg cover in drainage basin etc Increases with Q (generally) \*Suspended load, dissolved load and bed load... \*\* May vary seasonally or between watersheds \*movement of sediment varies in rivers from place to place and from time to time. Weak weather rock and glacial and other unconsolidated deposits can provide large amounts of sediment from fairly small areas. \*maximum load of sediment is called its capacity.

Question 156

Shear Strength

Answer 156

Resisting Forces ## Footnote \*The max shear stress that a material can withstand without rupture; generally the ability of a material to witshtand shear stress. • Distribution of weight between shear and normal forces depends on slope angle. * Friction (angle of internal friction / repose). * Texture. * Angularity of sediment. * Compaction. * Cohesion. * Water content (groundwater creates ‘pore pressure’). • Modified Coulomb equation: S = c + (σ – μ) tanΦ where S = shear strength c = cohesion σ = effective normal stress (=mg cosβ) μ = pore pressure due to water Φ = angle of internal friction (angle of respose) • Note: in a real slope, structure may be another significant factor…

Question 158

Shear Stress

Answer 158

Driving force = downslope component of weight (mass X gravity) -variable on factors like grain size, packing coefficient, sediment density, angle of internal friction \*The downslope component of the fluid weight exterted on a particle on a bed. -• τ = h\*y\*sinβ\*cosβ where τ = shear stress h = vertical thickness of material above the potential failure plane y = specific weight of material β = slope angle

Question 158

Sheet Erosion

Answer 158

A type of hillslope erosion * Erosion as a result of sheet flow: overland flow that forms a thin layer of water over a smooth surface. * Removes particles in thin layers by precipitation and overland flow.

Question 159

Shield volcanoes

Answer 159

gentle side slopes of only 2-10 degrees - eruptions are rarely explosive - typical of Hawaii

Question 160

Sinuosity

Answer 160

=Curviness May change a river slope

Question 161

Size Classification of Rivers and Discharge

Answer 161

A. Small Channels B. Intermediate Channels C. Large Channels

Question 162

Slope Stability

Answer 162

Mass wasting occurs when driving forces\>resisting forces - Angle of repose - Saturation increases mass wasting chances.. etc.. \*\*FIGUREs 5.5 & 5.7 IN TEXT

Question 164

Slump

Answer 164

Deep seated rotational slide, but not much downslope movement. eg - Dallas \*slumps take place along curved surfaces that are concave upward, and tehy usually extend to greater depths that translational slides. \*Slumps usually require deep perolation of water and thus may take place long after the rain has ended. \*Clay and shale deposits esp vulnerable \*Leaves a steep scarp \*further slumping will continue until a more stable slope of low gradient is attained.

Question 165

Small Channels

Answer 165

• Low discharge (typically 3rd-order or less). • Steep (S between 2º and 20º). o Usually found in headwaters of a watershed. • Usually coarse bed material. • Common channel patterns: 1. Step-pool (steepest). 2. Cascade-pool. o Both low sinuosity. o Low sediment transport.

Question 165

Soft Clay

Answer 165

Earth flow - soil creep - pistol butt trees

Question 167

Solifluction

Answer 167

'Soil flows' \*refers to a wide range of mass movements in a variety of climatic environments.

Question 167

Solution (leaching)

Answer 167

The removal of soil material in solution (chemical weathering) * Dissociation of minerals in water. * Ions added to groundwater, surface water. * E.g. basaltic rocks in Hawaii → karst-like features * No new weathering products. * Salts, gypsum, carbonate are especially prone to this.

Question 168

Spit

Answer 168

Depositional Coastal Landform Long narrow ridges of sand and pebbles attached at one end to the coast and terminating at the other in the sea \*Sediment moving alongshore often builds spits at the mouths of estuaries and at other places where there is an abrupt change in the direction of the coast. \*Most spits extend along the original line of the coast, reducing irregularities

Question 169

Spring Tide

Answer 169

= largest range (moon and sun together or opposed). Tidal range is at it's maximum. \*occurs twice a month, when the sun, moon and earth are roughly aligned.

Question 170

Star Dunes

Answer 170

* Star dunes are isolated, pyramidal, somewhat irregularly shaped to symmetrical mounds of sand with three or more arms radiating from a central high point (with approx radial symmetry) * arms can vary in length, width, number, and shape, but each has a slip face * develop from winds that blow from several opposing directions, either a result of seasonal shifts or where secondary wind flow patterns are produced by topographic barriers * isolated star dunes grow mostly upwards and it’s not uncommon for them to reach heights of 200-300 m. * very low lateral migration rates (cm/yr)

Question 170

Step-pool

Answer 170

morphologically comparable to rapids in small headwater channels \*consist of a staircase series of steps formed by accumulations of large cobbles and boulders that ay be trapped against bedrock obstructions. \*scour pools containing finer material develop downstream of the steps, creating high energy zones, of a characteristic length in which it is unlikely that other steps would be able to form. \*Distance between pools is typically between one and four times the width of the channel.

Question 171

Storm Waves

Answer 171

Tend to ero the berm (barrier, build the beach bar, and lower the beache face (erosional) * Extreme case → at headlands, beach material is completely removed, leaving a rocky point. * NOTE: These relationships are complicated by beach texture. \*the storm wave environments experience a high proportion of short, high-energy waves of varying direction, generated in local waters \*beaches in storm wave environments tend to have dissipative or gently sloping and barred profiles and they are often composed of pebbles or other coarse clastic material.

Question 172

Straight River

Answer 172

* Uncommon in nature → usually in areas of very low stream power (i.e. low slope) or geologic control. * Typically contain alternating pool / riffle sequences. \*usually have bars that alternate as they down downriver and the thalwag meanders a little \*

Question 173

Stratified drift

Answer 173

Glacial meltwater (proglacial streams and lakes) -Depositional landforms occur via transportation of either Ice or Glacier meltwater... Sediments deposited by glacial meltwater that are sorted and layered; a major subdivision of glacial drift that includes river, lake, and marine deposits

Question 173

Stratovolcanoes

Answer 173

Convergent margins.. Subduction -\> plate melts -\> rising magma forms stratovolcanoes \*cones consisting of interbedded lava flows and pyroclastic layers \*Their lava is less fluid like than shield volcanoes and their eruptions are therefore more explosive \*Steep sides - 10-35 degrees

Question 174

Stream capacity

Answer 174

- max volume of debris a stream can carry \*Capacity is directly proportional to the discharge: the greater the amount of water flowing in the stream, the greater the amount of sediment it can carry. \*A stream's competence is a measure of the largest‐sized particle it can transport; competence is directly proportional to a stream's velocity, which can vary seasonally.

Question 175

Stream competence

Answer 175

- max particle size a stream can carry

Question 176

Stream Gauging

Answer 176

\*A stream gauge, is a location used by hydrologists or environmental scientists to monitor and test terrestrial bodies of water. \*Hydrometric measurements of water surface elevation ("stage") and/or volumetric discharge (flow) are generally taken and observations of biota may also be made. \*The location of gauging stations are often found on topographical maps. Some gauging stations are highly automated and may include telemetry capability transmitted to a central data logging facility.

Question 177

Striations

Answer 177

Small erosional feature due to abrasion Generally in the direction of glacial flow \*ca sometimes be seen on clast surfaces \*absent on supraglacially or englacially tranported debris and are found on only a small porportion of the meterial carried at the base of the ice \*Most common on facets and on stones embedded in lodgement till and overridden by the ice \*Some striations may cross in areas where the rocks were rolling.

Question 178

Strike-slip

Answer 178

Faulting: Relative horizontal movement of crustal blocks along nearly vertical fault plane eg - san andreas fault Movement parallel to the strke of the fault surface, so that the blocks on either side of the fault move sideways past each other. Earthquakes along strike slip faults: As two plates try to slide past one another, friction prevents them from moving. Strain builds as a result. Eventually the rock breaks and suddenly releases all this built-up energy in the form of vibrational, or seismic, waves. The seismic waves spread in all directions away from the breaking rock. When these waves reach Earth's surface, they cause the ground to move. This is called an earthquake.

Question 178

Subduction Zone

Answer 178

\*Subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate and sinks into the mantle as the plates converge. \*Regions where this process occurs are known as subduction zones. \*That is, the subducted lithosphere is always oceanic while the over-riding lithosphere may or may not be oceanic. Subduction zones are sites of high rates of volcanism, earthquakes, and mountain building.

Question 180

Sublimation

Answer 180

Solid, directly to gas.. A form of ice loss in the ablation zone

Question 181

Supraglacial Till

Answer 181

-Melt-out till (melting of ice on the glacier surface).

Question 181

Subsidience

Answer 181

Subsidence is the motion of a surface (usually, the Earth's surface) as it shifts downward relative to a datum such as sea-level. The opposite of subsidence is uplift, which results in an increase in elevation. Ground subsidence is of concern to geologists, geotechnical engineers and surveyors. \*IN FAULTING: When differential stresses exist in the Earth, these can be accommodated either by geological faulting in the brittle crust, or by ductile flow in the hotter and more fluid mantle. Where faults occur, absolute subsidence may occur in the hanging wall of normal faults. In reverse, or thrust, faults, relative subsidence may be measured in the footwall. \*ISOSTATIC SUBSIDIENCE: If mass is added to a local area of the crust (e.g. through deposition), the crust subsides to compensate and maintain isostatic balance. The opposite effect to Isostatic subsidence is known as isostatic rebound - the action of the crust returning (sometimes over periods of thousands of years) to a state of isostacy, such as after the melting of large Ice sheets or the drying-up of large lakes after the last ice age.

Question 182

Surface Expression

Answer 182

Terrain symbol mapping... • Surface expression = form (assemblage of slopes) and pattern of forms expressed by a surficial material at the land surface. o Equivalent to “landform” used in a non–genetic sense (e.g., ridges, plain). • Also describe the manner in which unconsolidated surficial materials relate to the underlying substrate (e.g., veneer).

Question 184

Surficial Material

Answer 184

• Non-lithified, unconsolidated sediments. o Produced by weathering, sediment deposition, biological accumulation, human and volcanic activity: o Don’t consider the soil: this is the parent material. o Noted as rock where no other overlying material is present. • Surficial materials have an implied status: active or inactive. o Add a superscript qualifier if reality is different from assumed status. o Examples: • A floodplain showing evidence of recent sedimentation might be labelled as FA, since it is active. • An old landslide deposit which is now vegetated and stable might be labelled CV, since it is inactive. • A boggy area would be labelled O – no qualifier required, since it is active, as assumed. o The G qualifier is used to connote glacial influence. • Use it when there are obvious glacial traces, e.g. kettled floodplain topography → FG; drop stones and distorted varves in a marine deposit → WG. • Also use it if the glacial influence has been inferred by other means.

Question 185

Surging Glaciers

Answer 185

May move up to ~12 km/yr

Question 186

Suspended Load

Answer 186

A sedimentary fluvial processes.. • Suspended (Wash) load transport – Fine sediment in river flow (predominantly suspended sediment) \*amount of solid sediment moved by a river depends on factors including Q, gradient, velocity, roughness of bed, channel morphology and nature of the grains \*occurs more eratically than solution transport \*greatest concentration near the bottom, but material can be elevated by turbulance \*most of the sediemtn is eroded material from the bank, rainsplash erosion or runoff erosion.

Question 187

Swash

Answer 187

Wave induced current.. Forward=swash -Turbulent layer of water that washes up on the beach after an incoming wave has broken. \*The swash action can move beach materials up and down the beach, which results in longshore transport \*The time-scale of swash motion varies from seconds to minutes depending on the type of beach. \*Greater swash generally occurs on flatter beaches. \*The motion plays the primary role in the formation of morphological features and their changes in the swash zone. \*The swash action also plays an important role as one of the instantaneous processes in wider coastal morphodynamics.

Question 188

Swell

Answer 188

• Swells (summer conditions) tend to build the berm, steepen the beach face (depositional). \*Swell waves are fairly consistent in frequency and direction, especially in the Southern Hemisphere - longshore sediment transport is therefore more constant that in storm wave environments.

Question 189

Tectonic landforms

Answer 189

Tectonic margins: rocks deform under stress Folding Faulting Mountain Arcs

Question 190

Tectonics in BC

Answer 190

Question 190

Terrace

Answer 190

\*step-like landform. \*consists of a flat or gently sloping geomorphic surface, called a tread, that is typically bounded one side by a steeper ascending slope, the scarp. The tread and the steeper descending slope scarp together constitute the terrace. Terraces are formed in various ways. Kame Terrace Lacustrine Terrace Wave cut terrace

Question 191

Terrain Mapping

Answer 191

o Divide landscape into morphological units. o Classify terrain polygons. o Uses: landslide hazard, suitability for building, forestry, etc.

Question 193

Texture

Answer 193

Terrain mapping... • Texture refers to the size, shape and sorting of particles in clastic sediments, and the proportion and degree of decomposition of plant fibre in organic sediments. o Lower-case letters.

Question 194

Three types of sediment transport

Answer 194

- suspended (wash) load transport - Bedload transport - Dissolved (solution) load * Sediment load is highly pulsed – dependent on sediment supply * As Q rises, so does river’s ability to erode and transport sediment * Sediment load (Qs) generally increases with Q. * Assuming adequate sediment supply exists… may vary seasonally or between watersheds. * River-bed sediment has shear strength related to texture, bed structure, lithology, etc..

Question 194

Thermal expansion

Answer 194

* Rocks and minerals expand in response to: * Daily heating and cooling. * Seasonal heating and cooling. * Forest fires. * For the process to be effective, frequent extreme fluctuations are needed. * Experiments show that this process is generally not significant, but it may have a more prominent role in deserts.

Question 196

Tombolos

Answer 196

Depositional Coastal landscape \*Beach formations that connect islands to the mainland or islands to islands. Tombolos develop on the lee side of islands because of the shelter provided from strong wave action and the refraction and convergence of the waves behind islands.

Question 197

Translational slide

Answer 197

\*The planar rupture surface is roughly parallel to the ground surface and at fairly shallow depths \*fault lies along discontinuities in the sediment or soil

Question 197

Transform Fault

Answer 197

A massive example of a fault that is transverse to the strike of folded rocks. \*They end abruptly where they are transformed into other types of structures All transform faults are strike-slip faults because rocks on either side of the fault move parallel to the fault itself. But not all strike-slip faults are transform faults -- transform faults only occur at the boundary between two plates.

Question 199

Transverse dunes

Answer 199

* Transverse dunes are a variety of crescentic dune ridge similar to barchanoid ridges, but are much straighter in plan view * most likely dune pattern if winds are unidirectional and sand is free to migrate * usually free of vegetation and form long ridges * the two flanks of transverse dunes have different angles: a gentler stoss side and steeper lee side * Resemble linear dunes, except that they are aligned normal to wind direction and linear dunes have equally steep flanks. * Migrate in a direction normal to their ridges (e.g. along wind direction), while linear dunes migrate longitudinally along the long axis of the ridge.

Question 200

Truncated spurs

Answer 200

Glaciar has chopped off ends of rock ridges to form smoother, truncated spurs.

Question 201

Tsunami

Answer 201

Very long waves that are generated by earthquakes associated with vertical crustal movements. Then, when it hits the shallow water, the wave grows larger, as it still has the energy it did in the deep end, but not the wavelength, so it goes higher.

Question 203

Two main components of moving glacier

Answer 203

Accumulation zone abover the equilibrium line altitude, where snow and ice is gained in winter than is lost in the summer Ablation zone below the ELA, where more snow and ice is lost in the summer that is gained in the winter.

Question 204

Types of Glaciers

Answer 204

1. Alpine 2. Continental glaciers

Question 206

Types of river channels

Answer 206

\*\*FIGURE 11.8 IN TEXT

Question 207

Uncomformity

Answer 207

An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger, but the term is used to describe any break in the sedimentary geologic record.

Question 209

Unloading (pressure release)

Answer 209

* Deeply buried rocks are under high pressure * Erosion removes overburden → rocks expand! * Rocks tend to split into sheets parallel to the topography. * e.g. granitic exfoliation domes (Yosemite) * Produces ‘dilation joints’. * Note: small-medium scale peeling off of rock slabs = ‘spalling’. * Freezing water or chemical precipitation in cracks can assist exfoliation. * Compression can also help.

Question 211

Ventifacts

Answer 211

Aoelian abrasional process.. created by abration by saltating sand grains -wind eroded forms of various shapes and sizes abrasion concentrated at the foot of rocks. creating a pedistal

Question 213

Volcanic Landforms

Answer 213

* Landforms built by extrusion of magma from constricted openings in earth’s surface * Lava and tephra (solid fragments from ash to boulders) cool and form a variety of features. Divergent margins Convergent margins Hot spots * Intrusions may form if magma cools before reaching surface. * May be exposed by erosion later.

Question 215

Wandering Gravel Bed River

Answer 215

* Transitional form between braided and meandering. * Occasional, stable, vegetated islands. \*A common type of iver pattern in mountainous regions is transitional between the braided and meandering states \*laberally unstable gravel-bed rivers consist of stable reaches with single channels alternating with unstable, sometimes breaded reaches with multiple channels \*develop as the supply of coarse, generally glacial sediment is gradually exhausted

Question 217

Wave Refraction

Answer 217

\*\*FIGURE 13.2 IN TEXT * Shoaling causes wave crests to conform to bottom topography. DIAGRAM * They are almost parallel to shore by the time they break. * Wave energy is concentrated on headlands, diffused in bays. * This tends to promote coastal straightening over time (assuming homogeneous coast materials and topography).

Question 219

Wave Shoaling

Answer 219

* Due to bottom friction, waves slow down. or ‘shoal’, when they enter shallow water. * Individual waves in wave sets begin to ‘catch up’. * E must be conserved → C and λ are reduced, so H must increase. * When steepness \> 1, wave is unstable and begins to break. \*the effect by which surface waves entering shallower water increase in wave height (which is about twice the amplitude). \*caused by the fact that the group velocity, which is also the wave-energy transport velocity, decreases with the reduction of water depth. \*Under stationary conditions, this decrease in transport speed must be compensated by an increase in energy density in order to maintain a constant energy flux \*Shoaling waves will also exhibit a reduction in wavelength while the frequency remains constant.

Question 220

Wave-cut terraces

Answer 220

Erosional coastal landform \*narrow flat area often found at the base of a sea cliff or along the shoreline of a lake, bay, or sea that was created by the erosion of waves. \*Wave-cut platforms are often most obvious at low tide when they become visible as huge areas of flat rock. \*Sometimes the landward side of the platform is covered by sand, forming the beach, and then the platform can only be identified at low tides or when storms move the sand.

Question 221

Wavelength

Answer 221

the spatial period of the wave—the distance over which the wave's shape repeats

Question 223

Wavelength properties

Answer 223

Wavelength Height (independent of wavelength - wave steepness is high variable) Period Celerity

Question 225

Weathering

Answer 225

= the in-situ breakdown and alteration of earth-forming materials (rocks, etc.). • Occurs by physical, chemical (and biological) processes. • Note: erosion = removal of the weathered material from its place of origin. • Weathering and erosion usually operate simultaneously.

Question 227

Weathering Front

Answer 227

Interface between weather material and bedrock \*point of contact between regolith and underlying rock

Question 229

Weathering Limited

Answer 229

A part of hillslope erosion process erosion is faster than weathering / sedimentation. • Usually, bare rock is exposed. • Typical of steep slopes.

Question 230

Weathering Mantle

Answer 230

Weathering alters the original lithology -\> what finally remains is an unconsolidated material called regolith or weathering mantle. i. Smaller particles of rock / primary minerals that resisted destruction. ii. New minerals created by the weathering. iii. Organic material added to the weathered zone. • Note: regolith vs. sediment.

Question 232

Wetting and Drying

Answer 232

* Materials swell when wet, shrink when dry → cracking and splitting. * Most effective in clay-rich rocks and sediment. * Clays adsorb water molecules and swell. * Shrinkage upon drying creates cracks → more water penetration. \*soil creep mechanism

Question 233

Whalebacks

Answer 233

* Streamlined, glacial-smoothed hills oriented parallel to ice flow. * Height of 1 to 10 m and a length of 1 m to several km.

Question 235

Why does weathering happen?

Answer 235

* Rocks are formed within the crust: higher P, T * Unstable under surface conditions. * Products of weathering are more stable. * Climate is the main control of the type and rate of weathering: water and temperature. * Other factors: rock type, topography, time, vegetation / organic matter… • Weathering takes advantage of natural weaknesses in the rock: pores, joints, faults, bedding planes, weak mineral veins, etc… * Degree of weathering intensifies as you near the surface → ‘weathering profile’. * The interface between weathered material and bedrock is known as the weathering front. * Physical and chemical weathering operate simultaneously. * Each may affect the character and rate of the other.

Question 236

Yardings

Answer 236

Aeolian abrasion process.. -elongated, wind & sand eroded ridges that tend to occur in groups

Question 237

Coastal erosional features of rock coast

Answer 237

\*\*FIGURE 14.6 IN TEXT

Question 238

Tolmie

Answer 238

- elongated till from north to south - Rock has lots of grooves running N to S - Very steep on North side, smooth slope on other side - Crag and tail

Question 239

Mount Doug

Answer 239

- Rounded rocks - sub angular - variety of rock types - Till with gentle slope - steep on one side - striations - Roch moutonnee

Question 240

Cordova

Answer 240

- elongated hill crest - till - no rock - Drummlin

Question 241

Swan lake basin

Answer 241

Ocean deposited silt and clay to create big deposits when glaciers receeded and land rose Victoria clay

Question 242

Beacon hill park

Answer 242

Glacial moraine -morainal till - steep towards south and small incline to north

Question 243

Trim line

Answer 243

Where glacier has plowed at sides of a valley

Question 244

Flooding

Answer 244

-natural process on rivers. -We use flood-frequency analysis to try and predict how often a floodplain will flood to any certain "height" (elevation above a datum, usually above sea level). -On a floodplain map, isolines show projected levels of flooding for any particular flood level (e.g. the 100-year flood level) based on flood-frequency analysis. (Isolines are like elevation contour lines on a topo map but they show the projected flood level instead of current ground level). Because humans like to live on floodplains, we build levees to try and restrict flooding in developed areas. This doesn't always work out so well - case in point being the flooding in Calgary last spring. ## Footnote

Question 245

Anostamising

Answer 245

The term anabranching river describes a river with many anabranches, whilst an anastomosing river is an organic-rich subset of this river type. Anastomosing develops in the lower stretches of rivers, where sediment is fine grained