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Geography Test 3


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Periglacial environments
envornment where freeze-thaw cycles modify the landscape
1)Arctic and Subarctic=not alot of flux in temp day and night but High flux in temp during seasonal changes
2) Alpine= alot of seasonal and daily fluxation in temp.
frozen layer of soil or sediment not a prerequiste.
Types of Permaforst
1) continuous- High Altitude
2) Discontinous- edge of high altitude
3) Sporadic- Localized spots
4) Alpine - in the mountains
5) Subsea- under water
localized unfrozen layer
1) closed- a layer of unfrozen material completely sourrounded by permafrost in every direction
2) open- layer of unfrozen material completely sourround by permaforst on all sides expect the side to the surface
Physical Weathering of Periglacials
Freezing/thawing cylces which cause:
1)ice wedging
2)Thermal expansion
3) rockfalls
4) Periglacial spree and talus
Pore Ice
water in pore spaces freezing
Needle ice
Long slivers of ice
Ice wedges
occur on large scales and can be meters wide and deep. they wedge soil and permafrost material apart.
Segregated Ice
water is channeled to an area that creates a layer of ice. The water flowing to this just adds to the ice
Frost Heaving
occurs when soil expands and contracts due to thawing
Soil creep
slow downhill movement of near-surface soil over small distances
when the upper layer of permaforst thaws out a mass movement of saturated soil moves downslope
Process where fallen snow gets converted to ice. Its a group process associated with snow packs. The edges of the snow packs have freezing and thawing which causes the material to break up
Sand Dunes and Loess
occur at the edge of glaciers.
Loess is a fine grained deposit of silt and clay
Pattern ground
the result of freeze thaw activity, Hexagonal in appearence
ice is under pressure and is pushed up because of ice lense, creating mounds
1) closed- continous flow
2) open: discontinous flow
associated with bog like environments, smaller than pingos
cryoplanation terraces
1) rise steeply
2) little soil developement
3) tread: soil material accumulates here
4) resembles benches carved into hill slopes
Landforms associated with the melting of ground ice, could create lakes or ponds
Dry vs. Wet permafrost soils
1) dry soils remain frozen and stay in place
1) wet soils creep
Organic Mats
often a thick organic mat ontop of permafrost
process that lifts coarse material up to the surface
a system of flowing or moving ice
Valley glacier
found in canyons or mountains
Outlet glacier
flow through mountain passes
Continental Glaciers
Large areas of ice covering large areas. Ex. Greenland and Antartica
Ice Caps
glaciers but smaller in size
Snow to ice conversion
1) snow falls and accumulates
2) Snow is then compacted
3) Distortion/recrystalization: firn or neve which is the snow is hard, it melts and then hardens again
4) Thus glacial ice
Zone of Accumulation in a Glacier
1) Dry Zone: found in the interior of the region of the glacial ice sheets.
2) Percolation Zone: some meltwater percolates into the depths of the glacier, where it freezes, or it flows down the glacier where it might refreeze
3) wet zone: all seasonal snow melts in this zone
Zone of Ablation
occurs when the summer lose of snow, through melting, sublimation or evaporation exceeds the amount of snowfall recieved in the winter, this can be identified by an expanse of bare ice
irregular boundary between ablation and accumulation
Glacial budget
1) positive- if gain is more than loss
2) negative- if loss is more than gain
3) balanced- glacier is neither advanceing or receding
Glacial Flow
the top part moves the fastest
solid state flow
1) rotation of grains loose granuals that can move past each other
2) freeze thaw- material can melt and flow somewhere, and refreeze
3) Internal slipping- different levels of ice are forming and forming on top of each other, these layers can slip and slide along each other
Basal sliding
glacier so heaving that the top pressures the bottom into melting creating a lubricant and it slides
Extending and compression Flow
Extending- steep slopes
compression- gentle slopes
Glacial surge
rapid movement of the glacier: basal water jacks up the glacier and causes it to slide very fast
Ice falls
when ice falls from the glacier
a fissure or crack that is formed due to a change in the glacial speed
1) Marginal- outside the glacier
2) Transverse- cross the glacier and are perpendicular to the flow
3) Longitudinal- where the lobes break out, parallel to flow
4) radial- cracks that radiate out from a certain point
loose rock fragments that the glacier picks up as it moves, freezes into the glacier
the frozen fragments at the bottom of the glacier erode the bedrock beneath the glacier
flat edges that are angled or cut into bedrock by a glacier
scratches or gouges cut into the bedrock during the process of glacial abrasion
rock flour
silt or clay size particle created by the glacier
U-shaped valleys
glaciers cut a U-shaped valley
hanging valley
results from trubutary glaciers leading into larger ones.
Lateral Moraine
the accumulation of till deposited along the margins of a glacial valley. It accumulates as a result of the mass movement of debris on the sides of the glacier
Medial Moraine
material pushed together by two glaciers on either side of it
Ground Moraine
Debris on the ground
Terminal Moraine
the debris at the head of an advancing glacier
Recessional Moraine
when the glacier recedes and stops along the way, multiple terminal moraines are left behind
Gravel, sand, and silt deposited by the melt water as it flows from glacial ice
tear dropped shaped hill formed by the deposits of glacial till
a long narrow ridge of sand and gravel deposited by glacial melt waters
a water filled pit created by blocks of ice from glaciers after the glacier retreated
mounds of sediment that are small hills. They are formed by a stream intersecting a crevasse in which the sediment from the stream is dumped, over time as the sediment builds up and glacier abates the sediment collapses into a hill
Pleistocene Glaciation and its effects
1) drainage of our rivers, at one point the rivers flowed toward the northeast
2) created lakes
3) glaciers influenced wind patterns: glaciers increased wind velocity due to the cold air
4) ocean water became isotopically heavy
5) biological changes
Glacials Vs. Interglacials
1) extremely cold, artic climate
1) occur between glacial epochs
2) a comparatively warm time during an overall period of glaciation
Europes mountains are East-West which means less biodiversity
North Americas mountains are North-South which means more biodiversity
Milankovitch Cycles
Eccentricity (100,000 years)
1) earths orbit changed from more to less orbital and visa versa
Obliquity (40,000)
1) the tilt of the earth changes
Precession (20,000)
1) the earth wobbles on its axis
Plate Tectonics
Formation of mountains alters the earths climate by disturbance of airflow and they provide a perfect home for glaciers
Atmospheric Compression
increases in CO2 and methane, which makes the earth warmer
Ocean currents
plays a role in glaciation, ocean conveyor belt
Quaternary Period
Pleistocene Epoch is the oldest
Holocene Epoch is the most recent
Characteristics of Deserts
1) lack through-flowing streams
2) many have internal drainage and many are basins
3) flash flooding and streams with a distint appearence
4) Angular topography because of lack of vegetation and lack of rain
Atmospheric Subsidence
caused by cold temp. the density of the cold air causes the atmosphere to sink
an area far from sea that has higher seasonal variation which makes deserts more likely
found on the leeward side of a mountain
cold ocean currents
found in the west coast, these currents hold less moisture in the air causing deserts
silt and clay carried by the wind
sand that the wind picks up and then drops
mass of sand that slowly moves due to gravitation
wind transports material by blowing it away
Deflation basins
hollows formed by the removal of particles by wind
lag deposits
accumulation of coarse, unconsolidated rocka and mineral debris left behind by the winnowing of finer material
desert pavement
the desert surface that is covered with closely packed interlocking angular or rounded rock fragements of pebble and cobble size. Thought to be caused by wind and rain carrying of all the smaller material
Pebble armor
desert armor made up of round pebbles
Desert Abrasion
natures sand blasting, sand removes rock material by blasting against it
stone that has been shaped by wind driven sand
little mounds that are parallel to windflow
a highland area that consists of relatively flat open country
elevated area of land with a flat top
and isolated hill with steep sides and a small top
the geological term used to describe the ridges formed by gently tilted hard rock layers, unequal slopes
equal sides
tall thin spires of rock that portrude from the bottom of arid basins and badlands, they are composed of soft sed. rock and are topped with a hard piece of stone that protects it from the elements
an isolated hill, knob, ridge, or small mountain that rises abuptly from a gently sloping or virtually level surrounding plain
Horst Topography
A raised block of the earths crust that has remained stationary while the land around it has sunk or has been crushed by a mountain range against it
Graben topography
a depressed block of land which is the result of a block of land being downthrown producing a valley with a distinct scarp on each side
alluvial fans
fan shaped deposit
usually dry creek bed that fills when heavy rain
a convergence of alluvial fans into a single apron deposits against a slope
a flat surface that occurs at the base of a mountain, formed primarily by erosion
small round depressions in the surface
playa lakes
formed when lakes fill the playas
Sand sheets
flat deposits of sand
sand ripples
ripples perpendicular to wind
sand dunes
hill of sand built by wind
eolian process
wind shadow
area behind an obstacle where wind is not capable of moving material
cross bedding
sets of inclined layers or beds, typically found in dunes
Transverse Dunes
wave-like dunes, long winding dunes, most common
Barchan dunes
cresent like dunes tips point down wind
Linear Dunes
longer than they are wide, form sets of parallel ridges
Star Dunes
have three or more arms
Parabolic Dunes
cresent like but tips point upwind
Chihuahuan Desert
Located in Mexico and some parts of US
Sonoran Desert
strattles the US-Mexican border
Great Basin
Between the Sierra Nevada mountains and the rockies, has no outlet to ocean
Mojave Desert
Southern Cal. SW Utah, S Nevada, and N Arizona
degradation of land in arid and dry areas resulting from various factors like climate variation and human activities, caused by increased human demands
fine grained accumulation of clay and silt deposited by wind
wave height
crest to trough
wave length
crest to crest or trough to trough
top of wave
bottom of wave
wave period
time between wave crests
wave base
1/2 wavelength below surface
surf and breakers
as wave approaches bottom it will begin to feel shallow bottom, decrease in wavelength and speed increase in height. Breakers are collapsing waves
up beach flow of water
down beach flow of water
wave refraction
change in angle of wave to one that is more parallel to the shoreline
wave diffraction
change in direction of wave because of an obsticle
tidal bore
tides with a pronounced wave front
Neap tides
weak tides
spring tides
strong tides
perigean/proxigean tides
unusually high tides
Long shore currents
how sediment moves down beach. Parallel to shoreline
long shore drift
step by step advance of sediment because waves comin in at angles
zone of beach where the tides are going to cover and uncover it
beach face
steepest part of foreshore
back shore
upper part of beach above high water line
finger like ridge of sediment
baymouth bar
ridge of sediment that closes a bay
ridge of sediment from mainland to island
barrier islands
narrow ridge of sand parallel to mainland
rock wall to protect harbors, perpendicular to coast
rock wall to protect beaches perp. rows of rock that jut out from coust
offshore structure to block waves , parallel to shore
shoreline equalibrium
a balance between landfroms and geological processes operating on them
Emergent vs. Submergent Coasts
Emergent coast are uplift and exposure of marine terraces due to plate tectonics while submergent are sea level rise
convergence coasts
two plates collide create subduction: deep water and large waves
Passive-margin coasts
plate tectonics is weak: flat low gradient
marginal coasts
protected by island arcs
Types of reefs
1)fringing: attached
2)barrier: not attached
3)platform: isolated, oval
4)atolls: oval, surrounded by lagoon
storm surge
winds pushing water up coast combined with low pressure bulge
Geological resources
sometimes called mineral resources: energy, metals, and nonmetalic resources
1) Oil: crude oil is liquid hydrocarbons
2) Natural gas: gaseous hydrocarbons
source rock
rock that has organic matter that can be converted into oil or gas due to increases in temp.
reservoir rock
porous and permeable rock
conditions that hold petroleum in place
Environmental effects of oil recovery
1) pipeline leaks
2) tanker spills
3) offshore platform blowouts
4) subsidence- something has to fill the space we empty
5) air pollution and human health
resources vs. reserves
resources is the total amount of geologic materials in all deposits, discovered and undiscovered. Resources are the discovered deposits that can be economically and legally extracted
USGS estimates
oil: 1000 gigabarrels 50 years
gas: 170 trillion cubic meters 70 years
use increasing
liguid coal
types of coal
1)Peat: some vegetation
2)Lignite: more carbon more layers
3)Subbituminous and Bituminous: normal coal
4)Anthracite: hard to light
coal reserves
275 billion tons 200 years most in the western (whyomming)
It is essential for life and plays a role in the evolution of most features of the landscape. 78% nitrogen 21% oxygen and minor amounts of other gases like carbon dioxide and water vapor
total mass of water on the surface of the planet, covers 71% of the earth's surface and 98% of all water on the earth comes from the oceans.
Part of the earth where life exists
is the outermost compositional layer. The crust of the continents is different then the crust of the ocean basins.
the layer that surrounds or covers the core, constitutes the great bulk of the Earth. composed of silicate rock
The central mass of the earth. Mostly metallic iron. it has two properties, an outer core which is in liquid form and an inner core which is solid
The outer most part of the earth's crust.
extensive flat region of a continent, in which complexly deformed ancient crystalline rocks are exposed.
Basement Complex
rocks in the shield that are highly deformed igneous and metamorphic rock.
stable platforms
when a basement complex is covered with a veneer of sedimentary rock. An example is the area between the Appalachian Mountains and the Rocky Mountains.
Mountain Belt
a long linear zone in the Earths crust where the rocks have been intensely deformed by horizontal stress during the slow collision between two plates.
Oceanic Ridge
It is essentially a broad fractured rise in the ocean floor.
Rift Valley
a huge cracklike valley that runs along the axis of the oceanic ridge throughout much of its length.
Fracture System
system of fractures that run perpendicular to the oceanic ridge
Abyssal Floor
Area of broad relatively smooth deep-ocean basins that run on both sides of the oceanic ridge.
Abyssal Hills
relatively small ridges or hills, rising above the surrounding ocean floor.
Abyssal Plains
Land-derived sediment that completely covers the abyssal hills that form flat smooth plains
Lowest areas on the earth's surface.
Isolated peaks of submarine volcanoes
Continental Margins
the zone of transition between continent and ocean basin
Continental Shelf
submerged part of the continent
Continental Slope
It marks the end of the continental rock mass
Plate Tectonic theory
The earth's crust is forming and deforming due to the moving and colliding of the earth's plates
Divergent Plates
Are where the plates move apart at divergent plate boundaries, which causes a gap where mantle swells up and then solidifies creating midoceanic ridges
Transform Plates
Occur when plates horizontally slide past one another.
Convergent Plates
Are when two plates move towards each other. Subduction occurs which is when one plate slides beneath the other one.
smallest fraction of an element that can exist and still show the characteristics of that element.
electrically charged atoms
Characteristics of crystals
natural elements or inorganic compounds in a solid state
Crystal Form
is a reflection of the internal structure and is an identifying characteristic for many mineral specimens.
is the tendency of a crystalline substance to split or break along smooth planes parralel to zones of weak bonding in the crystal structure.
is the measure of a mineral's resistance to abrasion, measures the strength of the atomic bonds in a crystal
is the ratio of the weight of a substance to its volume
Most obvious but not always consistant, most minerals have varying hues
describes the appearence of light reflected from a minerals surface
The color of a mineral in powder form, more diagnostic than color
Natural characteristic found in some minerals
Most abundant Earth Elements
Oxygen, Silicon, Aluminum, Iron, Calcium, Sodium, Potassium, Magnesium
Felsic Minerals
large group of silicate minerals, include feldspars and quartz which constituent major part of the continental crust.
most abundant mineral in granite, most abundant mineral in the earth's crust, are common in most igneaous rock
grows in spaces between other minerals, abundant in all three major rock types.
abundant in granites and many metamorphic rocks.
Mafic Minerals
Minerals that contain magnesium and iron, often found in ocean crust. Crystallized at higher temperatures and higher densities than felsic
Found in the upper mantle
single chains, found in the crust and mantle
Double chains, common in igneous rocks and metamorphic rocks
Non-silicate minerals
Form at low temperatures and pressures
principle mineral in limestone
results from the chemical reaction b/w calcium carbonate and magnesium when water flows over, found in Sedimentary rocks
salts, Halite and gypsum
Ore Minerals
lack silicates, include oxides, sulfides, native elements like gold and silver
molten rock material, when cools forms igneous rock. Two types: Basaltic(very hot, 900c to 1200c) and Silica typically cooler.
Intrusive rock
cooled magma under the surface
Extrusive rock
cooled magma above the surface
various gases in magma trapped in bubbles, causes eruptions
rapid cooling
does not allow for crystals to form
slow cooling
crystals form easier
Pyroclastic materials
Ash, Pumice, Tephra, and Tuff
Basaltic Eruptions
Most common type of volcanic activity, lava is extruded from fractures or fissures in the crust
Cinder cone
cone shaped hill composed of loose volcanic fragments erupted from a central vent
a large more less circular depression or bassin associated with a volcanic vent
shield volcanoe
occurr when a number of thin basaltic lava flows errupt from a central vent or fissure
composite/strata volcanoes
occurr when alternating layers of tephra and thick viscous lava flows or domes creating a high steep-sided cone centered around a vent.
are masses of intrussive igneous rock of any size
is a small pluton with an outcrop area of less than 100km2
large exposures of intrusive rock
narrow, tabular body of igneous rock, form when magma enters a fracture and cools
Volcanic neck
forms when magma soldifies in a pipe-like conduit through which lava reaches the surface
occurs when magma is injected into a bedding plane which seperates layers of sedimentary rock
an ingneous intrusion that has arched up.
Sedimentary Rocks
Form from fragments derived from other rocks and by percipitation from water.
mechanical breakdowns and chemical decay of prexisting rocks create sediment, which is then compacted and cemented to form solid rock.
Clastic sedimentary rocks
Sedimentary rocks formed from fragments of other rocks
consolidated deposits of gravel (fragments larger than 2mm in diameter)
Most familiar, constits of mostly quartz, calcite, and iron oxide
Fine-grained clastic rocks, most abundant sedimentary rock
Biochemical/Chemical Sedimentary Rocks
from when chemical processes remove ions dissolved in water to make solid particles
most abundent chemically precipitated rock, composed mainly of calcium carbonate
show the changes that occur during the forming of sedimentary rock
Graded Bedding
stratification that shows a progressive decrease in grain size upward through the bed
ripple marks
seem in stream beds
mud cracks
show that the sedimentary environment was exposed to air during deposition
Depesitionaly environment
Where the sediment is deposited. Include rivers, desert dunes, glaciers
Sea advance
sea retreat
Metamorphic Rocks
form by recrystallization in the sold state because of changes in temperature, pressure, or the composition of pore fluids. Result largely from the constant motion of tectonic plates
Metamorphic parent material
Igneous, sedimentary, or even metamorphosed rocks
Hydrothermal alteration
Hot gases alter the shape of the rock
metamorphic recrystallization is often accompanied by some change in the chemical composition of the rock-loss or gain of certain elements
confining pressure on metamorphic rocks
thrust sheets are stalked at convergent plate boundaries which creates pressure and causes mineral changes
low-grade metamorphism
metamorphism that takes place at low temperatures and pressure
high-grade metamorphism
metamorphism that takes place at high temperatures and presssure

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