GEOGRAPHY EXAM 5
antarctica has what percentage of global ice?
90%
glacial valley shape
U-shape
river valley shape
V-shape
cirque
a broad amphitheater hollowed out at the uppermost head of a glacial valley very steep, perpendicular, head and side walls and a floor that is either flat, gently sloping, or even gouged enough to form a basin marks the place where an alpine glacier originated
oxbow lake
a cutoff meander that initially holds water
speleothems
a feature formed by precipitated deposits of minerals on the wall, floor, or roof of a cave
recessional moraine
a glacial deposit of till formed during a pause in the retreat of the ice margin
terminal moraine
a glacial deposit of till that builds up at the outer most extent of ice advance
bergschrund
a large crevice opens at the top of the glacier, exposing part of the headwall to frost wedging people can fall into the crack and are preserved-they move through the ice and come out at the end
flood plains
a low-lying, nearly flat alluvial valley floor that is periodically inundated with flood waters formed where a meandering stream flows across a wide, nearly level valley floor
stream capacity
a measure of the amount of solid material a stream has the potential to transport, normally expressed as the volume of material passing a given point in the stream channel during a given time interval
stream competence
a measure of the particle size a stream can transport, expressed by the diameter of the largest particles that can be moved depends mainly on flow speed, with the power of the water generally increasing by the square of its speed- if flow doubles (2) squared= 4 times the power if flow triples (3) squared= 9 times the power
knickpoint
a sharp irregularity (waterfall, rapid, cascade) in a stream-channel profile
collapsed caves
a sinkhole that results from the collapse of the roof of a subsurface cavern may have vertical walls or overhanging cliffs
horn
a steep-sided, pyramid-shaped mountain peak formed by expansive quarrying of the headwalls where three or more cirques intersect
hanging valley
a tributary glacial trough, the bottom of which is considerably higher than the bottom of the principal trough that it joins
glacial troughs
a valley reshaped by an alpine glacier, usually u-shaped
the sides of a hot spring are colorful due to
algae growth
depositional landform
all materials moved & deposited by glacier "Drift"
accumulation zone
all parts of the glacier above equilibrium line
ablation zone
all parts of the glacier below equilibrium line
Drainage basins/ watershed
all the area that contributes overland flow, streamflow, and groundwater to that stream consists of a stream's valley bottom, valley sides, and those portions of the surrounding interfluves that drain toward the valley every stream of any size has its own, but for particular purposes the term is often reserved for major streams
periglacial zone
an area of indefinite size beyond the outermost extent of ice advance that was indirectly influence by glaciation
glacial erratics
an isolated large boulder carried by the glacier and dropped
a 100 year flood has what probability in any given year?
anytime 1% chance
glacier flow versus glacier advance
as long as a glacier exists, the ice in it is flowing-this does not necessarily mean that the outer edge of the ice is advancing the ice in a glacier always moves forward, but the outer margin of the glacier may or may not be advancing, depending on the balance between accumulation and ablation
basal slip
at the bottom of the glacier, in which the entire mass slides over its bed on a lubricating film of water caused by water and heat
Bering Strait
between present-day Alaska and Russia was a dry land bridge, allowing migration of both animals and humans
saltation
bouncing of material on bottom of river bed
valleys can also be extended through
building of deltas at the terminus of a river
kettle
depressions formed when large blocks of ice left by a retreating glacier become surrounded or even covered by glacial drift
terminal/ recessional moraine
develop as glacier recede ridges that mark positions where the ice from was temporarily stabilized during the final retreat of the glacier concave arc that budge outward in direction of ice movement
trellis pattern
develops as a response to underlying structural control alternating bands of tilted hard and soft strata, with long parallel streams linked by short, right-angled segments ridge-and-valley section of Appalachian Mountains Ouachita Mountains in western Arkansas
during glacial periods sea levels
drop
example of erosional landform
finger lakes in NY great lakes formed by glacial erosion Roche Mountonnee- glacial landform
cutoff meanders and oxbow lakes occurs on a
flood plain
plastic flow of ice
flow inside glacier speed ranges from a few cm/day to 100ft in a day faster in center vs edges
esker
formed from river deposits when there was a river inside the glacier
as Antarctica gets warmer melting ice makes oceans
fresh water (less salty)= more ice ice does not freeze as easily (putting down ice when it snows)
moraines
glacier-deposited landforms composed entirely or largely of till growth at the terminus of a glacier
two continental ice sheets remaining
greenland & antarctica
time since pleistocene is called
holocne
hot springs
hot water at Earth's surface resulting from underground water coming in contact with heated rocks or magma and has been forced upward
as stream discharge increases what happens to speed?
increases
point bar
inside of curve where water moves slowest alluvium is likely to accumulate
pleistocene lakes
large freshwater lakes that formed in basins of interior drainage because of higher rainfall and/or lower evaporation during the Pleistocene
lateral moraine
largest depositional feature produced by a mountain glaciation well defined ridges of unsorted debris built up along the sides of valley glaciers
pleistocene
last named ice age began 2.59 mybp on Thursday November 12 at 4 am eded about 11,700 mybp
dissolution process
limestone combines with water and carbon dioxide to produce carbonic acid
soda straws
long, slender, hang down from ceiling; little more than one water drop wide, these delicate hollow tubes may eventually grow into stalactites
drumlin
low, elongated hill aligned parallel with direction ice movement- the end of the drumlin facing the direction which it came is blunt and slightly steeper than the opposite end
u shape valley
maximum glaciation
dedentric pattern
most common drainage pattern random merging of streams, with tributaries joining larger streams irregularly but always at an angle smaller than 90 not controlled by underlying structure
sinuous channel
much more common than straight winding channel found in almost every type of topographic setting sinuosity increases with decreasing gradient
braided channel
multiplicity of interwoven and interconnected channels very flat high load of sediment typical of glacial melt water and areas with dry seasons
where is maximum velocity?
near the surface and in the middle
snowflakes--granular snow---
neve---glacier ice
a fumarole emits
no water, just steam
density increases between
nèvè and glacial ice glacial ice becomes a blueish color
intermittent or ephemeral streams are
only rarely carrying water
cutbank
outside of curve where water moves fastest
nunataks
pinnacles rising able the ice of a highland icefield
how have humans accelerated the forming of sinkholes?
population growth in FL put a heavy drain on its underground water supply, causing drawdown of the water table- as a result, the number and size of sinkholes are increased
v-shaped valley
pre-glacial topgraphy
karst landscapes do not have many..
rivers on the surface, they usually disappear into the caverns
rock shapes- glacial vs rivers
rounded rocks are river rocks
karst topography
rugged hilly areas that has been shaped almost entirely by solution action of limestone formations set of processes & assemblage of landforms
west Antarctica is made up of
scattered islands, not a continuous landmass
meandering channel
serpentine course nearly flat landscape small gradient continuously changes course
straight channel
short uncommon controlled by underlying geologic structure
most of FLs scenic lakes begin as
sinkholes
what is the most common feature of a karst landscape?
sinkholes
moulins
steep drainage shafts in the ice
graded stream
stream in which the gradient just allows the stream to transport its load more theoretical than actual because equilibrium is so difficult to achieve
alluvium
strem deposited sediment typically smooth and round display distinct strata often sorted- deposit is comprised of rocks of just about the same size
disappearing streams
surface runoff that does become channeled does not usually go far before it disappears into a sinkhole or joint crack
rain and snow water percolates into rocks, travels into heated area and comes to the surface depositing
tavertine
white area on mammoth hot springs looks like snow or ice but its is really
tavertine
even in a straight stream the thalweg..
tends to be slightly sinuous
Thalweg
the course of the deepest and fastest flow
valley deepening
the effect of downcutting (action of stream to erode a deeper channel; occurs when stream is flowing swiftly and/or flowing down a steep slope) produces a deep valley with steep sides and often a V-shaped cross section
interfluve
the higher land above the valley walls that separates adjacent valleys some are ridgetops or mountain crests with precipitous slopes, others are simply broad and flattish divides between drainage systems all parts of the terrain not in a valley are part of an interfluve on a interfluve, water will move downslope through unchanneled overland flow until it reaches the lip of the interfluve. there, as the water drops off the lip of the interfluve into the first small gullies of the valley system, streamflow begins
col
the sharp-edged pass or saddle through the ridge if two adjacent cirques on opposite sides of a divide are being cut back enough to remove part of the arête between them
ground moraine
till is laid down from underneath the glacier rather than from its edge
Stream ordering
two numbers that are the same come together, go up 1 length increases w/ order # increase gradient decreases with order # increase
glacial till is
unsorted and unstratified
knickpoint migration
upstream shift in location of a knickpoint due to erosion
West Antarctica
warming faster than East Antarctica melting is faster than originally predicted ice is 8000 ft thick some "dry valleys" with no ice
is the holocene post-glacial or inter-glacial
we dont know
dissolution is more rapid in
wet enviornments
arête
when several cirques have been cut back into an interfluve from opposite sides of a divide, a narrow, jagged, serrated spine of rock may be all that is left of the ridge crest
column
when stalactite and stalagmites come together
piedmont glacier
when the glacier terminated in a nearby valley
glacial calving
when the ice shelf breaks off pieces into icebergs
medial moraine
where a tributary glacier joins a main valley glacier, their lateral moraines (and debris carried on top of the ice) become united at the intersection and often continue together down the middle of the combined glacier as a dark band of rocky debris
surface drainage
where sinkholes occur in profusion, they often channel surface runoff into the groundwater circulation, leaving networks of dry valley
drainage divide
where the drainage basin terminates line of separation between runoff that descends in the direction of one drainage basin and runoff that goes toward an adjacent basin can be a sharp ridge between drainage basins, or it can be a more subtle separation of basins in the form of an interfluve
stalagmite
where the drip hits the floor and grows upward
how does urbanization impact lag time?
where there tends to be less infiltration of rain because much of the region is covered with impermeable surfaces such as pavement and buildings, a heavy rain tends to produce greater and faster runoff into local streams than in areas with more permeable surfaces
stalactite
where water drips from the roof, a pendant structure grows slowly downward like an icicle
