Chapter 15 and 16

Question 1

Aeolian system

Answer 1

wind a general part
of the circulation of the atmosphere

Question 2

What is the aeolian system driven by? In what sorts of places?

Answer 2

Driven by solar energy. Wind is an effective agent when vegetation is
scarce (arid, glacier, coastal)

Question 3

Where does brittle fracture occur?

Answer 3

Arid environments where breakdown is primarily brittle fracture,
regolith tends to be stony, sand and silt-grade material.

Question 4

Sediment movement

Answer 4

Air retarded by friction with ground.
* Boundary layer condition – air is not moving at the surface
* drag velocity U*
* critical threshold velocity: threshold at which sediment moves

Question 5

entrainment of particles by wind occurs?

Answer 5

Balance between resisting and impelling forces
-variation in atmospheric pressure can depress or raise sea level (low pressure Hurricanes sea surges)
-creates the intertidal habitat to which a range of plant and animal organisms that are adapted and which have geomorphological effects
-with each tide an influx of nutrients are brought in

Question 6

Resisting forces

Answer 6

inertia,
* friction,
* cohesion

Question 7

Impelling forces

Answer 7

• drag force,
• lift force,
• ballistic impact

Question 8

Waves

Answer 8

-wave action is probably the most important agent of coastal change
-wave is measured by the wavelength and height of the wave
-wind speed, duration of wind, and fetch determine wave height
-waves travel faster in open water
-waves travel slower in shallower water

Question 9

saltation

Answer 9

process involving the movement/transportation of particles such as sand or soil by wind or water
-involves a bouncing or hopping motion where particles are lifted from the surface and then brought back down again, often to be lifted again

Question 10

inertia

Answer 10

the tendency for objects at rest to remain at rest and for objects in motion to continue in motion unless acted upon by an outside force
-property that opposes attempts to put an object in motion or to change the magnitude or direction of its velocity

Question 11

friction

Answer 11

the force that resists the sliding or rolling of one solid object over another

Question 12

cohesion

Answer 12

describes particles that are the same tend to stick together

Question 13

drag force

Answer 13

the force of wind or air resistance pushing in the opposite direction to the motion of the object (aerodynamics of a plane); friction caused by air, which opposes motion

Question 14

lift force

Answer 14

the force exerted by moving air (wind) on a surface; acts in an upward direction in order to counter the force of gravity; a mechanical force generated by a solid object moving through a fluid

Question 15

Erosion by wind

Answer 15

• Removal of surface sand – leaves behind stones – desert pavement or reg
• Wind faceted stones are called ventifacts

Question 16

Aeolian deposition

Answer 16

process of dune formation
* Ripples
* Desert Dunes
* Coastal Dunes

Question 17

Three types of currents

Answer 17

longitudinal, transverse, surface

Question 18

nearshore dynamics

Answer 18

-waves transport sediment
-swash and backlash

Question 19

swash and backwash

Answer 19

types of wave movement that influence the structure of a beach

Question 20

swash

Answer 20

refers to waves traveling towards the beach, pushing sediment up the shoreline and contributing to coastal deposition.

Question 21

backwash

Answer 21

the movement of water back down the beach and into the ocean, which scours out the beach and carries materials away

Question 22

coastal erosion

Answer 22

if sediment removal>supply, then no beach and wave energy is directed at bedrock plus:
-salt weathering, marine organisms, water layer weathering…

Question 23

costal deposition

Answer 23

-leaving beaches(whether there is more deposition than removal of materials), sand dunes, tidal flats, and estuaries

Question 24

ripples

Answer 24

caused by the interaction of wind and water, or the physical interaction of the water with another object

Question 25

coastal dunes

Answer 25

• An embryo foredune may form which traps further sand.
• Positive feedback during development
• Energy is absorbed, saltation declines and deposition occurs
• Inland migration of the dune mass, and new dune formation
• Vegetation stabilizes the dune
• When disturbed by humans or animal blow out can occur

Question 26

coastal conclusion

Answer 26

-coastal processes are dominated by mechanical energy transfers at variety of temporal scales
-coasts are rapid-response systems that adapt to new equilibriums (overall younger systems)
-they are under threat from rising sea levels

Question 27

coastal system

Answer 27

• Coasts occur where the world’s oceans and seas meet the margins of
  the land masses.
• Estimates that 65% of world’s population lives within a few kilometers
  of the coast.

Question 28

Coastal sources of energy

Answer 28

tides and waves

Question 29

Tides

Answer 29

originate from the gravitational pull of the moon and sun in
combination with the rotational energy of the earth

• Regular oscillations in tide level are created subject to biweekly variation can range from
  0.5-10 m
• Variation in atmospheric pressure can depress or raise sea level (low pressure Hurricanes
  sea surges)
• define the range of elevation in which direct wave and other marine action takes place
• flow and ebb of tides around coastal irregularities create tidal currents
• diurnal alternations of inundation and exposure of the intertidal zone create conditions for
  particular rock weathering processes
• create the intertidal habitat to which a range of plant and animal organisms is adapted and which
  may have geomorphological effects
• With each tide an influx of nutrients is supplied to intertidal organisms

Question 30

Waves

Answer 30

are created by the wind shear across the ocean (ultimately powered
by solar energy)

Question 31

What is the most important agent of coastal change?

Answer 31

wave action

Question 32

What determines wave height?

Answer 32

Wind speed, duration
of wind, and Fetch
determine

Question 33

Where do waves travel faster?

Answer 33

in open water

Question 34

Where do waves travel slower?

Answer 34

in shallow water

Question 35

What do currents do?

Answer 35

Currents (wave induced, tidal, wind-induced) transport sediments and
may entrain sediments

Question 36

salt weathering

Answer 36

a form of mechanical weathering or physical weathering of rock that occurs when salt spray from the sea gets into a crack in a rock, evaporates and crystallizes putting pressure on the surrounding rock and weakening its structure; most common in arid climates