GEOG 120 FINAL Flashcards
(145 cards)
1
Q
What is the difference between weather and climate?
A
Weather is the state of atmosphere at a specific place and time on earths surface
Climate is the long term average values of weather elements such as temperature and precipitation
2
Q
What are climate normals
A
Climate trends established for periods of 30 years
3
Q
What 5 variables influence climate?
A
Latitude, Seasonality, Air mass circulation, Maritime vs continental, topography
4
Q
Are temperatures warmer over large continents than adjacent oceans?
A
yes
5
Q
What is the difference between airmasses that affect north America in the summer vs winter?
A
cT - tropical airmass only in summer, cA and cP polar airmasses are smaller
6
Q
What are the two kinds of climate classification?
A
Genetic classification - climate classification based on causative factors, like the interaction of airmasses
Empirical classification - based on statistical data such as air temp and precip
7
Q
What 3 variables does the Koppen climate classification use?
A
Avg monthly temp
Avg precip
total annual precip
8
Q
6 major climate groups in KCC?
A
- A - Tropical (tropical latitudes: no winter season)
- C - Mesothermal (midlatitudes, mild winter)
- D - Microthermal (mid and high latitudes, cold winters)
- E - Polar (high latitudes and polar regions)
- H - Highland (high elevations at all latitudes)
- B - Dry (permanent moisture deficits at all latitudes)
9
Q
Two points about dry B climates?
A
- Orographic lifting intercepts moisture-bearing weather systems to create rain shadows along mountain ranges that extend these dry regions into higher latitudes.
- Dry climates are subdivided into deserts and steppes. Both have permanent water shortages, but deserts have greater moisture deficits than steppes.
10
Q
Three mechanisms of natural climate fluctuation?
A
- Continental position and topography
- atmospheric gasses and aerosols associated with volcanic activity
- earths orbital cycles
11
Q
3 Milankovitch cycles
A
Orbital Eccentricity - variation in the shape of Earth’s orbit influences amounts
insolation; 90,000-100,000 year cycle
- Tilt Obliquity - variations in Earth’s axial tilt increases or decreases seasonal
contrasts in insolation; 40,000 year cycle - Orbital precession - cyclical change in the wobble of the earth on its axis influences seasonal extremes at perihelion and aphelion; 23,000 year cycle
12
Q
When did the earth form?
A
4.6bya
13
Q
What are the two broad earth systems?
A
Endogenic system - internal processes like plate tectonics, earthquakes, and volcanos that produce flows of heat and material from below crust, radioactive energy is the main energy source
Exogenic system involves external processes that set into motion air water and ice (wind rivers and glaciers) all powered by solar energy
14
Q
What is the earths core?
A
Inner + outer core
Inner core is solid iron and nickel - 3200-5200degc above the melting temp but remains solid due to pressure
outer core is molten - flow generates magnetic field
15
Q
What is the earths mantle?
A
Lower and upper mantle - 1300c and pressure
Iron and Magnesium
rocks in upper mantle are molten and flow
Boundary between the uppermost mantle and the crust is called the mohorovicic discontinuity
16
Q
What is the asthenosphere?
A
uppermost mantle layer of molten rock capable of flowing
40-250km
17
Q
What is the lithosphere?
A
layer of crust and uppermost mantle, flow of materials initiates movement of lithospheric plates
18
Q
Continental vs oceanic crust
A
Continental crust - 30km thick beneath continents, higher under mountains
silica, aluminium, potassium, sodium, calcium
composted mainly of granite and gneiss
Oceanic crust - 5km thick beneath ocean
silica magnesium iron
composed mainly of basalt and gabbro
19
Q
What is buoyancy in the context of the crust?
A
something less dense floats in something more dense, crust floats on denser layers of mantle
where crust load is higher under glaciers or mountains crust sinks into asthenosphere
20
Q
What is isostasy?
A
isostatic rebound - movement of the crust
- entire crust is in constant state of adjustment bc of floating up and down
21
Q
What is the Kola superdeep borehole?
A
12000m deep, took 20 years, abandoned bc too hot
22
Q
How do we know wtf is deep in the earth if we haven’t been there?
A
studying seismic waves and earthquakes
23
Q
Difference between minerals and rocks, 3 types of rocks?
A
Mineral - inorganic natural compound having a specific chemical formula and a crystalline structure
Rock - assemblage of minerals bound together or to other materials
- Igneous - fire formed, molten
- Sedimentary - from settling out
- Metamorphic - altered
24
Q
What are the two most common elements in the crust?
A
Oxygen and silicon
25
What are silicate minerals?
from from silicon and oxygen, make up 90% of earths crust
forms primary minerals during cooling of magma
26
What are igneous rocks?
- derived from molten rock, magma
* magma emerges on Earth’s surface as lava associated with volcanic eruptions
* magma intrudes and cools within crustal rocks; intrusive igneous rocks (e.g., granite)
* slow cooling produces coarse-grained rocks
* magma is erupted as lava and cools on Earth’s surface; extrusive igneous rocks (e.g., basalt)
* rapid cooling produces fine-grained or glassy rock
-mineral composition of igneous rocks; based on the relative contribution of SiO2
* felsic rocks: high %SiO2 – quartz, feldspar - light-coloured minerals; dominate continental crust
➢aluminosilicate minerals
* mafic rocks: low %SiO2 – mica, amphibole, pyroxene – dark-coloured minerals; dominate oceanic crust
➢ferromagnesian minerals
27
What are sedimentary rocks?
begin as the products of rock weathering (clastic sediments), accumulations of calcareous materials (chemical sediments), accumulations of organic matter
(organic sediments)
* erosion, transport and deposition of sediments
* lithification – compaction, cementation
* both clastic and chemical sedimentary rocks are deposited in layers – strata – that record the environmental history of a region
28
What are chemically precipitated sedimentary rocks?
formed of thick deposits of mineral compounds that accumulate in marine environments or evaporate from solutions
- limestone forms as calcium carbonate from either marine organisms or carbonate precipitation, cements into thick deposits
- dolomite is a carbonate rock that contains abundant magnesium
- evaporites form in continental locations when minerals evaporate from concentrated solutions
29
What are organic sedimentary rocks?
Consist of carbon-based materials that accumulate in thick deposits at the surface and then get buried by other sediments
- coal results when the carbon deposits are very slowly compacted, removing water and oxygen, and lithified
- petroleum results when organic deposits are heated so much that they liquefy
- natural gas comes from the remains of microscopic plants that lived in the ocean
* when they died they sank to the bottom of the ocean to decompose, forming gas
30
What are metamorphic rocks?
igneous and sedimentary rocks are transformed by heating and great pressure to form metamorphic rocks
* rocks become harder and more resistant to erosion
* metamorphism may involve creation of new minerals and/or changes in mineral arrangement
* distinguish between foliated (e.g., gneiss) and non- foliated rocks (e.g., quartzite, marble)
31
What is the principle of superposition?
Rock and sediment are always arranged with the youngest materials “superposed” toward the top of a rock formation and the oldest materials at the base, if they have not been disturbed; relative age
32
who is the father of plate tectonics or continental drift?
Wegener
33
What is plate tectonics?
the theory that the lithosphere is divided into a number of plates that float independently over the mantle and along whose boundaries occur the formation of new crust, the building of mountains, and the seismic activity that causes earthquakes.
*plate tectonic theory describes the motion of Earth’s lithospheric plates.
34
What are passive margins?
In plate tectonics where continental crust and bordering oceanic crust are
actually on the same tectonic plate and do not move relative to each other
* not geologically active – seismic activity but no active volcanism
35
What are divergent boundaries in plate tectonics?
divergent boundaries occur in areas of seafloor spreading, where upwelling material from the mantle forms new seafloor and lithospheric plates spread apart in a
constructional process.
Most occur at mid ocean ridges but some occur in continents - great rift valley of east africa
36
What are convergent boundaries in plate tectonics?
convergent boundaries occur in areas of crustal collision and subduction, where areas of continental and oceanic lithosphere meet, crust is compressed and then lost in a destructional process as it moves downward into the mantle. - ocean-continent collisions
* convergent boundaries form subduction zones, such as off the west coast of South and Central America, along the Aleutian Island trenches, and along the east coast of Japan.
* convergent boundaries also occur where two plates of continental crust collide, such as the collision zone between India and Asia, and where oceanic plates collide, such as along the deep trenches in the western Pacific Ocean.
- similar low densities so neither one sinks, instead they compress and fold and fault
37
What are transform boundaries in plate tectonics?
Occur where plates slide past eachother horizontally
as they move past they form a type of fault in the crust called a transform fault
- powerful seismic activity
38
What are volcanoes?
* a mountain or a large hill containing a conduit that extends down into the upper mantle, through which magma and gases are periodically ejected onto Earth’s surface or into the atmosphere
- magma erupted onto the surface is referred to as lava
* most volcanoes are inactive for some time and only erupt when the pressure of the rising mantle material becomes excessive
39
What are explosive volcanoes and what are they known as?
Composite volcanoes
- Build up over several eruptions
- magma is rich in silica which traps gasses and builds up pressure
- sends volcanic ash and pyroclastic material into air
- composed of lava and pyroclastic sediments
- characterized by steep slopes and small surface area
40
What are effusive volcanoes and what are they known as?
Shield volcanoes
- fluid eruptions
- far less silica, lower viscosity
- lava flows as rivers of molten rock
- have gently sloping sides
- develop with successive eruptions that gradually build up over a large area
41
What are volcanic island arcs?
chains of volcanoes that occur at converging or subducting plate boundaries
42
What is hot spot volcanism?
Area of volcanic activity associated with a stationary zone of an upwelling mantle plume from the asthenosphere
- occurs randomly under continental and oceanic crust
- lithospheric plates move over stationary hotspots
- plate movement can be traced by the evidence of volcanic activity
43
What is a seamount chain
A string of islands left after being positioned over a hotspot - Hawaii
44
What is geomorphology?
the science of landforms including the origin, form, evolution, and spatial distribution
45
What are endogenic processes?
Contribute to the creation of landscapes of high topographic relief, mountains, volcanoes etc
46
What are exogenic processes?
Contribute to development of landscapes with low topographic relief, plains, sedimentary platforms
47
What is orogenesis?
mountain building
48
What is denudation?
Set of processes that transform materials at earths surface
- lowering surface of the continents
- physical and chemical weathering - creates sediments and minerals
- erosion, transportation and deposition - create erosional and depositional landforms
- gravity, running water, wind, waves, ice
49
What are the two kinds of weathering?
Physical / mechanical weathering - rocks disintegrating without chemicals
Chemical weathering - decomposition due to chemical reactions - ALWAYS in the presence of water
50
5 factors influencing weathering
rock comp and structure
- climate
- subsurface water
-slope orientation - facing away from sun means more vegetation
- vegetation - plant acid and roots break rocks
51
do faults and joins increase weathering?
yes, joints are fractures in rock that occur without displacement
52
3 physical weathering processes
- frost wedging - freeze thaw - when water freezes its volume expands, repeated freeze and thaw can break rocks
- salt crystal growth - crystallization - forms due to moisture, crystals enlarge due to water absorption called hydration - mineral grains are released from rock - granular disintegration
- pressure release jointing - exfoliation - removes overlying rock (pressure release - rocks respond via isostatic uplift (dilation) - expansion results in fracturing to create pressure release jointing
- joints define boundaries of sheet rock - creates exfoliation zones
53
5 chemical weathering processes
- solution - evaporite minerals - dissolving simple salts in water
- hydrolysis - alumnosilicate minerals - decomposition due to water
- hydration - evaporite minerals - water becomes a part of the chemical composition of the mineral
- carbonation - limestone - addition of carbon
- oxidation - oxygen from water added to minerals, breaks
54
What are karst landscapes?
regions of limestone or gypsum bedrock characterized by surface depressions (dolines) and well developed solution channels underground caverns created by chemical weathering
- cover 15% of surface
55
What is regolith?
bedrock that has been weathered and transformed, forms parent material of soils
56
What is colluvium?
regolith or soil moving on hills due to gravity
57
4 types of mass movement
Creep - slow process occurring everywhere, under gravity and freeze thaw slowly move downhill
Slide - sudden movement of mass of regolith that is not saturated with moisture - landslide, two forms translational slides and rotational slides (slumps)
Fall - release of rock from a steep slope
Flow - when regolith is saturated with water flows occur, mudflows, earthflow, debrisflow
58
What are talus cones?
deposits of fallen rock
cones or aprons (many cones)
59
3 components of avalanches?
Starting zone - steep slopes
Track - where it goes
Runout - where it runs out of energy and stops
60
2 stream flow regimes
perennial streams - flow year round
- effluent conditions - water table is above the stream surface
- stream flow is supported by base flow throughout the year
ephemeral streams - contain water for a short time
- influent conditions - water table is below streambed
61
on hillslopes how does water move/
sheetflow
62
what are drainage divides?
define the boundaries of drainage basins, control movement of water into stream channels
drainage basins are separated by continental divides
63
four points about drainage basins and watersheds
Within a drainage basin runoff and groundwater flow into streams that funnel into the largest stream called the trunk stream
- each stream flowing into trunk stream is a tributary
- tributaries are separated by interfluves
- point where tributary joins trunk is a confluence
64
How do you calculate drainage density?
= total length of stream channels / area of basin
generally humid climates have low drainage and arid climates have high drainage denisty
65
What is the gradient of a stream?
drop in elevation per unit distance
a river has a steeper slope near the headwaters and a more gradual slope downstream
66
What is the base level of a stream>
level below which a stream cannot erode its valley, ultimate base level is sea level
67
4 variables of hydraulic geometery?
focuses on the morphology of stream channels
-W = channel width
-d = channel depth
-v = velocity of water
-s = slope/gradient
68
What is stream discharge Q
- amount of streamflow volume passing a point in a given unit time
- Q = w x d x v
- generally increases downstream - effluent condition
69
What is alluvium?
the general term for unconsolidated clay sily sand and gravel deposited by running water
70
What is hydraulic action?
stress applied by flowing water to bed and banks of stream channel
71
What is abrasion?
sediment particles loosened and detached by hydraulic action mechanically erode the stream channel
72
What is corrosion?
chemical weathering within the stream channel releases material into solution
73
What is the Hjulstrom-Sundborg diagram?
diagram depicting what happens to particles based on velocity and particle size
- either transported eroded or deposited
74
2 forms of erosion on hillslopes?
Rainsplash - raindrop impact on soil breaks down aggregates reducing rate of infiltration of water
Sheet erosion - precip is stored temporarily in surface depressions then begins to flow downhill as sheetflow
forms rills and gullies (big rills)
75
3 types of load ins streams?
dissolved - chemical weathering
suspended - fine grain particles
bedload - coarse grained materials
76
What happens when the discharge of a stream varies?
increase in discharge (Q) leads to an increase in erosion and
transport
– stream capacity – total load of material that can be
transported at a given Q
– stream competence – largest particle that can be
transported at a given Q
* decrease in discharge leads to a decrease in transport and
eventually deposition of sediment
77
2 responses of stream channels to floods
Channel degradation associated with erosin
Channel aggradation associated with deposition
78
4 points on channel patterns?
- multiple-thread channels, either braided or anabranching
* single-thread channels are either straight or meandering
* straight and braided channels tend to occur in headwater areas where gradient and/or sediment load is high.
* in lower-gradient areas with finer sediments, meandering or anabranching channels are more common.
79
Conditions associated with braided stream channels
Conditions associated with braided channel formation
include:
* an abundant supply of coarse sediment
* steep stream gradient
* rapid and frequent variations in water discharge
* erodible banks
Channel aggradation associated with development of sand
and gravel bars that give rise to the multi-thread channel
form.
80
Conditions associated with meandering stream channels
Conditions associated with meandering channel formation
include:
* an abundant supply of fine sediment
* gentle stream gradient
* cohesive banks
Characteristic landforms:
* pools, cutbanks – erosional
* point bars, levees – depositional
* oxbow lakes
81
What are river deltas?
* the mouth of a river is where the river reaches a base level.
* river’s velocity rapidly decelerates as it enters a larger, standing body of water.
* reduced stream energy causes deposition of the sediment load.
* coarse sand is deposited closest to the river’s mouth.
* finer materials, such as silt and clay, are carried farther and form the extreme end of the deposit.
- the nearly depositional plain that forms at the mouth of a river is named for the traingle shape it forms
82
What is the cryosphere?
portions of the hydrosphere that are always frozen
- 3/4 of freshwater is frozen
- generally found at high latitudes and altitudes
- extend is variable
83
What is a glacier and how do they develop?
a glacier is a slowly moving mass of dense ice formed by the gradual thickening, compaction, and refreezing of snow and water over time
* develop in regions where heavy snows fall in winter and then do not melt completely during the subsequent summer
– summer temperatures must be sufficiently cool
at high latitudes and high altitudes cold temperatures may allow snow to remain on the ground year-round
* glaciers form by continual accumulation of snow above the snowline, followed by compaction, melting and refreezing that compresses air space within snow pack
* snow that persists throughout the summer and into the following winter becomes firn
* ongoing compaction, melting and refreezing slowly transforms firn into glacial ice
snowflakes - compression for a month - granular snow - firn (compression for a year) - glacial ice after 4 years
84
Points on alpine and continental glaciers
masses of glacial confined within alpine valleys
- cirque glaciers
- valley glaciers
- piedmont glaciers
* tidewater glaciers terminate in the sea; characterized by
calving of icebergs
* ice sheets and ice caps are large masses of ice that inundate
land surfaces and result in isostatic depression of the
crust
* may terminate in the sea, forming ice shelves
85
How is glacier mass balanced?
Glaciers are open systems
Accumulation processes - snowfall, freezing, deposition of water
- dominates at higher elevations - positive mass balance
Ablation processes - melting, calving of icebergs, sublimation
- dominates at lower elevation - negative mass balance
the firn line represents the boundary between accumulation and ablation zones
86
How do glaciers move?
glacial ice experiences internal deformation in response to stress: the mass of ice, especially in the accumulation zone, and slope angle affect stress
* rate of internal deformation is related to ice temperature: ‘warm’ ice flows more rapidly than ‘cold’ ice
* movement of ‘warm’ ice is assisted by presence of meltwater beneath glacier; serves to lubricate the bed – basal slip
flow across uneven bedrock surfaces results in variations in ice thickness and ice pressure on the bed
* glacier thickens on convex surface, resulting in melting of ice at base of glacier – basal slip
* glacier thins on concave surface, resulting in refreezing of meltwater – regelation
* regelation at base of glacier contributes to erosion of rock - plucking
* variations in forward motion of glacier – faster over concave surfaces, slower over convex surfaces – create crevasses
87
2 kinds of glacial erosion?
plucking - stress applied by glacier against the bed overcomes the strength of rocks releasing large angular rock clasts
abrasion - rock clasts in transport at bed of glacier are used to cut into and or polish the rock surface producing striations
roches moutonnees are combination of plucking and abrasion
88
What is a fjord?
glacial troughs that have been flooded during post glacial sea rise
89
2 kinds of glacial depositon?
deposition occurs when glacier is no longer able to transport debris – lodgement and melt-out
* lodgement occurs in response to an increase in ice pressure applied to debris moving in the subglacial environment
* melt-out occurs in response to supply of geothermal heat in the subglacial environment and solar radiation in the supraglacial environment
* deposits unsorted, unstratified debris known as glacial
drift or till
90
How is a moraine formed?
forms at the margins of glaciers and not glaciers
- form when ice margin is stationary for a long time
- composed of melt out tills
91
Hummocky moraine and kettle lakes?
* deposition of till by melt-out over top of stagnant glacial ice at the glacier margin
* subsequent melt-out of buried glacial ice creates hummocky topography
* depressions in the till surface are filled with water to form kettle lakes
92
What is glaciofluvial deposition?
- meltwater flowing beneath glaciers that transport sediements
- deposition of sediments from flowing water produces glaciofluvial outwash
- depositional landforms include eskers, kame, and outwash plains
- during deposition sediements are sorted according to grain size - coarsest sediements deposited first, creates well sorted stratified drift
93
What is an esker?
type of glaciofluvial deposition
- alluvium deposited in contact with glacier ice creates long narrow ridges of stratified gravel and sand
94
What is an outwash plain/
deposition of coarse grained alluvium in braided channels
95
What are periglacial landscapes?
landscapes around perimeter of glaciers
96
What is permafrost?
soil or rock temp always frozen for atleast 2 years, includes
- present fossil permafrost from previous ice age conditions
- the insulating effects of snow cover or vegetation that inhibit heat loss
permafrost regions are divided into two zones - continuous and discontinuous zones, discontinuous permafrost is colder
97
What is talik?
unfrozen ground that may occur above below or within a body of discontinuous permafrost or beneath a water body in the discontinuous zone
98
what is the active layer?
zone of seasonally thawed ground that exists between permafrost and ground
- thickness increases with decreasing latitude due to warmer climates
99
three factors that determine distribution of arid regions?
- dominance of subtropical high pressure systems with descending masses of ait like hadley cells
- rain shadow effects on leeward side of mountains
- distance from large water bodies - rlly continental means less moisture
100
3 types of arid desert landscapes?
- erg - mainly sand dunes
- reg- mainly pebbles and cobbles
- hamada - largely exposed rocky outcrops and rocky plateaus
101
What are aeolian processes?
Processes due to the work of the wind, erosion, transportation and depositions
- most active in arid regions due to dry conditions and large supply of sand and silt
102
Moving particles via wind
silt and clay are difficult to erodue due to cohesion - they are lifted and moved together
- sand and gravel are easy to erode because no cohesion - easy to detach via hydraulic action - moved via saltation or roll along surface via creep
103
What is aeolian abrasion?
sandblasting
- rocks exposed appear pitted - ventifacts
- yardangs are large scale structures formed by abrasion
104
4 types of aeolian depositional landforms
ripples, dunes, ergs and desert pavements
105
How are sand dunes classified?
based on sand supply, amount of vegetation and wind speed
based on shape - crescentric, linear, star
formation is dependant on wind and topography, sand must accumulate and then is shaped by flow
106
3 components of active sand dunes
backslope - windward surface where erosion and saltation dominate
- crest - highest point of the dune marking the boundary between erosion and deposition
- slip face is the portion of the dune where deposition occurs
107
What are loess deposits?
glacial outwash deposits that were transported and deflated by wind and deposited as unstratified homogenous deposits
108
brine vs brackish water
brine has more than 35%0 salinity
brackish is less
(ppt)
109
What do wave shore interactions depend on?
shape of coastline
direction of winds
wave heights
nature of coastal sediements
110
4 littoral processes for sediment transport
longshore current - flows parallel to the shore and forms when waves approach the shore at an oblique angle
longshore drift - movement of sediment by the longshore current
beach drift - transport of sediment on the beach face
littoral drift - transport of sediment from the combined action of longshore and beach drift
111
What is wave refraction and what does it do?
* wave refraction takes place as waves slow in shallow water and pivot around headlands
* concentrates wave energy on headlands; vigorous erosion occurs here
* sediments generated by headland erosion are transported by littoral drift and deposited in bays to form pocket beaches
112
Coastal Landforms: Erosional Coastlines
* erosion of rocky headlands creates wave-cut notches, sea stacks, and wave-cut bluffs at the shore; contribute the retreat (retrogradation) of the coastline
* in the nearshore environment, sediment transport results in abrasion of the rocky seabed, creating a wave-cut platform
113
Coastal Landforms: Depositional Coastlines
progradation refers the outward extension of the shoreline through
deposition of sediment, e.g. deposition of deltas at the mouths of rivers
beaches are dynamic places where sediment is deposited by beach drift
and wind
- represent a transition between the water and the coast; consist of
unconsolidated sediments that range from sand to cobbles
* beach growth occurs in summer in Northern Hemisphere when weather is relatively calm
* beach erosion occurs in winter in Northern Hemisphere due to large waves created by strong winds
114
5 beach components
Beach components based on their position to water:
- offshore occurs below wave base
- offshore bar is a submerged ridge; zone where waves break
- foreshore is influenced by rise and fall of sea-level (e.g., tides)
- berm is ridge formed at the high water line of the beach
- backshore is a relatively flat part of the beach that is covered with
water only during severe storms; source of sand for dunes
115
how do coastal dunes and foredunes develop?
* coastal dunes develop because of the abundant supply of sand from adjacent beaches
* a foredune develops where shore vegetation traps sand blown by the
wind off the beach and gradually forms a linear dune
* transgressive dune fields form where the supply of sand is especially
large and the winds are consistently strong
- these dunes advance inland (transgress) from the beach
- vigorous deflation may create blowout dunes
116
What determines the distribution of vegetation and what does this result in?
climate is the biggest factor
- results in biomes - forest, grassland, desert, tundra
117
What is an ecotone?
transitional area between biomes
118
Points on forest biomes?
* geographic regions where vegetation is dominated by trees
* occur in areas where a net surplus of available moisture occurs,
due either to high average annual precipitation or low average
temperatures that keep evaporation low
* are found across a large latitudinal range and are categorized into
three broad biome types:
– Tropical forest
– Midlatitude forest
– Boreal forest
Midlatitude Broadleaf and Mixed Forest
* broadleaf trees that form a closed canopy
* in eastern Canada, maple, beech and oak are common
* deciduous with seasonal leaf fall
* mixed with needleleaf (coniferous) trees such as pine, fir and hemlock further north
Midlatitude Coniferous Forest
* consist largely of needleleaf evergreen trees
* in mountainous areas in North America, Douglas fir, Ponderosa pine, and lodgepole pine are common
* on west coast of North America, Douglas fir and Giant redwoods are common
* In southeastern USA, longleaf pine is common
* tree species are adapted to forest fires
Boreal Forest
* distributed widely in subarctic of North America and Russia
* associated with permafrost
* dominated by needleleaf evergreen trees including spruce, pine and fir;
includes deciduous needleleaf trees such as tamarack (larch)
* may include small stands of deciduous broadleaf trees such as birch, poplar, and aspen
* transitions to an open canopy woodland farther north
119
Points on grassland biomes
Midlatitude Grassland/Steppe
* associated with regions located far from moisture sources (continental
interiors) or located in rain shadows of mountain ranges
* dominated by perennial grasses; woody vegetation is sparse
* tall grasses in humid areas, short grass in more arid areas
* plants are fire-adapted
* forms an ecotone with the Midlatitude Broadleaf Forest (i.e. parklands in Saskatchewan)
120
Points on desert biomes
Semi-Arid and Cold Desert
* cool temperatures, and low to no surplus moisture
* distributed widely in western North America and Asia
* dominated by short grass and drought-adapted shrubs (e.g. sagebrush) with patches of bare ground
121
Points on tundra biomes
Tundra Vegetation
* located in high latitudes in North America and Russia
* also occurs in high altitude environments
* associated with permafrost
* dominated by stunted shrubs, grasses, sedges, mosses, and lichens
* forms an ecotone with Boreal Forest
122
Influences on biogeography - slope
slope is the degree of steepness to an are
- as slope increase so does surface runoff
- slope aspect is the cardinal direction of a slope
- insolation intensity depends on slope aspect
- adret slopes face into the sun
- ubac slopes face away from the sun
123
Influences on biogeography - vertical zonation
refers to changes in the vegetation present with increasing elevation
- air temp decreases as altitude increases
- treeline is the elevation or latitude above which conditions are too harsh for trees
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Influences on biogeography - plant succession
* plant succession refers to the natural changes that occur in a biome over time
* sequence of changes in the vegetation cover is usually predictable for a given area
- primary succession begins with pioneering species colonizing bare sediments
- over time, a progressive increase in diversity as plants and animals move into the area
- finally, a vegetation community exhibiting complex structure develops - climax vegetation
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What is soil?
uppermost layer of surface containing mineral and organic matter that is capable of supporting plants
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3 soil forming processes
- bioturbation - mixing by biota
- wetting (swelling) and drying (shrinkage)
- frost action - cryoturbation
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5 factors determining soil development
climate, organisms, topographic relief, parent material, time
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Soil-Forming Factors: Climate
Temperature and moisture influence the type and rate of
biological and chemical reactions in soil
– warm, humid regions have better developed soils than cold, dry regions
– moisture dramatically influences the process of
translocation
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Soil-Forming Factors: Organisms
organisms add organic materials
- transform organic materials
- roots and burrows for water and gas exchange
- contribute to translocation of materials
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Soil-Forming Factors: Relief
- differences in elevation in a landscape
- soils are thin and poor on steep slopes - more erosion takes place
- soils can develop more fully on level slopes
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Soil-Forming Factors: Parent Material
- regolith consist of products of mechanical and chemical weathering of rock
- residual parent material is created as underlying rock weathers
- transported parent material has been moved from where it was created
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What are soil horizons?
Distinct layers in a soil profile
* O organic material
* A mixture of humus and mineral grains
* Ae mineral grains - quartz, feldspar (eluviated layer)
* B enriched in clay or organic colloids, Fe/Al oxides (illuviated layer)
* C weathered rock: parent material
* R unweathered bedrock
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What is the Canadian system of soil classification?
genetic system - relationship to the environmental setting
- based upon physical properties of soil
adapted for cool climates - unique soil development due to permafrost
- for recently developed soils
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What are regosolic soils?
- associated with recently deposited alluvium
- thin Ah horizon
- no B horizon
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What are brunisolic soils?
- soils that develop under mixed forest cover
- well to imperfectly drained
- dark Ah horizon, brown Bm
- medium fertility
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What are podzolic soils?
- soils under coniferous forest
- well drained
- coarse grained parent material
- Ah, Ae, Bh, Bf horizons
- acidic pH, low fertility
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What are luvisolic soils?
- develop under mixed forest cover
- well drained
- fine grained parent material
- Ah, Ae, Bt horizons
- high fertility
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What are gleysolic soils?
- high ground water table - saturated
- thick Ah horizon
- poorly drained
- gleied horizon Bg (grey or blue)
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What are organic soils?
- composed of organic matter
- poorly drained gleied horizons
- high water capacity
- ph more than 5, fen
-ph less than 5, bog
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What are chernozemic soils?
- grassland soils
- well drained
- high organic matter content
- thick Ah
- Bt enriched in clay
- Cca - carbonate deposition
- high fertility
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What are vertisolic soils?
- grassland soils
- imperfectly drained
- parent material rich in swelling clay
- thick Ah
- B horizon, soil shrinks when dry swells when wet
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What are cryosolic soils?
- permafrost at surface
- Cz - permafrost horizon
- poorly drained gleied horizons
- above permafrost layer cytoturbation mixes soil in active layer
- By - cryoturbation
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What are solonetzic soils?
- grassland soils
- imperfectly drained
- saline parent materials
- low organic content
- Bnt horizon, columnar structure
- Csa horizon - salt pan
- low fertility
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What is soil salinization?
Soil salinization is the accumulation of soluble salts in soil
and can occur under natural conditions associated with
topographic depressions (e.g., hummocky moraines)
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What are the 5 real soil forming processes?
1 addition of new organic material
2 transformation of organic material into hummus by decay
3 translocation of dissolved minerals by elluviation
4 accumulation of elluviated materials by illuviation
5 mixing bio or cryo turbation
