Exam 4 Flashcards
(192 cards)
1
Q
external processes
A
denudation, deposition, Fluvial, aeolian (wind), and glacial
2
Q
denudation
A
wearing away of earth’s surface leading to reduction in relief and in elevation by weathering, mass wasting, and erosion
3
Q
what do rock weathering and transport processes do to topography?
A
shapes landscapes, wears down the crust, remove and deposit material
4
Q
what does 75% of earth’s surface being sedimentary rock highlight?
A
the role of weathering, erosion, and deposition in shaping our surface
5
Q
weathering overview
A
destroys cohesion of the lithosphere
occurs via physical and chemical processes along zones of weakness rocks (entry ways for weathering agents)
6
Q
mass wasting overview
A
the short-distance downslope movement of weathered rock and soil
7
Q
Erosion overview
A
the long distance downslope movement of weathered rock and soil
8
Q
what influences weathering, mass wasting, and erosion
A
state factors
9
Q
what shapes our topography
A
landscape destabilization processes: they influence hydrological processes, and can pose natural hazard risks to human lives and economies
10
Q
weathering definition
A
disintegration and decomposition of rocks into smaller and smaller fragments by weathering agents, destroys cohesion of bedrock
11
Q
what does weathering do to rock fragments
A
mobilizes them, making them susceptible to transport
12
Q
what does weathering do to surface area
A
increase it
13
Q
how is weathering a positive feedback loop
A
increases surface area exposed to weathering agents
14
Q
what is weathered rock parent material of
A
weathered rock (either formed in place or deposited as sediment) is parent material for inorganic (mineral) component of soil
15
Q
weathering agents
A
factors that do the weathering
16
Q
atmospheric weathering agents
A
oxygen, carbon dioxide (gaseous and liquid)- carbonic acid, water (gas, solid (frost wedging), liquid (fluvial, carrying)), and resulting acids involved in chemical reactions
17
Q
Physical weathering agents
A
temperature change due to climate (temp, moisture (increase/decrease in moisture carrying capacity and moisture levels)) or heat from fire, or changes in strain due to removal of overlying rocks/sediment
18
Q
biological weathering agents
A
plants, microbes (bacteria, fungi), animals, CO2 and organic acids produced from biological activity (respiration, decomposition)
19
Q
mechanical/physical weathering process
A
physical breakdown with no changes in chemistry of the rock material
20
Q
chemical weathering process
A
breakdown by chemical alteration of minerals
21
Q
mechanical/physical weathering processes
A
frost wedging, salt wedging, thermal expansion, exfoliation, abrasion
22
Q
frost wedging
A
freeze-thaw cycles of water cause expansion of fractures and cracks in rocks, ex. frost wedging of granite in the rocky mountains
23
Q
what can frost wedging lead to
A
rockfalls in high altitudes where the climate and topography are not favorable for solid development and plant growth
24
Q
Salt wedging in arid or marine coastal environments (also known as Honeycomb weathering)
A
wetting-drying cycles and evaporation of water cause salt crystals to form and expand fractures and cracks in rocks
25
Thermal expansion due to fire (heat)
heating and cooling can cause some rocks to crack
26
exfoliation
peeling of concentric layers of rock ("onion") leads to rounded rocks and domes
ex. granite domes in yosemite
27
how are granite domes formed?
intrusive igneous rocks form underground, erosion or overlying soil and sediment releases strain and rocks expand upward and exfoliate
28
abrasion or scourning
caused by collision of pebbles, rocks transported by water, or by force of water
ex. basalt rocks in Hawaii bridge or devils lake - little scoops of rock taken by glaciers
29
chemical weathering processes
oxidation/reduction, hydrolysis, carbonation
30
when is chemical weathering more effective
- high surface area (finer grained>coarse grained)
-high moisture (humid>arid)
-high temperature (hot>cold)
31
solutions processes of chemical weathering
-water is a fundamental agent in shaping earth's surface
-H2O is a solvent for rock-forming chemicals
-underground water is a weak solution of carbonic acid (CO2 dissolved water)
-water dissolves, transports, and deposits
32
dissolution
removal of bedrock through chemical action of water
33
precipitation
coming out of solution, solidifying or crystallizing
34
oxidation (red/rusty)/ reduction
-oxidation is loss of electrons- leads to rock decomposition, weakens rock structure
-reduction is the gain of electrons
35
iron oxidation/reduction
-iron from iron-bearing minerals reacts with oxygen to form iron oxides
-releases acidity that can dissolve rock
-oxidation weakens and crumbles rocks
36
Hydrolysis
-releases acidity from dissociation of water
-dissolution of minerals from solid into dissolved from
-silicates (most abundant minerals) mostly weather though hydrolysis
37
carbonation
-releases acidity
-reaction important in limestone dissolution
-acidity increases in soil due to plants and microbial release of CO2 from respiration
38
zones of contact for weathering definition
where the weathering occurs, how rocks are exposed to weathering agents
39
zones of contact for weathering
-weathering occurs on exterior surfaces and interior of rocks
-weathering facilitated by increased surface area
40
entryways for weathering agents into rocks
microscopic openings, joints, faults, lava vesicles, solution cavities
41
microscopic openings
-very small, but reasonable for extensive weathering because numerous and occurs in all rock types (ubiquitous)
-spaces between crystals or pores between grains
42
joints
-cracks that develop in the lithosphere, but no vertical displacement of crust occurs (vs faults)
-results from contractive stress
-ubiquitous and most important ***
-often occurs as part of joint system: regular pattern can result in blocks
-scale: cm to meters
43
faults
-breaks in bedrock due to displacement lithosphere
-not as numerous as joints
-normally occur individually (vs. joint system)
-large scale: 10s- 100s of km
-lead to major landscape features
ie san Andreas fault
44
Lava vesicles
-holes that develop in igneous rocks during cooling of molten rocks
-formed by gas bubbles unable to escape during cooling
(like slime bubbles)
45
solution cavities
-holes that develop mostly in sedimentary rocks, especially in calcareous limestone
-formed by chemical dissolution reactions
-important in aquifer and groundwater storage
46
karst topography
example of a landscape shaped by chemical weathering in soluble sedimentary rock
- random square mountains
-usually bc degradation of limestone
47
what is karst topography characterized by
a chemical dissolution of rocks underground by groundwater. This dissolution destabilizes landscape surface, can lead to subsidence (collapse) (oxidation) (sinkholes)
-synonymous with carbonate bedrock
48
Mogotes/ karst towers
what remains of the limestone that was degraded, commonly formed in highly weathered, humid environments
49
Cenotes/ sinkholes
important access to groundwater for Mayan civilizations in Yucatan, Mexico
50
Biological weatheirng
Biological organisms are involved in both chemical and physical weathering
51
physical biological weathering
plant roots, burrowing animals, biological crusts, lichens (symbolic association fungi and bacteria)
52
chemical weathering
release of CO2 and organic acids produced from biological activity ( respiration, decomposition) from animals, plants, and microbes (bacteria and fungi)
53
Lichens
very effective weathering agents on recently exposed rock (moss)
54
plant roots at weathering
very effective- tree roots on a rocky side mountain can turn rock into sand
55
fossorial animals
animals that are adapted to digging and live primarily underground (earthworms, ants, moles, voles, shrews, and prairie dogs)
56
under what environmental conditions are different weathering processes most effective?
tropical forest
-tundra, Desert (hot with low precipitation), Boreal forest (hot with good precipitation), Tropical forests (hottest with highest precipitation)
57
mass wasting
short-distance, downslope movement of material driven by gravity
58
Hillslope processes (mass wasting) importance
shape landscapes and can also be natural hazards
59
Angle of repose
maximum angle, measured in degrees from the horizontal, at which loose material will remain in place without sliding
-slope threshold of steepness
-sand 33-35 degrees
-boulders as steep as 45
60
Mass wasting is characterized by
environmental conditions and speed of formation (natural hazard)
61
types of mass wasting
soil creeps, solifluction, slumps, rockfalls, landslides, flow (mudflow, earthflow)
62
soil creep
-slow, dry, short downslope movement of soil, affected by angle of slope, plant cover, moisture, and burrowing animals or grazers
-over time contributes to decreasing slope angles and lowering hilltops
-wrinkly hill, bendy trees
63
solifluction
-"soil flowage", typical in tundra landscapes
-near surface soil (above permafrost) thaws, saturated hill sags downslope
-slow, wet
-like globbed frosting dripping
64
soil slump
-larger volume of soil moves downslope
-topographic features:
--step-like terraces --bottom bulging lobe
-medium-slow, mid wet/dry
65
Rockfalls (rockslides)
-large mass of bedrock moves rapidly downslope
-common in high latitudes and high altitudes
-one of the most dangerous mass movement types
-fast, dry
-frost wedging can lead to rockfalls
66
Landslides
-occurs due to instantaneous collapse of slope and triggered by heavy rains, earthquakes, or lateral erosion by streams or road building
-flow of rocks and soil
-fast, mid dry/wet
-ex hurricane maria landslide
67
Flows
fluid movement of loose earth materials
fast, varying wet
68
Earth flows
slow moving flows og mostly fine grained or clay-rich soil/sediment
69
Debris flows
fast-moving mixture of sediment and flowing water
eg mudflows
70
Mudflows
-composed of a slurry of rocky debris, sediment and water
-moves quickly, dries into cement-like material; very dangerous
71
Lahars
mudflows triggered by volcanic eruption
eg mt st helens eruption in Washington
72
Erosion
Long-distance transport and deposition of material by water, wind, or ice
73
Fluvial processes
-fluvius: latin for river
-Erosion (valley formation, fluvial transport)
-sedimentation/ deposition
-Management effects
74
How does water move on the landscapes?
overland flow, stream flow, groundwater flow
75
Overland flow
-unchannelized flow
-Influenced by vegetation cover, rainfall intensity and duration, surface characteristics, and slope
76
Stream flow
-confined to channels, 3-D complexity
-greater capacity to erode tham overland flow because greater volume at particular time and place
-effectiveness of erosion influenced by
--speed (slope steepness and water volume) anf turbulence (determined also by roughness)
--bedrock resistance
77
components of drainage basins or watersheds
interfluves (ridge)-overland flow, valleys- stream flow
78
Mississippi drainage basin
Top Minnesota, Bottom Louisiana
79
Amazon river basin revers flow
10 million years ago due to combination of tectonic uplift of the Andes Mountains, climate, and erosion and deposition
80
what is what type of erosion
chemical and physical
81
Fluvial erosion by overland flow (interfluve)
splash erosion, sheet erosion, rill erosion, gully erosion
82
splash erosion
when raindrops hit soil, breaking up soil and dislodging particles
83
sheet erosion
when a thin layer of topsoil is removed by rain impact and shallow surface flow
-mini waterfall
84
Rill erosion
when water flows over a hilltop, cutting shallow, curvy channels into the top soil
85
gully erosion
when water flows at a velocity enough to detach and transport soil particles, creates a dich deeper than 30 cm
86
what shape of hills does water erosion create
V
87
stream flow
-water excavates banks and transports material downstream, deposits where water slows down
-Fluvial erosion within channel: physical and chemical weathering
-areas of max velocity= deepest
88
stream loads
material transported by running water
89
solution or dissolved stream loads
rock minerals, salt
highest in water column (in comparison)
90
suspended stream flows
clay, slit; slower to settle (middle)
91
bedload stream flows
sand, gravel, rock fragments, boulders (lowest)
92
Suspended sediment
seen greatest at outputs of rivers into the ocean ie mississippi and atchafalaya into gulf of mexico
93
stream flow vs bed flow
stream flow carries greater volume at any given moment, but overall flow contributes to large amounts of material transported because most of earth's land surface is interfluvial
94
how much higher is global surface area of rivers and streams than previously though
45 %
95
By what are changes in fluvial characteristics along a typical profile from headwaters to drainage affected?
steepness of slope
96
Upper river course
-young stream
--gradient: steep
-Valley: narrow
--Volume: low
--flow speed: fast
--erosion: downward -> vertical downcutting
97
Valley deepening: Knickpoints
erosion undercuts more resistant strata, migrating the erosion upstream rather than down
-ex Niagara falls recession
98
Valley lengthening
headwater erosion
high slope-faster and more powerful
99
Middle river course
Mature stream
-Gradient: low
-Valley: widens
-erosion: lateral
-volume: higher
-flow speed: slower
-meanders: some
-load: high
100
Valley widening
lateral erosion
101
lower river course
floodplain
-gradient: flat
-valley: widest
-volume: largest
-flow speed: slow
-Meanders: many
-load size: small ->deposition
102
braided streams
carry lots of sediment
103
Valley lengthening
delta formation
-provides favorable environments for humans- when we use all the soil, it replenishes, commonly by water
104
Human alterations of fluvial processes
-deforestation in watershed increases soil erosion and local sediment loads
-dams reduce sediment delivery downstream
-straightening channels to control flow
-water withdrawals reduce flows
-increase in impervious surfaces in urban areas increases runoff
-green roofs, parking lots
-buried streams
105
Human effects on magnitudes of floods
-urban watersheds; increase impervious surfaces- increased runoff and streamflow
-Rual watersheds; better land practices
106
where are deserts located?
1.) 30 deg N and S (cool, dry descending air from Hadley cells)
2.) Rainshadow or mountains
107
characteristic features of arid lands
Soils: thin or absent
texture: coarse; gravel, sand
vegetation: sparse, discontinuous cover
topography: Angular, steep slopes
weathering: physical important (but also chemical)
surfaces: impervious
rainfall: intense
fluvial deposition: ephemeral streams
basins: interior drainage
108
Desert pavement
impervious/impermeable surfaces of compacted sand
109
most important externally-driven shaper of landscapes in arid climates
fluvial erosion
110
fluvial erosion in aridlands
when it rains, it pours
111
common landform types in the U.S. arid lands
Basin-and-range terrain, Mesa-and-scarp terrain
112
Basin-and-range terrain
-mountain ranges of variable diastrophic origin: faulting, folding, volcanism
-interior drainage basins (from playas and salinas)
-ex death valley (sup hot)
range= mountain range basin =lull
-igneous and metamorphic rocks
113
Mesa-and-scarp terrain
-more common in sedimentary rocks
-differential erosion very important
-ex bryce canyon and badlands
mesa= table, flat scarp= trough
-sedimentary rocks
114
Horst and Graben
formed by normal faults horst-up garben-down
115
gully erosion in the ranges
delivers material to the basins
116
alluvial fan
fan of sediment at the bottom of the range-into the basin- deposited by streams
117
Interior drainage basin
playa
118
salina
accumulation of salt where ET>P
119
special Mesa-and-scarp terrain
differential erosion (jums between scarp and inclined slope depending on sediment strength)
120
mesa-and-scarp terrain: landscape features shaped by differential weathering and erosion
resistant dikes: igneous intrusive rock squeezed through sedimentary rocks
Pinnacles: weathering along joint systems ex badlands, UT
121
Aeolian
from the greek god of wind Aeolus
122
Wind erosion
abrasion and deflation
123
wind abrasion can amplify
valley lengthening
124
Loess
wind-blown silt
125
Brady soil
paleosol rich in carbon that was formed about 15,500 to 13,500 yrs ago and then buried by wind-blown loess
126
transport across oceans
dust from arid lands in china bring phosphorus to subsidize tropical forest growth in highly-weathered soils in Hawaii
127
aeolian transport across oceans
dust from Sahara brings nutrients (calcium and phosphorus) to caribbean and South American forests
128
Dust storms
health and visibility hazard
129
piedmont
from the french for foot of the mountain
130
pluvial
from the latin pluvialis, rain (ex., pluvial lakes are filled by rainwater)
131
pebbles of mars
possible evidence of physical weathering (abrasion) via fluvial transport
132
Glacial-Interglacial cycles
-global cooling trend 50-60 million years
-cycles driven by variation in earth's orbit around sun though time (Milankovitch cycles)
133
Glacial-Interglacial cycles result in
different amount and distribution of solar energy
-these variations affect growth and melting of ice sheets
134
Pleistocene Ice age
geologic epoch that included the last Ice Ages (2.8 MYA to about 11,000 yrs ago ot 11 KYA)
135
Last glacial maximum (LGM)
(most recent) maximum glacial ice cover worldwide, 21 KYA- ice covered 1/3 earth's land surface
136
Earth's climate oscillation
between cool and warm periods
137
Earth's recent climate history
-last 2 million yrs (quaternary): progressive cooling and cycles of glaciation/deglaciation
-past 10 KY: Holocene (interglacial) (name of period)
-current anthropogenic climate change: rate of change unprecedented
138
how do ice sheets grow?
cold summers
139
how do ice sheets retreat?
warm summers
140
Glaciar formation
accumulated snow metamorphism into different ice layers
snow->Granular ice->Firn->glacial ice
141
last deglaciation
21 ka to present
142
Ice cover today
-10% earth's surface
-only two continental glaciers remain: Greenland and Antarctica
143
types of glaciers
continental ice sheets, mountain glaciers
144
continental ice sheets
-formed in non mountainous regions at high latitudes
-most significant agents of glaciation because of vast size
-only two remain: Antarctica and Greenland
145
Mountain glaciers
-also known as alpine glaciers
-form at high elevations
-in North America, most are in Alaska and Pacific NW
146
Direct effects of glacial movement
-physical weathering (abrasion and plucking)
-Very effective erosion
-long-distance transport of material: 100s of kms
-heterogeneous load size
147
deposition of direct glacial movement
till and drift
148
till
directly deposited by glaciers- unsorted, unconsolidated material of different sizes
149
drift
deposited by meltwater
150
deformation
movement of glaciers under their own weight
151
flowing
movement of glaciers by meltwater
152
Evidence of glacial abrasion on rock surfaces
striations and grooves
153
U-shaped valleys
Alpine glaciers as effective agents of erosion in mountains
154
physical weathering by alpine glaciers
frost-wedging
155
comparison of fluvial vs. glacial erosion
-fluvial erosion in mountains leads to v-shaped deep valleys vs U-shaped wide valleys by glacial erosion
-streams from glacial meltwater have greater flow when temperatures rise, not associated with precipitation (seasonal differences)
-Material deposited by glaciers tends to be more heterogeneous in size and unsorted
-fluvial loads tend to be deposited by size as finer material is transported longer distances
156
Glacial transport
-glaciers weather rock by abrasion and plucking
-glaciers transport eroded material as they flow over landscape (soils, rock) or from valley walls (for alpine glaciers)
-debris carried on surface of glacier, buried within the ise, or underneath the glacier
157
erratic boulder
boulders deposited by retreating glaciers ("erratic" because do not match local geology, instead transported long distances by glaciers)
158
Topographic features after glaciers retreat
Moraines, drumlins, kettle lakes
159
Moraines
landforms composed of till deposits "terminal moraines"
160
Drumlins
low oval mound or small hill formed from glacial till
161
outwash
sediment and landforms created by meltwater of glaciers
162
kettle lakes
when a block of glacier ice gets lodged and them melts
163
the great lakes
formed by retreating glacial abrasion
164
indirect effects of glaciation (periglacial) def
beyond the outermost edge or margin of glaciers, effects on regions not directly covered by ice
165
indirect effects of glaciation
-isotonic rebound
-solifluction
-fluvial erosion and transport from melting water
-Pluvial lakes
-changes in sea level
166
Glacial isotonic rebound
earth's crust adjusting to the lack of glacial weight
ie sweden and finland rising (causing Denmark to sink)
167
Mass wasting: solifluction
gradual movement of soil down a slope due to freeze-thaw cycles- lobes
168
Fluvial erosion
meltwater has greater flows in midsummer from melting ice
169
Pluvial or pleistocene lakes
lake with considerable fluctuation in volume
-bodies of water that accumulated in a basin because of a greater moisture availability resulting from changes in temperature and/or precipitation
170
changes in sea level
lowered 120 m
171
Short- and long-term effects of glaciers melting in northeastern Tibetan plateau
-the largest glacier in the 800-km (500-mi) Qilian mountain chain has retreated about 450 m and lost 13 m (42 ft) thickness since the 1950s
-increased flooding in spring and summer shortages when irrigation is needed
172
glacier meltwater flowing atop glaciers
creates bumpy pattern
173
the world is warming
Global Mean Temperatures have risen since 1900 and accelerated sive 1970s
174
rise in global mean temperatures 1880-2012
0.85 degrees C (1.53 degrees F)
175
Why is the world warming
green house effect is getting stronger
176
global warming science
1. Fossil fuel burning and land use ->
2. Greater concentrations of greenhouse gases
(CO2, CH4, N2O) in atmosphere ->
3. Strengthened greenhouse effect ->
4. Less longwave radiation escaping to space ->
5. More energy staying in earth system
(unbalanced Energy budget) ->
6. Greater temperatures at Earth’s surface ->
7. Ice melt, sea level rise, changes in rainfall, etc.
177
what are fossil fuels
hydrocarbons created by photosynthesis 100's of millions of yrs ago
178
burning fossil fuels releases
energy (which we use) and greenhouse gasses (a problem)
179
Trends in CO2, CH4, N2O since 0AD
reamiing stable, until exponentially increasing around the industrial revolution
180
ice core records of greenhouse gasses
segmenting ice cores from glaciers and melting them reveals atmospheric components of the related time periods- providing records
181
what did Vostok ice core record of 400,00+ years find
Co2 and temperature track each other
182
early signs of climate change
-increase in temperature
-increase in sea level
-decrease in snow cover, glacier extent
183
where do 40% of the population live
in coastal areas that may be vulnerable to sea level rise
184
historical observations of ice seasonality
-records of lake Suwa in Japan (1442-) show later ice formation- may be oldest human observation of climate change
-Shinto priests recorded ice freeze dates
-Ancient legend described ice ridge as god's footsteps crossing the lake
185
historical observations of ice seasonality pt 2
River ice breakup dates in Finland (1693-) show earlier breakup
-greater changes post-industrial revolution
186
lake trends
freeze later, melt sooner
187
warmer winters increae
drowning risk
-fatalities from drowning are 5x higher in warmer weather
-increased risk of ice instability later in winter season with climate change
188
why do we see most rapid warming at high latitudes
the shoulder of earth
189
positive feedback loop of warming
surface temps increase->reduction of snow cover->decreases reflection sunlight back to space
190
temp of permafrost is
increasing
191
permafrost thaw is a new source of
CO2 and CH4
-it is frozen organic material with low oxygen levels
-creates a positive feedback to warming
192
why study earth surface processes
-Foundation for other disciplines: biogeography,
ecology, soil science, agronomy, engineering,
anthropology, economics, political science, history…
o To improve management of natural resources
o To understand risk of natural hazards and improve
emergency preparedness and response
o To better understand earth’s past and predict future
o To appreciate our surrounding environment
Why study earth surface processes?
