Exam 3 Flashcards
1
Q
physical weathering
A
rocks are fractured and broken apart
2
Q
chemical weathering
A
- minerals that make up rocks are chemically altered or
dissolved. The end products are often softer and bulkier forms that are more susceptible to erosion and mass movement.
3
Q
Frost action (or freeze/thaw)
A
- physical weathering processes in cold climates. Action of water expansion upon freezing
- causes joint-block separation
- Water invades sedimentary rocks along bedding planes
- Joints cut bedding planes at right angles, and action creates the joint blocks
4
Q
Salt-Crystal Growth
A
- In arid climates, slow evaporation of groundwater
from outcropping sandstone surfaces - Crystal growth breaks the rock apart, grain by grain, producing niches, shallow caves, and rock arches
- physical weathering
5
Q
Exfoliation
A
- rock layers crack as the pressure of overlying rocks is reduced by erosion
- physical weathering
6
Q
Thermal Action
A
- Thermal action cracks rocks when temperature changes cause minerals to expand and contract at different rates
- Physical weathering
7
Q
Principal forms of chemical weathering (all include the presence of H2O)
A
1) hydrolysis
2) oxidation-reduction
3) carbonation
8
Q
Karst
A
terrain produced by the chemical dissolution of limestone (carbonation).
To form:
• formation must contain high CaCO content
• pattern of joints in impermeable limestone is needed to focus water
• need aeration zones underground
• need vegetation that provides organic acids
9
Q
regolith
A
Slopes are mantled with regolith (parent material of “soil”), which accumulates at the foot of slopes as colluvium
10
Q
alluvium
A
Regolith that is transported by moving water
11
Q
Mass wasting
A
- spontaneous movement of soil, regolith, and rock under
the influence of gravity
12
Q
Forms of mass wasting depends on:
A
- speed of the motion
- amount of water involved
13
Q
Angle of repose
A
- Refers to loose, unconsolidated materials (gravel, sand, soil, etc.). The angle of repose is the angle at which loose material sits at rest. Typically 25 - 40 degrees.
14
Q
soil creep
A
Slow movement of soil under the influence of gravity, sign of unstable ground
15
Q
Mudflow
A
Fast movement of heavily saturated fine earth (clays and silt), acts like a fluid
16
Q
Earthflow
A
Fast movement of heavily saturated fine earth (clays and
silt), acts like a fluid (but less fast and less wet than a mudflow)
17
Q
rockfall
A
Fast movement of rock (typically considered “dry” movement)
18
Q
debris avalanche
A
Fast movement of fine earth, larger rocks, and boulders (has some water saturation)
19
Q
slump-rotational slide
A
Slow “rotational” movement of intact blocks of earth.
20
Q
translational slide
A
Slow linear slide of intact blocks of earth.
21
Q
solifluction
A
Movement of wet soil over frozen ground (permafrost)
22
Q
Erosional Landforms (smallest to largest)
A
- rills
- gullies
- ravines
- canyons
23
Q
Rills
A
begin with small channels or rivulets of water following a gravitational path downslope
24
Q
gullies
A
Deforestation on these mountain slopes near Katmandu, Nepal, has led to rapid erosion and gullying
25
potholes
Abrasion by stones on a bedrock riverbed can dig deep depressions
26
two elements needed for potholes
- turbulent water
| - tools (sediment/rocks)
27
Cut bank
area of erosion (not addition) where active stream erodes part of the bank.
28
Point bar deposit
alluvium accumulated on the inside (low energy) portion of a growing meander curve.
29
longitudinal
| profile
a depiction of the down slope gradient of a stream.
30
Stream Gradation
Streams can develop a more-or-less stable state, in which its long-term capacity to transport sediment is matched by the long-term rate at which it receives sediment, known as a graded stream.
31
Evolution of Stream Valleys
1) Downcutting produces canyons and gorges
2) Stream becomes graded and begins to build a floodplain
3) River moves freely from one side of the valley to the other
4) Floodplain and alluvial meanders form
32
plateau
forms when flat-lying rocks are eroded in an arid climate and successive rock layers are stripped or washed away (such as the American southwest)
33
Playas
dry lake, typically high salt content from evaporation
34
Pediments
gently sloping erosion surface of low relief formed by running water (alluvium cover) at the base of a receding mountain front
35
Pluvial Lakes
ancient lakes that were once much larger due to different climates
36
hydraulic action
Streambeds and banks are eroded by hydraulic action (power of falling water), abrasion, and corrosion
37
Thalweg
point of fastest flow
38
mesas and buttes
Erosion by wind and water creates plateaus, mesas (bigger), and buttes (smaller) from resistant rock layers
39
Waves are driven by
wind
40
Wave height is related to
* Wind speed
* Duration
* Fetch (distance traveled)
41
Wave crests
high point of the wave
42
wave trough
low point of the wave
43
Wave height
vertical distance between trough and crest
44
Wave length
horizontal distance from trough to trough or from crest to crest
45
orbit
is the same diameter as the wave height and decreases with depth
46
wave circulation
As wave crest passes, particles move forward on the wave crest, downward as the crest passes, backward in
trough, and upward as the next crest approaches
47
Break
when the height exceeds vertical stability
48
Beach drift
Swash approaches shore at oblique angle. Backwash
flows back along the most direct downhill direction. Sand particles move to one side of the starting point many times, transporting particles long distances along the shore.
49
Longshore drift
waves approach a shoreline at an angle to beach,
| creating current parallel to the shore – longshore current. Current is capable of carrying sand along the sea bottom.
50
Littoral drift
beach drift and longshore drift together move particles in the same direction for a given set of onshore winds
51
Straight or long curved shoreline
littoral drift moves the sand along the beach in one direction
52
Bay feature
– sand is carried out into open water as a long finger, or sandspit, that may form a barrier, called a bar, across the mouth of the bay
53
Wave Refraction
When a wave approaches a coastline of cliffs, its energy is concentrated at the headlands. Sediment is eroded from cliffs on the headland and carried by littoral drift along the sides of the bay. The sand is deposited at the head of the bay, forming a pocket beach.
54
flood tides
Every day coastal regions experience two high tides
55
ebb tides
Every day coastal regions experience two low tides
56
spring tide
moon and sun aligned. gravitation pulled outward
57
neap tide
sun and moon form triangle with earth. gravitation pulled out from top and bottom
58
East Coast (Passive Boundary)
– no tectonic activity
– sediment from rivers on the continent accumulates over millions of years, provide
materials to build the coastal plain, beaches, and islands
– coastal landform characteristics are depositional—built by sediment moved by waves and currents
59
West Coast (Active Boundary)
– high amount of tectonic activity
– rocks rise from the sea along subduction boundaries and transform faults
– landform characteristics are erosional, with waves and weathering slowly eroding the strong rock exposed at the shoreline
60
erosional coastal landforms
```
notch
cave
shore platform
arch
stacks
clif
```
61
Beach (Depositional Coastal Landforms)
a wedge
| -shaped sedimentary deposit, usually of sand, built and worked by wave action
62
Foredunes (Depositional Coastal Landforms)
narrow belt of dunes that form from ample sand in the region landward of beaches
- protective barrier from waves
63
barrier spit (Depositional Coastal Landforms)
dune in ocean connected to land on one side
64
barrier islands (Depositional Coastal Landforms)
dunes in middle of ocean
65
Tombolo (Depositional Coastal Landforms)
level of a strip of sand between higher earth
66
Coral reefs
Large colonies of coral and algae.
67
coral and algae relationship
symbiotic (they cannot survive without each other)
68
Fringing Reefs
platforms attached to shore, widest in front of headlands where the wave attack is strongest
69
Barrier reefs
offshore, separated from the mainland by a lagoon. Narrow gaps at intervals
70
Atolls
– circular coral reefs enclosing a lagoon with no land inside. Most are rings of coral growing on top of old, sunken volcanoes (seamounts).
71
coral bleaching
- coral eject algae
- bleaching = reef dying
- natural process but occurring at unprecedented rates because polution
72
Eolian (or Aeolian) erosion
wind erosion and leads to deflation (removal of lighter particles around heavier ones) and abrasion (grinding of rock surfaces through ‘sandblasting’)
73
Desert pavement
fragments ranging in size from pebbles to small boulders concentrated into a surface layer due to rain, overland flow, and deflation removing fine particles.
74
Desert pavement (hypothesises)
H1: Wind deflation can produce blowouts and help form desert pavement, a surface armor of coarse particles that minimizes further deflation. (blow away sand until all that is left is rocks)
H2: fine particles and rainwater work to uplift, or displace larger clasts which make the pavement.
75
geoglyphs
Stone alignments or land pictures
76
Barchan dune
a crescent -shaped heap of sand that moves across a flat, pebble -covered plain. Points of the crescent are directed
downwind.
77
Parabolic dunes
are often found where shorelines provide a large sand
| supply. long and scale like. points are directed upwind
78
Transverse dunes
formed when there is so much sand that it completely covers the solid ground. Wave-like ridges separated by trough-like furrows. Crests are at right angles to the wind direction
79
Longitudinal dunes
long, low sand ridges parallel to the prevailing wind direction.
80
ventifact
Wind abrasion can carve stones on a desert plain into shapes with flattened or grooved sides
81
yardangs
In some types of layered rocks, wind abrasion can produce tongue- or teardrop-shaped ridges oriented parallel to the prevailing wind direction.
82
Loess
Deposit of wind-blown silt
| - has excellent cohesion and often develops vertical faces as it wastes away or is removed to build road banks.
83
Alpine glaciers
(mountain glaciers) are found in high mountain ranges
| where snow accumulates and temperatures are cold enough to maintain year-round snow cover
84
Cirque Glacier
Occupies a steep, bowlshaped depression near a mountain
summit. This glacier, has shrunk in the present warm interglacial climate and would have been much larger during the last glacial period.
85
Valley Glacier
Valley glaciers flow down steep-sided valleys once carved by streams. Several glaciers have coalesced into this valley glacier in Saint Elias National Park and Preserve, Alaska.
86
Tidewater Glacier
A glacier that ends in a valley filled by an arm of the sea. They often produce icebergs that break off and float away.
87
Piedmont Glacier
A mountain glacier that flows out of the mountains and
| onto a surrounding lowland.
88
Ice Sheet (Continental Glacier)
large thick plate of glacial ice moving outward in all directions from a central region of accumulation lowland
- thickest at the center
89
glacier movement
- Glaciers are very dynamic and move as a result of tremendous pressure, temperature, and gravity. Usually less than 1 m a year.
- Does not move all at once, variable rates of torque, freeze and thaw, and motion
90
crevasses
cracks in a glacier
91
Moraines
are piles of debris and sediment that accumulate at the
| front or sides of a glacier
92
Eskers, drumlins, kettles, and kames
landforms of till and outwash plains left by ice sheets.
93
zone of
| accumulation
top of slope. gaining glacier. flows towards ablation
94
zone of ablation
bottom of slope. losing glacier
95
Formation of Glaciers
The mass balance of a glacier depends on snow input in the zone of accumulation, and melting and evaporation in the zone of ablation.
96
equilibrium line
between accumulation and ablation zones. no gain or loss
97
Paternoster lakes
one of a series of glacial lakes connected by a single stream
98
horn
results when glaciers erode three or more arêtes, usually forming a sharp-edged peak
99
aretes
a thin, crest of rock left after two adjacent glaciers have worn a steep ridge into the rock
100
Fjord
A long, narrow, deep lake from the sea between steep slopes of a mountainous coast
101
U shaped valley
literally a U shaped Valley. formed when glaciers travel across and down a slope
102
Col
the lowest point on a mountain ridge between two peaks
103
tarn
a small mountain lake
104
hanging valley
a valley, the lower end of which opens high above a shore, usually caused by the rapid erosion of a cliff.
105
Glacial drift
the deposits (sediments, rocks, boulders, etc.) that moved by the glacier
106
Glacial Till
Upon melting, the drift material is deposited
107
Patterned Ground
also has been found on Mars which
is good evidence that groundwater once was near
the surface.
- water fills cracks in ground
108
Wisconsinan Glaciation
- last ice age
- triggered by motions of continents
- provided a snow-covered Antarctic continent and an ice-covered Arctic Ocean, restricted ocean flow paths, and changed atmospheric circulation
109
The Milankovitch Theory
As the Earth travels through space around the sun cyclical
variations in three elements of Earth-sun geometry combine
to produce variations in the amount of solar energy that
reaches Earth
110
Orbital Eccentricity
the shape of the Earth’s orbit around the Sun
| varies from nearly circular to slightly elliptical with a period of about 108,000 years.
111
Precession
Earth’s axis of rotation slowly revolves, tracing a circle over a period of about 26,000 years.
112
Obliquity
As the axis of rotation moves along the circle, it also varies its angle slightly from 22.1° to 24.5° with a period of about 41,000 years.
113
Periglacial
denotes an area adjacent to a glacier or ice sheet or otherwise subject to repeated freezing and thawing
114
felsenmeer
a surface covered with rocks
115
firn
Surface snow melts and refreezes on warm days and cold nights, compacting the snow and turning it into granular ice
116
glacial grooves
- Kelley’s Island
- resistant limestone bedrock was ‘grooved’ and ‘smoothed’ by the passing glaciers.
- evidence of glaciers in N. America
117
Glacial Erratics
are rocks that differ from native rocks in the area in size and type. These were used as additional evidence for the past presence of glaciers in southern latitudes
118
glacial outwash
formed of glacial sediments deposited by meltwater
