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Geomorphology
Landforma: Karst, Eolian, Glacial, Periglacial, Coastal, Volcanoes, Tectonic, Arid
97
Geology
Undergraduate 4
05/14/2013

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Term
karstification
Definition
weathering, erosion in regions of carbonate rocks & evaporites
Term
karst - climates where they develop
Definition
temperate & tropical
Term
karst formation factors
Definition
-permeability & porosity
-secondary porosity along fractures, joints, faults, etc
-bedding thickness (massive,is better, insoluble materials concentrate along bedding planes & restrict water flow)
-available relief (height above baselevel should permit circulation of water)
-warm, wet (chem rxns occur faster at higher temps, lush veg & microbe activity = tropical soil water with high partial pressure of CO2
Term
zone of aeration
Definition
pore spaces occupied by air & H2O
Term
capillary fringe
Definition
all pore spaces occupied by H2O, held in tension, H2O wont drain freely
Term
phreatic zone
Definition
H20 drains freely b/c hydrostatic P exceeds atm P
Term
water table
Definition
hydrostatic P = atm P
Term
aquifers
-unconfined
-confined
Definition
lithologic bodies that store & transmit H2O
-open to atm & hydrostatic level, upper boundary is water table
-has a confining layer (aquitard) between it and the surface
Term
artesian flow
Definition
confined aquifer, groundwater under positive P
Term
diffuse flow, aquifer
Definition
cavities limited in size & #, caves rare, well-defined water table present
Term
free flow, aquifer
Definition
water moves through integrated conduits under influence of g, flow can transport sediment discharge through springs
Term
confined flow, aquifer
Definition
water moves in response to pressure
Term
exsurgences, springs
Definition
from flow in diffuse aquifers, fed by seepage
Term
resurgences, springs
Definition
fed by groundwater moving through distinct conduits
Term
closed depressions, dolines/sinks/sinkholes
Definition
closed hollow of small/moderate size. wider (10-100m) than deep (2-100m). circular/elliptical, usually in groups
Term
closed depressions, solutional
Definition
water infiltrating into joints & fissures enlarges cracks by solution, funct of slope (low is best), vegetation & soil cover (more increases solution)
Term
closed depressions, collapse
Definition
depressions initiated by solution occurring beneath the surface
Term
closed depressions, uvalas & poljes
Definition
larger than dolines, as dolines enlarge they coalesce into hallows with undulating floors
Term
karst valleys, allogenic
Definition
originating in impermeable rocks adjacent to karst area
Term
karst valleys, blind
Definition
valley terminates at a cliff face due to a sink
Term
karst valleys, pocket
Definition
begin where groundwater resurges as springs
Term
karst valleys, dry
Definition
don't have well defined water courses, or carry only ephemeral flow when flooding
Term
karren (minor solution features)
Definition
groves, pits, flutes, pinnacles, ect. of cm to a few m in size
Term
cockpits
Definition
depressions around cones, tropical climate
Term
phytokarst
Definition
type of karren that develop into sponge-like pinnacles under biochemical aciton of blue-green algea, tropical
Term
caves
Definition
natural underground cavities that include entrances, passages & rooms
Term
development of caves
Definition
1. above water table, corrosive action of vadose water
2. beneath water table, deep circulation of phreatic water
3. at water table, in shallow phreatic zone
Term
abrasion
Definition
grinding, most effective for soft rocks blasted by hard sand, <= 2 m
Term
ventifacts
Definition
faceted stones, perpendicular to the prevailing wind
Term
yardang
Definition
elongate ridges 10-30 m high, parallel to prevailing wind on outcrop
Term
grooves
Definition
parallel furrows in bedrock at various scales
Term
deflation
Definition
removal of sand, erosional
Term
pans
Definition
deflated basins up to 100's of km2
Term
deflation hollows
Definition
smaller than pans
Term
blow-out
Definition
scoop shaped hollows
Term
ripples
Definition
.01-100 cm high
up to 20 m apart
funct of wind v, particle size, type of ripple
Term
dunes
Definition
3-100 m high
occur in groups, regular spacing
conditions favor sand deposition (ex: topographic irrecularity)
balance between volumes of erosion & deposition
maintained through adjustment of backslope & slipface
angles controlled by particle size & velocity gradients
advance in tractor tread fashion
Term
draa
Definition
20-450 m high
Term
dunes, transverse
Definition
perpendicular to prevailing wind, abundant sand, constant wind
Term
dunes, barchan
Definition
limited sand, constant wind, arms in direction of wind
Term
dunes, parabolic
Definition
perpendicular to wind, arms fixed by vegetation, arms opposite direction of wind
Term
dunes, longitudinal
Definition
parallel to wind, spacing controlled by large-scale wind vortices
Term
dunes, seif
Definition
A sharp-crested longitudinal sand dune common to the Sahara and ranging up to 300 m (984 ft) in height and 300 km (186 mi) in length.
Term
dunes, coppice
Definition
fixed by vegetation clumps
Term
dunes, star
Definition
alternating wind directions
Term
dunes, cliff, climbing, lee
Definition
name WRT position, with other features
Term
clay dunes, location
Definition
near coastal lagoons or evaporating salt flats, clay aggregates into pellets, moves into dunes, stabilizes due to rain & salt solution, slopes <= 15 degrees, steepest on windward side <=15 m high
Term
loess
Definition
homogeneous, unstratified silt, up to 100 m thick, highly porous, keeps vertical slopes, originates in deserts or glacial outwash, decreases thickness w/ increasing distance from source
Term
creep, glacial
Definition
cold, dry climate, internal deformation of ice, facilitated by continuous deformation, ice begins to deform as soon as it is subjected to stress, allows ice to flow under its own weight
Term
sliding, glacial
Definition
layer of liquid water along base & sides,temperate glaciers
Term
glacial, two components of slide
-regelation slip
-enhanced creep
Definition
-melting & refreezing of ice due to fluctuating pressure conditions
-local increase in stress and flow rate around larger obstacles
Term
surging glacier
Definition
movement may have characteristics similar to kinematic wave, does not require external stimuli such as mass addition (bulge travels from top, down the glacier - large movement in short amount of time at toe)
Term
types of glaciers, morphological
Definition
based on glacier size & environment of growth
Term
types of glaciers, dynamic
Definition
based on observed activites of glaciers
Term
types of glaciers, thermal
Definition
based on temperature of ice
Term
morphological glaciers, cirque
Definition
bowl-shaped, close to drainage divide, deep, erosional, semicircular depression at the head of a mountain valley
Term
morphological glaciers, valley
Definition
flows past the cirque, down a valley
Term
morphological glaciers, piedmont
Definition
lie beyond the mountain front
Term
morphological glaciers, ice sheets
Definition
override existing topography
Term
dynamic glaciers, active
Definition
continuous movement of ice from accumulation zones to ridges
Term
dynamic glaciers, passive
Definition
not enough new snow, low slopes, very low velocity
Term
dynamic glaciers, dead
Definition
no internal transfer of ice from accumulation zone
Term
thermal glaciers, temperate
Definition
ice throughout mass is at pressure-melting point, abundant melt water, high velocity, erosion active
Term
thermal glaciers, polar or cold
Definition
absence of meltwater - ice at base is frozen to underlying rock, slippage cant occur, movement is internal, low erosive action
Term
glacial budget
Definition
mass balance, budgeting of gains & losses of mass on glacier during specific time interval
Term
temperate glaciers
Definition
high accumulation & ablation rates, move rapidly
Term
polar glaciers
Definition
low accumulation & ablation rates, passive
Term
stratification (ice structures, primary)
Definition
layers/bands within ice due to annual cycle of snow accumulation & ablation - debris & textural differences separate bands
Term
foliation (ice structures, secondary)
Definition
layering produced by shear during ice motion, alternating clear blue & white bubble-rich ice
Term
crevasses (ice structures, secondary)
Definition
cracks in ice surface, reflect tensional stress, usually perpendicular to direction of max elongation
Term
splay/radial crevasses
Definition
near centerline where spreading exerts component of lateral extension
Term
chevron/en echelon crevasses
Definition
near ice margins where shear stress is parallel to valley walls & crevasses form diagonal to valley sides
Term
transverse crevasses
Definition
where ice extends in longitudinal direction (ex: ice falls)
Term
ogives
Definition
at the base, ice crevasses are closed by compression & a band of dirt-stained ice forms in summer. in winter the ice descending the fall reconstitutes into clear, bubbly ice, the annual down-valley flow produces a series of alternating white & dark bands
Term
abrasion
Definition
scraping from debris carried by ice, dependant on relative hardness of debris & bedrock, amount of debris, velocity of flow (approx .06-5mm/yr)
Term
quarrying/plucking
Definition
quarrying: eroding bedrock
plucking: carrying sediment
ice exerts shear F on rock loosened by fractures & meltwater freezes to rock as glacier thickens
Term
abrasion features, striations
Definition
mm deep, continuous only for a short distance
Term
abrasion features, grooves
Definition
1-2 m deep, 50-100 m long, formed by boulders carried along with glacier
Term
abrasion features, crescentic marks
Definition
chipping of underlying rock
Term
plucking features, roche moutonnee
Definition
abrasion upstream & pluckig downstream, promoted by irregular spacing of bedrock features
Term
nivation
Definition
erosion by cirque glaciers - move by rotational sliding as ice slides & rotates
Term
nunatak
Definition
tall residual peaks that stick above the ice when cirque glaciers merge to form an ice cap
Term
fjord
Definition
glacial trough partially submerged by ocean, development occurred when ice was physically beneath ocean
Term
glacial drift
Definition
all deposits associated with glaciation, covers 8% of earths surface above sealevel, 25% of North America
Term
till
Definition
nonstratified, transported & deposited by ice, unsorted, many lithologies, angular
Term
basal/lodgement till
Definition
nonstratified, deposited in subglacial environment, under pressure of overlying ice
Term
ablation till
Definition
nonstratified, debris concentrated at/near the surface & dropped as the ice melts
Term
fabric, glacial
Definition
type of till & mode of emplacement are determined from texture of deposit/arrangement of particles, orientation of clasts through motion (lodgement till)
Term
fluvioglacial
Definition
stratified drift, sediment transported by moving water before final deposition, sorted, rounded
Term
outwash
Definition
stratified drift, sediment deposited beyond terminal margin of the ice in proglacial environment - well sorted, rounded sands/gravels from bedload of stream channels
Term
proglacial, sandur (plural sandar)
Definition
large plain of outwash, similar to alluvial fans
large sediment supply and high floods
jokulhlaup - glacial outburst flood, sudden release of lake water dammed within ice, lifts up ice, when flow lowers, ice slams back down stopping flow
Term
proglacial, valley sandur
Definition
created by 1 main river & and branches
Term
proglacial, plain sandur
Definition
sandar are composed of sand & gravel (fined deflated)
Term
three zones of sandar
Definition
proximal
intermediate
distal
Term
zone of sandar, proximal
Definition
close to ice, rivers entrenched, pitted surface
-kettled sandar
Term
zone of sandar, intermediate
Definition
channels wide, shallow, braided & rapidly laterally shifting
Term
zone of sandar, distal
Definition
channels so shallow that rivers manage to merge into a single sheet of water at high flow
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