Hydromorphology and Glaciation Flashcards
1
Q
What is an Aeolian process?
A
Eolian processes include erosion, transportation, and deposition accomplished by wind.
2
Q
The ability of wind to move materials is less than that of water or ice. Why?
A
Because air is much less dense than water or ice.
3
Q
True or False: Like all agents of erosion, wind erodes, transports and deposits.
A
True
4
Q
Is wind an affective agent of erosion?
A
Wind is, like water, a fluid, but being less dense, is a less effective agent of erosion.
5
Q
Which is more effective at erosion, wind or water? Why?
A
Water, because it is dense.
6
Q
Among large-, intermediate-, and small-sized grains, which one moves most easily by wind?
A
Intermediate particles are easy to move, because they can bounce along.
7
Q
Why are small particles difficult to erode?
A
Small particles are difficult to move because they have a mutual cohesiveness and they present a smooth surface to the wind.
8
Q
What are the three movements of particles by wind?
A
Saltation
Suspension
Creep
9
Q
Define Saltation:
A
bouncing, skipping, some impact when they land can act as erosive work
10
Q
Define Suspension:
A
smallest of particles remain in suspension
11
Q
Define Creep:
A
near the surface, traction and sliding along the ground
12
Q
About ______ of wind transport occurs via saltation, which is very important to eolian transport.
A
80%
13
Q
How is saltation accomplished?
A
Aerodynamic lift
14
Q
what are some important factors of Saltation?
A
Bouncing and IMPACT
Inertia
15
Q
What are the two principal wind-erosion processes?
A
Deflation
Abraison
16
Q
Define Deflation:
A
Removing and lifting individual loose particles from the ground surface. Deflating the landscape.
17
Q
Define Abrasion:
A
grinding rock surface by the “sandblasting” action of particles captured in the air.
18
Q
What does the rate of abrasion depend on?
A
hardness of surface rocks
wind speed
wind constancy
19
Q
What are Ventifacts?
A
Artifacts of the Wind
20
Q
What are characteristics of ventifacts?
A
Pitted, fluted, or polished from eolian erosion
21
Q
What are Yardangs?
A
Yardangs refer to large scale streamlining rock structures (formed by deflation and abrasion) that are aligned parallel to the most effective (or dominant) wind direction.
22
Q
How high to Yardangs get?
A
Kilometres in length and many meters in height
23
Q
What are Gobi?
A
Desert Pavemnts in China
24
Q
What are the two theories of Gobi?
A
Deflation vs. Moisture
25
True or False: Only 10% of desert areas are covered with sand.
True
26
What area do desert pavements predominate across?
Subtropical Landscapes
27
Define Dunes:
Sand grains generally are deposited as transient ridges or hills
28
What is an extensive area of dunes called in North Africa?
Erg or Sand Sea
29
Provide a Dune profile:
Wind erosion and deposition work together to build a dunes characteristic profile. A dune grows as wind-borne particles accumulate on the gentler, windward slope, then cascade down the steep slip face of the leeward slope
30
What is the angle of repose in reference to a dune?
The off balance forces holding materials in place, is usually 30-34°
31
True or False: The dune, over time, migrates, this is where deposition comes into play.
True
32
What are the three types of dune formation?
Crescentic
Linear
Star
33
________________:
-Solitary, crescent shaped dune
-Horns point downwind
-Sand Supply limited
-Strong wind
Barchan Dune
34
_________________:
-crescentic dune
-Open horns face upwind (opposite to barchan shape)
-Vegetation anchors certain sections (arms) of the dune in place, while others migrate.
Parabolic Dune
35
__________________:
-Crescentic dune
-Large Fields of dunes, resemble ripples on a large scale
-Occurs in areas with abundant supply of sand and constant wind direction
Transverse Dune
36
True or False: Barchan dunes grow together into a transverse formation if sand supply increases overtime.
True
37
What are the three types of Crescentic Dunes?
Barchan
Parabolic
Transverse
38
____________________: -
Linear dunes, long straight ridges, approximately parallel with the prevailing wind direction.
-Moderate to low sand supply, strong prevailing winds which change direction slightly and converge.
Longitudinal Dunes
39
________________:
-The largest dune formations (can approach 200m in height)
-Result from shifting wind direction and abundant sand supply, opposite of longitudinal dunes.
Star Dunes
40
What do Dome Dunes form domes?
Vegetation might result in a collection of sand, resulting in a dome shape dune.
41
What are the three environmental conditions which influence Dune formation?
Wind
Vegetation
Sand
42
_____________ Dunes often have more sand.
Transverse
43
________________ dunes result from more wind.
Longitudinal
44
There are ____________ dunes where vegetation is found.
no
45
True or False: About 77% of Earth’s freshwater is frozen.
True
46
Define a Glacier:
a large mass of ice resting on land or floating as an ice shelf in the sea adjacent to land.
47
How do glaciers move?
slowly, in stream like patterns
48
What are glacial and interglacial periods?
Periods of time when the earth is warming vs. cooling, usually around 20,000 year differences
49
What is Glacial Lake Agassiz?
The largest of the ice marginal lakes, Glacial Lake Agassiz stretched from Saskatchewan to Ontario into south Dakota and Minnesota.
-Stratigraphic evidence of glacial lake Agassiz is found over an area of approximately 950,000 km2, though the lake never covered this entire area at any one time.
50
What is a Glacial Spillway? Example?
valleys that are much wider than the river that currently occupies them
-ex. Qu’Appelle Valley in Saskatchewan
51
How many steps are there to glacial formation?
3
52
What is the first step of glacial formation?
Snow survives the summer. Note: glaciers occur in areas with permanent snow cover
53
What is the 2nd step of glacial formation?
-In the following winter, the old snow is slowly pressured and re-crystallized into firn.
54
What is Firn?
Firn is at an intermediate stage between snow and glacial ice. It has a compact and granular texture.
55
What is the third step of glacial formation?
After many years pass, dense glacial ice is formed in an analogous process to the metamorphic process: snow and firn (sediments) are pressured and re-crystallized into a dense glacial ice (metamorphic rock).
56
What are the two types of Glaciers?
Apline
Continental
57
Define an Alpine Glacier:
a glacier in a mountain range is an alpine glacier or mountain glacier.
58
Where are Alpine Glaciers mostly found?
Alpine comes from the Alps of central Europe, where many mountain glaciers are found.
59
What are the four common subtypes of Alpine Glaciers?
Cirque
Valley
Piedmont
Tidewater
60
___________ glacier: glacier in a bowl-shaped recess at the head of a valley
Cirque
61
_______________ glacier: in steep-walled valleys
Valley
62
_____________ glacier: at the base of a mountain range
Piedmont
63
_____________ glacier: a glacier ends in a body of water influenced by tides.
Tidewater
64
Define a Continental Glacier:
A continuous mass of ice with a much larger scale than individual alpine glaciers are a continental glacier.
65
What is an ice sheet?
An ice sheet is a mass of glacier ice that covers an area of more than 50,000 km2.
66
What are the two major ice sheets?
Antarctic
Greenland
67
What are the two subtypes of Continuous ice over mountain locations?
Ice Caps
Ice Fields
68
What is an ice cap?
An ice cap is roughly circular and covers an area of less than 50,000 km2
69
What is an ice field?
An ice field is in an elongated pattern (ice field’s area usually is less than that of an ice cap).
70
Give an example of an ice field:
The Patagonian ice field in the Andean mountains is the largest in the world 90kms wide, and 360kms long
71
What is Glacial Mass Balance?
A glacier in disequilibrium will either advance or retreat
-A glacier in equilibrium has equivalent rates of accumulation (snow) and ablation (melt/loss).
72
What will a glacier with positive net mass balance do?
Advance (more accumulation than ablation)
73
What will a glacier with negative net mass balance do?
Retreat (more ablation than accumulation)
74
True or False: Regardless of whether the glacier is advancing or retreating, it flows downslope under its own weight.
True
75
What is glacial movement driven by?
Deformation
Basal Slip
76
______________ presence in the basal layer can lubricate the glacial movement.
Water
77
How does Dendrochronology help estimate glacial advance/retreat?
By dating dead trees that were killed (run over) during advance… and by ageing living trees growing on depositional landforms left behind by glaciers.
78
What are some agents of erosion from glaciers?
running water
ocean currents
moving air
79
Define Glacier erosion:
-The process by which a glacier erodes the landscape is like a large excavation project, with the glacier hauling debris from one site to another for deposition.
-The passing glacier mechanically picks up rock material and carries it away in a process known as glacial plucking.
-Debris is carried on its surface and is also transported internally, or englacially, embedded within the glacier itself.
80
What does Englacially mean?
Embedded within the glacier
81
What happens to the the frozen basal layers of a glacier during erosion? What is that process called?
the glacier enable the ice mass to scour the landscape like sandpaper as it moves.
-Abrasion
82
What does Abrasion do in glacier erosion?
produces a smooth surface on exposed rock, which shines with glacial polish when the glacier retreats.
83
A landscape feature produced by both glacial plucking and abrasion is a _______________.
Roche moutonnée
84
What is a Roche moutonnée?
This landform has a characteristic gently sloping upstream side (stoss side) that is polished smoothly by glacial action and an abrupt and steep downstream side (lee side) where the glacier plucked rock pieces.
85
Explain the process of Glacial Plucking:
Caused by water freezing and thawing in joints, causing cracking and separation. It is also caused by water freezing around a rock and entraining it in the flow of ice.
86
What is an example of glacial plucking?
Finger Lakes, NY
87
What are Glacial Valleys?
if this landscape becomes cold enough, to support the growth of glaciers, ice can fill in preexisting V-shaped valleys.
88
What happens to Glacial Valleys overtime?
Then over time it becomes a u-shaped valley. It can shape many different landscape features.
89
What do Glacial Drifts refer to?
Glacial drift refers to all glacial deposits, both unsorted and sorted.
90
What is a sorted glacial drift AKA?
Stratified Drift
91
_____________: the direct ice deposits left as unstratified and unsorted debris.
Till
92
What happens as a glacier flows to a lower elevation?
a wide range of rock fragments becomes entrained on its surface or embedded within its mass or in its base
93
What do retreating glaciers do?
They can leave behind large rocks
94
Explain Glacial Till:
glaciers carrying larger particles, sediments, boulders and grinding those things along the base, as its sliding down a glacial valley, we see evidence of resistant rock being quite heavy.
95
What are Moraines?
The deposition of glacial sediments
96
________________: forms along each side of a glacier.
Lateral Moraine
97
_________________: If two glaciers with lateral moraines join
Medial Moraine
98
___________________: A depositional till that is generally spread across a surface
Ground Moraine/Till Plain
99
What are Ground Moraines/Till Plain good at?
Covering up former landscape features.
100
_________________: Eroded debris that is dropped at the glacier’s farthest extent.
Terminal moraine
101
What is a Kettle Lake?
An isolated block of ice remains in a ground moraine or an outwash plain after a glacier retreated.
102
What happens when ice begins to melt in a Kettle Lake?
material continues to accumulate around the melting ice block. When the block finally melts, it leaves behind a steep sided hole.
103
How did Kettle Lakes get their name?
During this period, material continues to accumulate around the melting ice block. When the block finally melts, it leaves behind a steep sided hole.
-Such a feature then frequently fills with water, called a kettle.
104
What is topography of Knot and Kettles?
retreat of large continental glaciers, barriers by water, melt and leave the depression in the landscape.
105
What is an Esker?
Esker is a sinuously curving, narrow ridge of coarse sand and gravel.
106
Where do Eskers form?
It forms along the channel of a meltwater stream that flows beneath a glacier, in an ice tunnel, or between ice walls.
107
Esker; As a glacier retreats, the steep-sided esker is left behind in a pattern __________ to the path of glacier.
parallel
