Module 11 Flashcards
Describe typical landforms created by aeolian activity in arid landscapes
(transverse dunes, parabolic dunes, blowout dunes, desert pavement, ventifacts, yardang, loess deposits)
Transverse dunes: weak wind in one direction, large amounts of sand deposited perpendicular to the win
Parabolic dunes: arms stabilized upwind by vegetation, often starts as semicircular blowouts that elongate downwind
Blowout dunes: localized deflation basins in highly vegetated areas
Desert pavements: fine particles are removed from the surface by wind or percolated by water, leaving only larger pebbles, gravels, and rocks
Ventifacts: Rocks exposed to aeolian abrasion appear pitted, fluted, or polished
Yardang: large scale streamlining rock structures that are aligned parallel to the most effective wind direction
Loess depositions: wind-blown silt with high moisture and nutrient capacity and cohesive sediments that maintain nearly vertical faces in outcrop
Distinguish between the terms oceans, seas, gulfs and bays.
Oceans refer to the largest bodies of salty water
Seas are subdivisions of oceans that are partially enclosed by land
Gulfs are smaller arms of an ocean or sea that is also partially enclosed by land
Bays are small indentations along a coast that are connected to an ocean, sea, or gulf
Define the term salinity. What factors influence ocean salinity?
Salinity refers to the concentration of dissolved solids in seawater, varying between 34 and 37 parts per thousand (%)
Influenced by evaporation, precipitation and river discharge
Describe the physical characteristics of wind-generated (gravity) waves
[wavelength, wave height, wave amplitude, wave steepness, wave base]
The horizontal distance between successive wave crests or troughs is the wavelength.
Wave height measures the vertical distance between the wave crest and the base of the wave trough
Wave amplitude refers to the vertical distance between the wave crest and the water’s surface if it were still
Wave steepness is the angle of the waves
the diameter of individual oscillations progressively becomes less until they disappear at the wave base
Describe the processes that contribute erosion of rock and sediment at coastlines: wave-cut bluff, wave-cut platform, sea stacks, marine terrace.
Wave-cut bluff: a vertical face that commonly forms along rocky shorelines
Wave-cut platform: the waves cut a vertical face into the rock outcrop, and at the same time they plane a more horizontal surface called a wave-cut platform into the rocks in front of it
Sea stacks: detached fragment of sea arch
Marine terrace: represents the former position of the active shoreline on the landscape
Describe the processes of sediment transport and deposition of sediments at coastlines; berms, offshore bar.
Berm is ridge formed at the high water line of the beach
Offshore bar is a submerged ridge; zone where waves break
Thus the water erodes the sediments at the berm and deposits them on the offshore bar
Describe the processes that contribute to coastal sand dune development.
Coastal dunes develop because of the abundant supply of sand from adjacent beaches
A foredune develops where shore vegetation traps sand blown by the wind off the beach and gradually forms a linear dune
