GEOG 272 - Part 2 Flashcards

Question

What is a channel bar?

Answer 1

A bar in a river is an elevated region of sediment (such as sand or gravel) that has been deposited by the flow. Bars are highly mobile deposits – typically found in braided rivers due to the high sediment loads.

Answer 2

● Longitudinal: Found in gravelly braided streams within the river ○ Little migration ○ Elongated ○ Align parallel to direction of flow ○ Excess of sediment ● Lingoid: Found in rivers with strong seasonal variability ○ Forms perpendicular to the flow direction due to changing sediment transport capacity ● Point: found in meandering rivers, opposite of cutbanks along the side of the river

Answer 3

An area where all surface and groundwater ultimately drains into the same outlet (lake, river, or sea)

Answer 4

Dams, embankments ( structures built to hold back water or support raised ground — kind of like man-made ridges or walls.), Flood walls, Stream bypass/straightening rivers

Answer 5

○ Levees: protect land that is normally dry but that may be flooded during rise in water level in a river ○ Dikes: protect land that would naturally be underwater most of the time.

Answer 6

Can be man-made structure built to contain water (natural dams build by beavers) Flood control and water supply stores are two primary purposes for dam construction, and associated benefit is power production to meet the increasing energy demands.

Answer 7

● Relocation of people ● Soil degradation and crop losses ● Sediment trapping and starvation ● Disturbing fisheries (impacting livelihood) ● Changing sensitive species habitats ● Creating reservoir-induced seismicity ● Historical and cultural losses

Answer 8

● Hard engineering management involves using artificial structures, whereas soft engineering management is a more sustainable and natural approach to manage coastal erosion ■ Soft Engineering: This is smaller-scale techniques, more natural, sustainable approaches, focusing on aligning and working with natural processes. Often with less impact on the environment. (Soft engineering is where the natural environment is used to help reduce coastal erosion and river flooding. These methods of coastal protection are more sustainable as they have less impact on the environment and work with the natural coastal processes)

Answer 9

■ Flood defense ■ Protection of large infrastructure ■ Ensuring drinking water supply

Answer 10

Mountains and hills: ■ Soil erosion and mass movements ■ Sediment mechanics ■ Hillslope hydrology ■ Glacial processes River: ■ Fluvial processes ■ Fluid mechanics (streams) ■ Surface hydrology and ground water hydrology Coast, estuary, and sea ■ Estuarine and coastal processes ■ Fluid mechanics (waves)

Answer 11

Occurs when streams slow down when they enter a larger body of water e.g. another stream, a lake or the ocean and the processes are lower than the material properties

Answer 12

○ As a stream flows down a slope, its potential energy decreases and falls to zero as it reaches the sea. ○ A stream can erode Earth’s surface only where it is above base level. ○ When a stream flows into a lake or a larger river, the surface of the lake/river acts as a local base level.

Answer 13

The level or nearly level depositional plane that forms at the mouth of a river (characteristic triangular shape after the Greek letter delta). An irregular progradation of the shoreline directly fed by a river. Created by sediment deposited by a river. Deltas are wetlands and a principal coastal landform, and important for human activities

Answer 14

■ Sediment load ■ Discharge ■ Wave energy ■ Tidal range

Answer 15

■ Arcuate delta: Tide ■ Cuspate delta (pointed): Waves ■ Bird’s foot delta: Fluvial

Answer 16

Natural subsidence: the lowering of land elevation through the compaction of sediments

Answer 17

○ Climate ○ Waves and tides ○ Sea level history ○ Geology

Answer 18

Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun, and the rotation of the Earth.

Answer 19

On shallow continental shelves, along coastlines and within estuaries

Answer 20

Estuarine embayment ● Riverine sediment is deposited ● Tidal processes delivers sediments back to system Delta ● Riverine sediment is deposited ● Longshore currents redistributes sediments ● Waves reworks sediments

Answer 21

Waves, tides and wind

Answer 22

■ Orbital motion of water particles ■ Breaking waves ■ Swash processes

Answer 23

■ Thermal expansion ■ Added water (mostly meltwater)

Answer 24

Longshore: Reflect the net flux of energy parallel to the shoreline due to wave action Return flow (undertow): Average flow near the bed. Upper parts have onshore flow, near the bottom flow is seaward Rip currents: Strong narrow currents that flow seaward through the surf zone in channels – they can be dangerous to swimmers

Answer 25

Wave action

Answer 26

Waves are temporary changes in water level - a single wave involves a rise and fall in water level relative to the mean water level associated with the transfer of energy.

Answer 27

■ A wave possesses potential energy as a result of the position of the wave crest above the wave trough, and kinetic energy caused by the motion of water particles within the wave. ■ This wave energy is generated by the frictional effect of winds moving over the ocean surface. ■ The higher the wind speed and the longer duration and the distance of open water across which the wind blows, the larger the waves and the more energy they possess

Answer 28

● Wavelength (L) is defined as the horizontal distance from two wave crests (or wave troughs). ● Wave height (h) (also called ‘wave amplitude’) is the vertical distance between the wave's trough and crest. ● The time it takes for successive wave crests to pass a stationary point is called the wave period (P).

Answer 29

As a wave form passes, it disrupts the water column to a depth equal to ½ the wavelength (L)

Answer 30

1. The wind speed (μ) must be blowing faster than the transfer of energy from wave crest to wave crest. 2. The amount of time the wind blows, or wind duration (but from a constant direction ~ 15 variation). 3. The fetch length: uninterrupted distance over which the wind blows without a change in direction.

Answer 31

Swell waves: series of waves generated at a distance, therefore also sometimes referred to as ‘old waves’. - Swells can normally be distinguished from wind waves as they are typically longer and rounder as the waves change their shape whilst they lose their energy. They also don't necessarily come from the same direction as the wind you're currently experiencing - At any one time the sea is usually a combination of both wind waves and swell - Swell waves travel faster than short (sharp crested), locally generated sea waves. - Swell waves also have longer wave periods and this is how they are distinguished from the short sea waves on reaching the coast.

Answer 32

● Waves will continue to travel in their direction of propagation with little loss of energy. Waves disrupt the water column to a depth equal to ½ L (wavelength), meaning when a wave enters water that is less than this depth, it ”feels” the bottom and experiences resistance (waves with 20m wavelength (L), shoals at 10m depth of water). ● When waves shoal, they: ○ Slow down ○ Wavelength decreases, but wave period stays the same ○ Height increases and gets steeper ○ The bottom of the wave slows down relative to the top, so crest overtakes trough → waves break ● Waves lose most of their energy during breaking (it gives off sound and heat), and the remaining kinetic energy causes the water to rush up the shore or erosion.

Answer 33

● Spilling waves: waves break gradually over a distance. ○ White water forms at the crest and expands down the face of the wave. ○ Only the top portion of the wave curls over. ○ Light foam may wash gently up the shore. ○ Normally found with a flat bottom beach. ○ It is usually the most observed type of wave. ● Plunging: wave peaks up until it is an advancing vertical wall of water. ○ The crest advances faster than the base of the breaker, curls, and then descends violently into the trough. ○ This type of breaker sometimes causes an explosive sound as trapped air escapes behind the wave. ○ It is usually found on a medium to steep sloping beach, with little wind or an offshore wind. ● Surging: advances at the same rate as the base of the wave, it surges up the beach as a wall of water. ○ It may or may not be accompanied by white water, and is usually found on very steep beaches.

Answer 34

When water rushes up the beach. The slope of the beach limits how far the swash can travel up the beach.

Answer 35

The maximum level the waves can reach on the beach.

Answer 36

○ The sea floor ○ Shoals and islands ○ Currents (e.g. tidal current from an inlet) Wave refraction erodes and smooths coastlines

Answer 37

Storm surge: is the abnormal rise in water-level during a storm, measured as the height of the water above the normal predicted astronomical tide.

Answer 38

1) Low pressure. Sea level will rise approximately 1 centimeter for every 1 millibar fall in air pressure. Storms are always characterized by low pressure and hence the water level under a storm is always raised. 2) Onshore winds. If the wind is directed shoreward, it can pond water against the coast, causing an increase in the water level. 3) Coastal topography. The effect of the storm surge on the coast depends greatly on coastal configuration. Relatively low gradient, funnel-shaped coastal settings are particularly prone to extreme surges

Answer 39

1) Displacement of the seabed by a submarine earthquake 2) A large landslide into the ocean 3) An impulse generated by a meteorite impact striking the oceans

Answer 40

A long narrow accumulation of sand with one end jointed to the mainland and the other projecting out to sea or across an estuary.

Answer 41

An offshore, narrow sandbar that runs parallel to the hinter lying coast. Their formation require: ■ Sufficient wave energy for long short transport of sand ■ An uninterrupted supply of sand flat ■ Shallow coastal topography tectonically stable areas

Answer 42

An estuary is a partially enclosed, coastal water body where freshwater from rivers and streams mixes with salt water from the ocean

Answer 43

Mangroves are a group of trees and shrubs that live in the coastal intertidal zone. They are common in warmer climates Slow-moving waters (caused by flood and ebb tidal movements) allow fine sediments to accumulate. Mangroves provide essential habitat for thousands of species. They also stabilize shorelines, preventing erosion and protecting the land (and the people who live there) from waves and storms

Answer 44

Salt marshes (also called coastal salt marsh or tidal marsh) is a coastal ecosystem in the upper intertidal zone, between land and open saltwater or brackish water, that is regularly flooded.

Answer 45

They are a wave dominated eroional landforms and steep slopes that border ocean coasts. Typically formed by erosion or major debris avalanches and can be found all around the world.

Answer 46

Hardness of the rock

Answer 47

Mass movements, weathering, rock-removal processes (marine processes)

Answer 48

Importance: decreases wave energy, act as a buffer ■ Glacial ice ■ Sea ice ■ Snow + ice on beach ■ Permafrost: also act as buffer

Answer 49

Berm: active ridges parallel to the shoreline formed by swash processes Inactive berm become beach ridges, parallel to the shoreline -> caused by decreased sea level which is caused by isostatic uplift

Answer 50

Integrated Coastal ZoneManagement: An integrated approach that includes a variety of actors. The overall goal of ICZM is a sustainable approach. Essence of ICZM: ■ Minimize disruption ■ Maximize benefits

Answer 51

Beach nourishment ■ Put sand back onto beach ■ Interception of longshore drift by coastal structures ■ Coastal structures ■ Sand mining (dredging) and subsidence Interception of longshore drift by coastal structures Coastal structure Sand mining (dredging) and subsidence ○ Solutions? ■ Multiple purpose coastal areas

Answer 52

○ When the volume of glacial ice increases, as during an ice age, sea level falls. ○ When ice sheets melt, sea level rises

Answer 53

○ Ice age: A succession of alternating glaciations and interglaciations, spanning a period of millions of years or more ■ An ice age includes cycles of glaciation, deglaciation, and interglaciation ○ Glaciation: The period during which continental ice sheets grow and spread outward over vast areas. ○ Deglaciation: When the climate warms or snow fall decreases, ice sheets become thinner and cover less area. Eventually, the ice sheets may melt completely. ○ Interglaciation: A period following deglaciation, but before next glaciation period. Climate is mild.

Answer 54

Plate tectonics, volcanic activity, decrese in sun's energy output, within the last 3 epochs: Pliocene, Pleistocene, Holocene

Answer 55

■ Changing continental positions, particularly large land masses in high latitude or polar locations. Once ice and snow begin to accumulate, a positive feedback related to the high albedo of ice, called polar amplification, occurs. ■ Uplift of continental blocks and mountain building (plate tectonics) which subsequently alter atmospheric circulation patterns. Similarly, the ocean circulation pattern is affected by continental positions and ocean basin structure ■ Decreased output of carbon dioxide into the atmosphere and oceans due to decreased seafloor spreading (CO2 is an important greenhouse gas) ■ Astronomical factors involving the Earth’s rotational and orbital patterns which result in changes in the amount and distribution of solar radiation

Answer 56

The climate and temperature of the Earth are controlled by the seasonal and latitudinal pattern in incoming solar radiation (insolation). Milankovitch Cycles: Temperature on Earth influenced by ● Eccentricity: The Earth’s orbit around the Sun has an ellipsoid shape (not a circle) ○ Roughly every 100 000 years ● Axial Precession: Toll movement (think spinning top movement) around the Earth’s axis. ○ Roughly every ~ 26.000 years ● Obliquity: The tilt angle (Earth does not have a straight up and down position) of the Earth’s axis relative to the Sun ○ Roughly every 41.000 years

Answer 57

Areas beyond the accumulation zone exist even though ablation losses exceed accumulation gains because ice flow from the accumulation zone

Answer 58

A glacier is a mass of ice formed by the accumulation and crystallization of snow. ○ A glacier moves (flows) under the influence of their own mass and gravity. ○ Defining criteria: a glacier is derived from snow and flows

Answer 59

Glaciers form where the combination of cool air temperatures and snowfall permit the accumulation of snow year after year. ■ More snow has to fall and accumulate in the Winter than melts in the summer.

Answer 60

Fresh snow, firn, glacier ice

Answer 61

The formation of a glacier is related to its mass balance dynamics concerning the amount of material entering and leaving a system. Each glacier system has an accumulation and an ablation zone

Answer 62

■ Accumulation zone: the accumulation is greater than the ablation ● This is the zone where material is added, and no mass is lost. ● This zone area will change each year, but is located in the upper parts ■ Ablation zone: the area of the glacier where more mass is being lost than gained. ● It is a process of removing material from the glacier or ice sheet. ● It is located in the lower part of a glacier where the ablation is greater than the accumulation

Answer 63

Glaciers are classified in several ways (e.g. by size and morphology): ■ Unconfined: Ice sheets, Ice caps & Ice shelf ■ Confined: valley glaciers

Answer 64

Where accumulation and ablation are equal

Answer 65

■ Ice sheets (the largest) > 50 000 km2 ● So thick they completely cover the landscape ■ Ice shelves (on the ocean) < 50 000 km2 ● 90% submerged ■ Ice caps (like ice sheets only smaller). - Outlet glacier: Where an ice stream from an ice cap flows into a valley (sometimes flowing into the sea) Piedmont glacier: Where a glacier flows from a valley into an open plain (where it tends to fan out because it loses confinement of the valley).

Answer 66

■ Niche glaciers (smallest) ■ Cirque glaciers ■ Valley glaciers. (largest)

Answer 67

Crevasses: deep open cracks in the ice, reflecting accelerating flow or steps in terrain below the glacier Moulin: well-like shaft (nearly vertical) draining meltwater from the glacier top to glacier bottom

Answer 68

Glacial action abrades the rock into a smooth form as it rides over the rock summit, then plucks bedrock blacks from the lee side, producing a steep, rocky slope

Answer 69

■ Step 1: Ice sheet present. With the ice front stabilized and the ice in a wasting, stagnant condition, various depositional features are built by meltwater. ■ Step 2: The ice has wasted completely away, exposing a variety of new landforms made under the ice.

Answer 70

The term glacial drift includes all varieties of rock debris deposited in close association with glaciers. There are two major types: ● Stratified drift: layers of sorted and stratified sediments (clays, silt, sand and gravel), deposited by meltwater streams or bodies of water adjacent to the ice ● Till: unstratified mixture of rock fragments, ranging in size (from clays to boulders), deposited directly from the ice without water transport . ○ Till: (a) As ice passes over the ground, sediment and coarse rock fragments are pressed into a layer of lodgment till. (b) When the overlying ice stagnates and melts, it leaves a residual deposit of ablation till.

Answer 71

Half come from surface melt, other half comes from calving (flow of ice from interior into the ocean). Calving happens quicker because ice is flowing quicker. It lubricates the bet and the whole ice sheet moves faster

Answer 72

Measure with a stick Altimetry (measure surface elevation changes with laser) Ice flow velocity measurement: - Measure calving rate - GNSS (measures glacio-isostatic uplift) - Gravimetry (measures gravity changes of earth)

Answer 73

Not a lot of ice melts in Greenland because a lot of sea ice breaks up. More sea ice melting, more water in atmosphere, more snow fall

Answer 74

○ Ground material that remains below 0°C for at least 2 consecutive years. ○ Permafrost is a thermal state and is independent of ground material composition or water content.

Answer 75

■ Continuous: 90-100 % ■ Discontinuous: 50-90 % ■ Sporadic: 10-50 % ■ Isolated: <10%

Answer 76

The point where the annual variation in temperature is less than 0.1°C is defined as the “Depth of Zero Annual Amplitude” (ZAA). The depth of this point can vary between 10 and 20 metres below the surface, which depends on the climate conditions and soil. Depth unique to every place

Answer 77

Yes, you have different permafrost thickness depending on mean surface ground temperature

Answer 78

Ground ice is defined as “ all ice occurring beneath the surface of the ground ” When ground/soil drops below 0C all of the water contained in the pores or as groundwater will begin to freeze Ground ice comprises an important component of permafrost sediments and play a significant role in the evolution of periglacial landscapes

Answer 79

Pore ice Segregated ice: ice lenses Ice wedges Inhected ice (frost mounds) Buried ice

Answer 80

Ice content can be expressed as % volume or % dry weight

Answer 81

Any water content that exceeds saturation in unfrozen conditions ■ Because ground ice is solid, it can accumulate past freezing conditions ■ The volume of ice in the ground which exceeds the total pore volume that the ground would have under natural unfrozen conditions

Answer 82

A comprehensive term used to describe large masses of ground ice, including ice wedges, pingo ice, buried ice and large ice lenses

Answer 83

Like a spider web polygon Formation: thermal contraction cracking -> infilling of water, freezing and wedging soil Goes from - 15 to - 40 in a day or two, ground is going to crack Cracks in the same place as it is weakened Cycle repeated over thousands of years, slow incremental accumulation of ice in these cracks

Answer 84

Thermokarst: is both the process and landforms associated with ground subsidence of thawing permafrost. - Before permafrost thaws, ice is creating volume within the permafrost and creating soil structure → collapse of the surface when it melts - Collapse to the point where all the ground you have is soil, no more ice - Thermokarst leads to land surface lowering as the volume of ice occupied in the ground is gone when the ice melts The potentially unstable nature of ground ice makes it sensitive to slight increases in ground temperature. When the volume of ice exceeds the saturated moisture content of its enclosing sediments (excess ice) melting results in terrain instability and widespread thaw subsidence known as thermokarst.

Answer 85

Ecosystem is what is protecting the permafrost, clearing the land → more permafrost melting

Answer 86

Active layer detachments - Slides: active layer - Rapid and accelerating, dry, failure along a well-defined plane, constant velocity profile moves as a cohesive mass - Happens once then its done Retrogressive thaw slumps - Depending on how much ground ice there is, can be active from a couple days to decades - Increased thawing, area becoming unstable

Answer 87

○ Artificially keep soil ○ Make it pretty ○ Water retention

Answer 88

Ice cored hills, usually up to 20m high, formed by freezing of pressurized groundwater within near-surface permafrost They are divided into 2 systems: open (hydraulic) and closed (hydrostatic) Open systems: happen in the discontinuous permafrost zone, groundwater flow under permafrsot Closed system: happens in the continuous permafrost zones, lake basins that re deep enough to not freeze through, lake drains, which removes what was keeping the talik unfrozen, pingo forms due to injection of water and freezing

Answer 89

The dynamic interaction between permafrost and ground water flow (saturated) produces a separate class of permafrost landforms called frost mounds. ○ Frost mounds can be either perennial (form slowly over many years) or seasonal (form during a single winter season but may remain for more than 1 year) Perennial: Pingos and Palsa Seasonal: Frost blisters, icing blisters, and icing mounds

Answer 90

Depends on water sources and where they occur

Answer 91

○ Permafrost is impermeable so groundwater can’t flow through it (groundwater is restricted to unfrozen zones or taliks; usually only the active layer) ○ Hydrology becomes dormant during winter with a few exceptions; is usually only active seasonally (spring melt and early summer) ○ Snow and ice are important seasonal storages for water and runoff

Answer 92

Frost blisters form through injection of water into the active layer as it freezes and the formation of a blister feature complete with an internal ice lens. ○ Water flows in active layer, can get damped by topography or road ○ There in winter, disappears in the summer, can come back in the winter

Answer 93

Caused by slow movement of the glacier. The movement causes curving and shaping of the land beneath the moving glacier Two main processes: Abrasion and Plucking Abrasion: occurring when particles scrape against each other Plucking: Erosion and transport of large chunks of rocks. Water seeps into cracks in and/or around the rock fragments. Rock becomes unstable, picked up and eroded

Answer 94

Composed of ice lenses, not ice core Palsas form through ice segregation in wetlands and the insulating properties of peat

Answer 95

Erratic boulders, eskers, drumlins, kame hills, outwash plains

Answer 96

Glacial Erratics (erratic boulders): Erratics are pieces of rock carried by a glacier and left stranded on bedrock of different composition. Boulder trains are linear or fan shaped deposits composed of large numbers of erratics that came from the same source.

Answer 97

Steep-walled, sinuous ridge of sand and coarse-grained stratified material deposited by streams of meltwater which flow in tunnels within or beneath the ice

Answer 98

Drumlins are asymmetrical hills composed of glacial till. Drumlins are produced by continental glaciers; these are smooth, elongate, parallel hills of reworked glacial drift that are thought to form when glaciers advance over previously deposited drift. ● They are depositional landforms formed beneath the glacier as it moves forward, when the debris load exceeds the capacity of the glacier to transport sediment. ■ The shape and orientation reflect the flow direction of the ice ● The steep slope faces the direction of glacier advance. ■ Clusters are called drumlin fields

Answer 99

Steep-sided conical hill of stratified drift that collected in openings or lakes in the ice sheet

Answer 100

■ Area beyond the margins of glacier where meltwater (as braided streams) deposits sand, gravel, and mud washed out from the melting ice. ■ Water flowing off the glacier during ablation erodes both bedrock and previously deposited till. Meltwater channels, flood plains, spillways and eskers are all the result of running water.

Answer 101

- Till is an unsorted, unstratified deposit of sediment deposited directly by the glacier. It can be laid down under the glacier as it flows or it may be deposited along the edge of the glacier where it is melting. - It ranges in grain size from fine silt and clay to huge boulders, and is one of the most common forms of glacial deposits. - It forms a sequence of ice-contact landforms: including moraines, drumlins and till plains.

Answer 102

Moraines: landforms composed of till deposited at or near the margins of glaciers by moving ice.

Answer 103

○ End moraine: a ridge of till that forms at the terminus of a stationary glacier. ○ Recessional moraine: a series of end moraines formed by a receding glacier that periodically stabilized. ○ Terminal moraine: the last recessional moraine Representing the point of farthest glacier advance. ○ Lateral moraine: only produced by valley glaciers, these are ridges of till paralleling the valley walls, deposited at the margins of the glacier. Sediment is abraded and plucked from valley walls and mass wasted onto the glacier surface. ○ Medial moraine: central moraine formed when two valley glaciers merge and combine their lateral moraines. ○ Ablation moraine: a sheet of till that is deposited as glaciers stagnate and then gradually down waste

GEOG 272 - Part 2 Flashcards

(128 cards)