Kupfer
Aeolian geomorphology
wind as a geomorphic agent
what are the two processes of aeolian erosion
deflation and abrasion
deflation
erosion of particles as wind picks them up and moves them
abrasion
erosion by windblown particles
wind speed
higher winds means more erosion
surface cover and roughness
alter wind speed by absorbing and deflecting part of the wind energy away from erodible soil
soil texture and cloddiness
affects cohesion and erodibility of soils
soil moisture
moist soil is more cohesive and thus experiences less wind based erosion than dry soil
fetch
distance the wind blows without encountering a barrier
desert pavement
removal of find particles by wind and surface flow leaves a surface of larger stones
what does abrasion lead to
smoothing or pitting of surfaces
ventifact
a rock that has been abraded, pitted, etched, grooved, or polished by wind-driven sand
mushroom rocks
near the base, the material carrying capacity of the wind is at its max, so abrasion is maximized. In some cases, the presence of harder rock strata above a softer rock contributes as well
yardangs
form where winds are strong, unidirectional, and carry an abrasive sediment load. The wind cuts down low-lying areas into parallel ridges which gradually erode into separate hills.
what does distance and height of transport depend on
wind velocity and particle size
where is transported material deposited
where wind velocity decreases
What are the various types of dunes
barchans, transverse, seifs, parabolic, star
what is another word for a barchan dune
crescentic
what is another word for a seif dune
longitudinal dune
what is another word for a parabolic dune
blowout
what is loess
windblown silt
Dunes can move while maintaining a constant shape
TRUE or FALSE
TRUE
sand dune
wind sculpted accumulation of sand
sand dunes form where
there is a plentiful supply of sand
there is little surface protection and cohesion
a natural trap causes the wind to drop the sand
barchans
crescent shaped dunes with horns pointing downwind from the dominant wind direction
transverse dunes
barchans can become aligned together along a plane perpendicular to the wind. If the line becomes somewhat straight, the resulting dune ridges form these
longitudinal dunes
long, straight sharp crested dunes with two slip faces that are aligned parallel to the wind direction
What type of dune is associated with bidirectional winds
longitudinal dunes are
parabolic dunes
formed from blowouts where the erosion of vegetated sand leads to a U shaped depression. the elongated arms, which are located on the upwind side, are often held in place by vegetation
star dunes
pyramidal dunes with slipfaces on three or more arms that radiate from the high center of the mound
what occurs where winds shift and there is no prevailing wind direction
star dunes do
loess
wind deposited blankets of silt and clay
What did loess originate as
silt ground up and deposited by glaciers during ice ages. it was then picked up and deposited farther east by wind, forming blankets of silt
bluffs or cliffs and pillars form
due to vertical jointing
high drainage density is due to
high erodibility of loess
What are extrabasin transfers of fine material important to
explaining local soil chemistry and nutrient budgets
reg
stony depressions and flats
hamada
high barren rocky plateaus
when sands, silts, and clays are carried away what happens
they leave a coarse surface deposit of pebbles and stones
erg
broad, sand seas covered with wind swept sand with little or no plant cover
what is an erg
a desert area that contains more than 48 square miles of aeolian sand and where sand covers more than 20% of the surface
dune fields
smaller ergs
Are ergs erosional or depositional
depositional
regs are a
depression with desert pavement
dry rivers are called
washes or arroyos
mesas
tablelands/plateaus with a flat top and sides that are usually steep cliffs
buttes
isolated hills with steep, often vertical sides and a small, relatively flat top
what is another word for a pinnacle
needle
pinnacle
an individual column of rock, isolated from other rocks or groups of rocks, in the shape of a vertical shaft or spire
alluvial fan
when water flows out of mountains onto the desert floor, it slows down and deposits material forming a fan shaped feature similar to a delta
bajada
merging of alluvial fans creates a ramp or apron of material at the base of slopes
playa
a usually dry lakebed underlain by fine sediment or salts deposited by shallow lake waters on the floor of a closed basin
salt flat
a flat expanse of ground covered with salt and other minerals formed where water pools and evaporates
pluvial lakes
formed by higher rainfall and or lower evaporation under past climates
geological, climatological and biological proxies (natural archives) indicators or phenomena used to infer past conditions like
fossils, geological deposits, pollen, tree rings, corals, ice cores
drivers of change
factors that change geography
factors that change global climates
factors that change geography
plate tectonics alters latitudes of landmasses, reshapes topography, and changes currents
factors that change global climates
atmospheric composition
milankovich cycles and feedbacks
natural climatic variability
naturally occurring factors that affect global temperatures
What are some naturally occurring factors that affect global temperatures
variations in solar output
factors affecting how solar energy is received, reflected, absorbed, and stored
atmospheric composition
milankovich cycles and feedbacks
sun spots
regions of reduced solar temperatures caused by variations in the suns magnetic field. These have a roughly 11 year cycle
greenhouse effect
heat is trapped in the lower atmosphere by certain gases that allow shortwave, incoming sunlight to pass but absorb longer wave outgoing energy from the planets surface
What has happened throughout Earths history pertaining greenhouse gas concentrations
they have varied naturally which has contributed to changes in earths climate
What do gases injected into the upper atmosphere reflect
incoming solar radiation back to space, causing cooling
Milankovick Cycles
eccentricity
obliquity
precession
eccentricity
ellipticity of the earths orbit
obliquity
tilt of the earths axis: 22.1 degrees - 24.5 degrees
precession
orientation of the earths axis
Milankovich cycles interact with feedbacks in
albedo
concentrations of greenhouse gases
oceanic circulation
Eustatic sea level changes
changes in glacial extent during the quaternary have also led to changes in sea level related to the freezing or melting of great masses of ice
glacier
large mass of perennial ice formed by the accumulation and recrystallization of snow under pressure
as now accumulates it is compressed, becoming more dense and forming
neve
alpine glaciers
located in mountains; largely confined to areas within valley walls
continental ice sheets
large, unconfined glaciers that cover continental areas
accumulation
new inputs of snow
ablation
losses of ice
mass balance
accumulation - ablation
internal plastic flow
weight of the overlying glacier causes glacial ice to move like a slow moving plastic river
near the surface of the glacier, the ice is more brittle and cracks, forming
crevasses
zone of accumulation
snow input is higher than melt; net accumulation feeds ice flow downslope
zone of ablation
snow input is less than melt; melting more rapid than accumulation so relies on ice flows above
plucking
rocks are loosened, detached and carried away by the glaciers movement
abrasion
plucked debris grinds across bedrock, scouring away material
What two ways can material be transported
by meltwater streams running through and out of a glacier
by the ice within or on top of a glacier
deposition by meltwater streams running through and out of a glacier
glaciofluvial deposits, valley train
by the ice
till, moraines
valley train deposit
glacially eroded material that is deposited by meltwater streams beyond the furthest extent of glaciation
Till
blanket of eroded material all sizes that is dropped as a glacier retreats
moraine
ridge of unsorted glacial material piled up at the edge of a glacier by internal plastic flow
cirque
a scooped out bowl shaped basin at the head of an alpine glacier
horn
a pyramidal peak that results when several glaciers create cirques on various sides of a mountain
arete
a sharp ridge dividing two cirques or glacial valleys
tarn
a small glacial lake
U shaped glacial valley
glaciated valley that takes on the shape of a U
hanging valley
valleys of tributaries left stranded high above a glaciated valley floor
paternoster lakes
small stair stepped lakes running down a glaciated valley
fjord
a long, deep, narrow sea inlet formed by submergence of a glaciated valley formed by eustatic sea level rise