Geography Test 3
Terms
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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. - Permaforst
- 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 - Taliks
-
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
- Solifluctuation
- when the upper layer of permaforst thaws out a mass movement of saturated soil moves downslope
- Nivation
- 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
- Pingos
-
ice is under pressure and is pushed up because of ice lense, creating mounds
1) closed- continous flow
2) open: discontinous flow - Palsas
- 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 - Thermokrats
- Landforms associated with the melting of ground ice, could create lakes or ponds
- Dry vs. Wet permafrost soils
-
Dry:
1) dry soils remain frozen and stay in place
Wet:
1) wet soils creep - Organic Mats
- often a thick organic mat ontop of permafrost
- Cryoturbation
- process that lifts coarse material up to the surface
- Glacier
- 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
- Snowline
- 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
- Crevasses
-
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 - Plucking
- loose rock fragments that the glacier picks up as it moves, freezes into the glacier
- Abrasion
- the frozen fragments at the bottom of the glacier erode the bedrock beneath the glacier
- facets
- flat edges that are angled or cut into bedrock by a glacier
- Striations
- 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
- Outwash
- Gravel, sand, and silt deposited by the melt water as it flows from glacial ice
- Drumlins
- tear dropped shaped hill formed by the deposits of glacial till
- esker
- a long narrow ridge of sand and gravel deposited by glacial melt waters
- Kettles
- a water filled pit created by blocks of ice from glaciers after the glacier retreated
- Kames
- 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
-
Glacials:
1) extremely cold, artic climate
Interglacials:
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
- Continentality
- an area far from sea that has higher seasonal variation which makes deserts more likely
- rainshadows
- 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
- Suspension
- silt and clay carried by the wind
- Saltation
- sand that the wind picks up and then drops
- creep
- mass of sand that slowly moves due to gravitation
- Deflation
- 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
- Ventifacts
- stone that has been shaped by wind driven sand
- Yardangs
- little mounds that are parallel to windflow
- Plateau
- a highland area that consists of relatively flat open country
- Mesa
- elevated area of land with a flat top
- buttes
- and isolated hill with steep sides and a small top
- cuestas
- the geological term used to describe the ridges formed by gently tilted hard rock layers, unequal slopes
- Hogbacks
- equal sides
- hoodoos
- 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
- Inselburgs
- 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
- arroyos
- usually dry creek bed that fills when heavy rain
- bajadas
- a convergence of alluvial fans into a single apron deposits against a slope
- pediments
- a flat surface that occurs at the base of a mountain, formed primarily by erosion
- playa
- 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
- 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
- Desertification
- degradation of land in arid and dry areas resulting from various factors like climate variation and human activities, caused by increased human demands
- Loess
- fine grained accumulation of clay and silt deposited by wind
- wave height
- crest to trough
- wave length
- crest to crest or trough to trough
- crest
- top of wave
- trough
- 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
- swash
- up beach flow of water
- backwash
- 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
- foreshore
- 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
- spit
- finger like ridge of sediment
- baymouth bar
- ridge of sediment that closes a bay
- tombolo
- ridge of sediment from mainland to island
- barrier islands
- narrow ridge of sand parallel to mainland
- jetties
- rock wall to protect harbors, perpendicular to coast
- groins
- rock wall to protect beaches perp. rows of rock that jut out from coust
- breakwater
- 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
- Petroleum
-
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
- trap
- 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 - coal
- use increasing
- slurry
- 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)
- Atmosphere
- 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
- Hydrosphere
- 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.
- Biosphere
- Part of the earth where life exists
- Crust
- is the outermost compositional layer. The crust of the continents is different then the crust of the ocean basins.
- Mantle
- the layer that surrounds or covers the core, constitutes the great bulk of the Earth. composed of silicate rock
- Core
- 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
- Lithosphere
- The outer most part of the earth's crust.
- Shields
- 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
- Trenches
- Lowest areas on the earth's surface.
- Seamounts
- 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.
- Atom
- smallest fraction of an element that can exist and still show the characteristics of that element.
- Ions
- 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.
- Cleavage
- is the tendency of a crystalline substance to split or break along smooth planes parralel to zones of weak bonding in the crystal structure.
- Hardness
- is the measure of a mineral's resistance to abrasion, measures the strength of the atomic bonds in a crystal
- Density
- is the ratio of the weight of a substance to its volume
- color
- Most obvious but not always consistant, most minerals have varying hues
- Luster
- describes the appearence of light reflected from a minerals surface
- streak
- The color of a mineral in powder form, more diagnostic than color
- Magnetism
- 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.
- Feldspars
- most abundant mineral in granite, most abundant mineral in the earth's crust, are common in most igneaous rock
- Quartz
- grows in spaces between other minerals, abundant in all three major rock types.
- Mica
- 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
- olivine
- Found in the upper mantle
- Pyroxenes
- single chains, found in the crust and mantle
- Amphiboles
- Double chains, common in igneous rocks and metamorphic rocks
- Non-silicate minerals
- Form at low temperatures and pressures
- Calcite
- principle mineral in limestone
- Dolomite
- results from the chemical reaction b/w calcium carbonate and magnesium when water flows over, found in Sedimentary rocks
- Evaporites
- salts, Halite and gypsum
- Ore Minerals
- lack silicates, include oxides, sulfides, native elements like gold and silver
- magma
- 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
- Volatiles
- 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
- caldera
- 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.
- Plutons
- are masses of intrussive igneous rock of any size
- stock
- is a small pluton with an outcrop area of less than 100km2
- batholiths
- large exposures of intrusive rock
- Dike
- 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
- Sill
- occurs when magma is injected into a bedding plane which seperates layers of sedimentary rock
- Laccolith
- an ingneous intrusion that has arched up.
- Sedimentary Rocks
- Form from fragments derived from other rocks and by percipitation from water.
- Sediments
- 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
- Conglomerate
- consolidated deposits of gravel (fragments larger than 2mm in diameter)
- Sandstone
- Most familiar, constits of mostly quartz, calcite, and iron oxide
- Mudrocks
- 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
- Limestone
- most abundent chemically precipitated rock, composed mainly of calcium carbonate
- Stratification
- 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
- transgresion
- Sea advance
- Regression
- 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
- Metasomatism
- 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