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Geol 101 - 2nd Exam Review - 2005

Terms

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creep
very slow, downslope movement of soil or unconsolidated debris
debris
any unconsolidated material at Earth's surface, such as soil and rock fragments
debris avalanche
a rapidly moving, turbulent mass of debris, air, and water
debris flow
mass wasting in which motion is taking place throughout the moving mass
debris slide
a coherent mass of debris moving along a well-defined surface
earthflow
debris that moves downsloap as a viscous fluid
landslide
a slow to a very rapid descent of rock or soil
mass wasting
(mass movement) movement in which bedrock, rock debris, or soil moves downslope in bulk because of the pull of gravity
permafrost
ground that remains frozen for many years
relief
the vertical distance between valley floor and mountain summit
rockslide
the rapid sliding of a mass of bedrock along an inclined surface of weakness
rotational slide (slump)
movement along a curved surface - the upper part moving downward while the lower part moves outward
shear force
-parallel to the slope
-indicates the rock's ability to move
slide
-means the descending mass remains relatively intact moving along one or more well-defined surfaces
soluifluction
the flow of water-saturated debris over impermeable material
talus
an apron of fallen rock fragments that accumulate at the base of a cliff
translational slide
the descending mass moves along a plane approx parallel to the slope of the surface
abrasion
the grinding away of the stream channel by the friction and impact of the sediment load
alluvial fan
a large, fan or cone shaped pile of sediments that usually forms where a stream's velocity decreases as it emerges from a narrow mountain canyon onto a flat plain
bar
a ridge of sediment, usually sand and gravel, deposited in the middle or along the banks of a stream
base level
-the limit of erosion of the earth's surface
bed load
the large or heavy sediment particles that travel on the stream bed
braided stream
flowing in a network of interconnected rivulets around numerous bars
delta
a body of sediment deposited at the mouth of a river when the river's velocity decreases
dendritic pattern
-a drainage pattern that resembles branches of a tree or nerve dendrites
-develop on uniformly erodible rock or regolith and are the most common pattern
discharge (of a stream)
the volume of water that flows past a given point in a unit of time
dissolved load
soluble products of chemical weathering processes
distributaries
small, shifting channels that carry water away from the main river channel and distribute it over the surface of the delta
divide
a rich or strip of high ground dividing one drainage basin from another
downcutting
the process of deepening a valley by erosion of the stream bed
drainage basin
the total area drained by a stream and its tributaries
drainage pattern
reveals the nature and structure of the rocks underneath a river
flood plain
a broad strip of land built up by sedimentation on either side of a stream channel
graded stream
one that exhibits a delicate balance between its transporting capacity and the sediment load available to it
headward erosion
the slow, uphill growth of a valley above its original source through gullying, mass wasting, and sheet erosion
hydraulic action
the ability of flowing water to pick up and move rock and sediment
hydrologic cycle
the movement of water and water vapor from the sea to the atmosphere, to the land, and back to the sea and atmosphere again
incised meanders
meanders that retain their sinuous pattern as they cut vertically downward below the level at which they originally formed
lateral erosion
the erosion and undercutting of a stream's banks and valley walls as the stream swings from side to side across its valley floor
meander
sinuous curve
meander cutoff
a new, shorter channel across the narrow neck of a meander
natural levees
low ridges of flood deposited sediment that form on either side of a stream channel and thin away from the channel
oxbow lake
the cutoff meander becomes a crescent-shaped lake that may fill with sediment and vegetation
point bar
a type of sand bar deposited on the inside of curves because of lower velocity there - usually consist of arcuate ridges of sand or gravel
pothole
depressions that are eroded into the hard rock of a stream bed by the abrasive action of the sediment load
radial pattern
a drainage pattern in which streams diverge outward like spokes of a wheel
-they form on high conical mountains like volcanoes and domes
rectangular pattern
a drainage pattern in which tributaries have frequent 90 degree bends and tend to join other streams at right angles
saltation
when sand grains move by traction downstream in a series of short leaps or bounces off the bottom
sheetwash
a thin layer of unchanneled water flowing downhill
solution
gradual dissolving of the rocks in a stream channel
stream
a body of running water that is confined in a channel and moves downhill under the influence of gravity
stream channel
a long, narrow depression eroded by the stream into rock or sediment
stream gradient
the downhill slope of the bed
-controls a stream's velocity
stream terrace
steplike landforms found above a stream and its flood plain
stream velocity
the distance water travels in a stream per unit of time
superposed stream
-shows the origin of mountain ranges that have steep-sided river valleys slicing directly across them
-and old river could have been there and eroded the mountain
suspended load
sediment that is light enough to remain lifted indefinitely above the bottom by water turbulence
traction
movement by rolling, sliding, or dragging
trellis pattern
drainage pattern that consists of parallel main streams with short tributaries meeting them at right angles
tributary
a small stream flowing into a larger one
aquifer
a body of saturated rock or sediment through which water can move easily
artesian wall
a well in which the leve of water is above the top of the aquifer
cave (cavern)
a natuarally formed underground chamber
-they usually form when slightly acidic ground water disolves limestone along the joints and bedding planes
concretion
a hard rounded mass that developes when a considerable amount of cementing material percipitates locally in a rock
confined (artesian) aquifers
confined aquifers
drawdown
local lowering of the water table
gaining streams
-found mostly in rainy regions
-receive water from the saturated zone
-the surface of these streams coincides with the water table
geode
partly hollow, globe-shaped bodies found in some limestones and locally in other rocks
geyser
a type of hot spring that periodically erupts hot water and stream
ground water
the water that lies beneath the ground surface, filling the pore space between grains in bodies of sediment and clastic sedimentary rock, and filling cracks and crevices in all types of rock
hot spring
springs in which the water is warmer than human body temperature
karst topography
describes an area with many sinkholes and with a cave system beneath the land surface
losing stream
-occur in drier climates
-streams that loose water to the saturated zone
-the channels of these streams lie above the water table
perched water table
the top of a body of ground water separated from the main water table beneath it by a zone that is not saturated
permeability
the capacity of a rock to transmit a fluid such as water or petroleum through pores and fractures
-measures the relative ease of water flow and indicates the degree to which openings in a rock interconnect
petrified wood
a type of fossil that develops when porous buried wood is either filled in or replaced by inorganic silica carried in by ground water
porosity
the percentage of rock or sediment that consists of voids or openings
-measures the rock's ability to hold water
recharge
the addition of new water to the saturated zone
saturated zone
the subsurface zone in which all rock openings are filled with water
sinkhole
closed depressions found on land surfaces underlain by limestone
speleothems
deposits of calcium built up in caves by dripping water
spring
a place where water flows naturally from rock onto the land surface
stalagmites
cone-shaped masses of dripstone formed on cave floors, generally directly below stalacites
stalacites
icicle-like pendants of dripstone hanging from cave ceilings
-generally slender and are commonly aligned along cracks in the ceiling
-act as conduits for ground water
unconfined aquifer
has a water table because it is only partly filled with water
vadose zone
the zone above the water table that is generally unsaturated
water table
the makrs of a well on the upper surface of the saturated zone
well
a deep hole, generally cylindrical, that is dug or drilled into the ground to penetrate an aquifer within the saturated zone
ablation (wastage)
when glacier ice moves downward and is eventually lost due to gravity
advancing glaciers
glaciers with positive budgets push outward and downward at their edges is one
alpine glaciation
types of glaciers found in mountainous regions
continental glaciation
a large part of a continent is covered by glacial ice
arete
sharp ridges that separate adjacent glacially carved valleys
basal sliding
the sliding of a glacier as a single body over the underlying rock
cirque
a steep-sided, half-bowl shaped recess carved into a mountain at the head of a valley carved by a glacier
crevasses
open fissures that develop within glaciers
drumlin
bodies of till shaped into streamlined hills
-shaped like an inverted spoon aligned parallel to the direction of ice movement of the former glacier
end moraine
a ridge of till, piled up along the front edge of ice
equilibrium line
marks the highest point at which the glacier's winter snow cover is lost during a melt season
erratic
an ice-transported boulder that has not been derived from underlying bedrock
esker
an outwash feature of unusual shape associated with former ice sheets and some very large valley glaciers
fiord
a coastal inlet that is a drowned glacially carved valley
-common along mountainous coastlines
glacier
a large, long-lasting mass of ice, formed on land that moves under its own weight
ground moraine
a thin, extensive layer or blanket of till
hanging valley
after glaciers disappear, tributaries are left high above the main valley
horn
the sharp peak that remains after cirques have cut back into a mountain on several sides
icebergs
blocks of ice that break free from glaciers and float in a body of water
ice cap
a small layer of ice covering a smaller piece of land
ice sheet
a mass of ice that is not retricted to a valley but covers a large area of land
kettle
a depression in land that forms after an ice block melts
lateral morains
elongated, low mounds of till which form along the sides of a valley glacier
moraines
till that occurs as a body of unsorted and unlayered debris either on a glacier or left behind by a glacier
medial moraine
the long ridge of till in between to adjacent lateral moraines
outwash
the material deposited by the debris-laden meltwater
plastic flow
slowly flowing glacial ice (like molasses)
pluvial lake
lakes formed in a period of abundunt rainfall
receding glaciers
glaciers with negative budgets that grow smaller and their edges melt back
rigid zone
the upper part of the glacier
rock-basin lake (tarns)
lakes that usually form a chain after ice has melted
-form depressions in weaker rock
rock flour
composed largely of very fine particles of unaltered minerals
-produced by the grinding of rock across rock
terminus
the lower edge of a glacier
-moves farther downvalley when a valley glacier has a positive budget
-sometimes it melts back upvalley
theory of glacial ages
states that at times in the past, colder climates prevailed during which much more of the land surface of earth was glaciated than at present
till
the unsorted and unlayered rock debris carried or deposited by a glacier
tillite
lithified till
-shows evidence of older glaciation
truncated spur
ridges that have triangular facets produced by glacial erosion at their lower ends
u-shaped valley
characteristic of Glacial Erosion
v-shaped valley
characteristic of Stream Erosion
valley glacier
glacier that is confined to a valley and flows from a higher to a lower elevation
varve
two layers of sediment representing one year's deposition in a lake
zone of ablation
the lower part of a glacier where ice is lost, or ablated, by melting, evaporation, and calving
zone of accumulation
part of the glaciar with a perennial snow cover
bajada
a broad, gently-sloping depositional surface formed by the coalescing of individual alluvial fans
-very extensive with a gently rolling surface
barchan
a crescent-shaped dune with a steep slip face on the inward or concave side
blowout
a depression on the land caused by wind erosion
butte
a narrow hill of resistant rock with a flat top and very steep sides
deflation
the removal of clay, silt, and sand particles from the land surface by wind
desert
any region with low rainfall
fault
a crack in the soil along which some rock movement has taken place
flash flood
sudden local floods of high discharge and short duration
-more common in arid regions than in humid regions
loess
a deposit of wind-blown silt and clay composed of weathered, angular grains of quartz, feldspar, and other minerals weakly centered by calcite
longitudinal dune
-one of the largest types of dunes
-symmetrical ridge of sand that forms parallel to the prevailing wind direction
mesa
a broad, flat-topped areas elevated above the surrounding land and bounded by cliffs and capped with a resistant rock layer
plateaus
broad, flat-topped areas elevated above the surrounding land and bounded, at least in part, by cliffs
playa
a very flat surface underlain by hard, mud-cracked clay
playa lake
very shallow lakes created by runoff water in desert areas
pediment
a gently sloping surface created by erosion of a mountain
-it is commonly covered with a veneer of gravel, cut into the solid rock of a mountain
rain shadow
as moist air is forced up to pass over a mountain range, it expands and cools,loosing moisture as it rises
sand dune
mounds of loose sand grains heaped up by the wind
-mostly develop in areas of very strong winds
slip face
the steep downwind slope of a dune
transverse dune
a relatively straight, elongated dune oriented perpendicular to the wind direction
ventifact
rocks with flat, wind-abraded surfaces
arch
bridges of rock left above openings eroded in headlands or stacks by waves
barrier islands
ridges of sand that parallel the shoreline and extend above sea level
baymouth bar
a ridge of sediment that cuts a bay off from the ocean and is formed by sediment migrating across twhat was earlier an open bay
beach
a strip of sediment that extends from the low-water line inland to a cliff or a zone of permanent vegetation
beach face
the steepest part of the beach which is exposed to wave action, particularly at high tide
berm
a wave-deposited sediment platform that is flat or slopes slightly landward
breaker
a wave that has become so steep that the crest of the wave topples forward, moving faster than the main body of the wave
coast
all the land near the sea, including the beack and a strip of land inland from it
coastal straightening
takes place on an irregular shore gradually by wave erosion of headlands and wave deposition in bays
crest (of wave)
the high point of a wave
trough
the low point of a wave
estuary
a drowned river mouth
headland
points of land that stick out of a coast next to bays
longshore current
a moving mass of water that develops parallel to shoreline
-its width is equal to the width of the surf zone
longshore drift
the movement of sediment parallel to shore when waves strike the shoreline at an angle
marine terrace
a broad, gently sloping platform that may be exposed at low tide if the shore has significant tidal action
rip current
narrow currents that flow straight out to see in the surf zone, returning water seaward that breaking waves have pushed ashore
sea cliffs
steep slopes that retreat inland by mass wasting as wave erosion undercuts them
spit
a fingerlike ridge of sediment that extends out into open water
stack
erosional remnants of headlands left behind as the coast retreats inland
wave height
the vertical distance between the crest and the trough
wavelength
the horizontal distance between two wave crests or two trophs
surf
breakers - or waves that become so steep that the crest of the wave topples forward
wave refraction
the bending of a wave as it slows progressively along its length and changes direction and becomes more nearly parallel to the shoreline
tombolo
a bar of sediment connecting a former island to the mainland

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