STRATIGRAPHY AND SEDIMENTATION (GLACIER) Flashcards
1
Q
How much of Earth’s and surface is coverd by glacier?
A
10%
2
Q
Thick ice mass formed over hundreds or thousands of years
A
Glacier
3
Q
Processes in Glacier formation
A
Accumulation
Compaction
Recyrstallization
4
Q
Small glaciers which occupy lofty mountains bounded by precipitous rock walls and is a stream of ice that flows downvalley from a snow accumulation center near its head
A
Valley Glacier
5
Q
A longer than wide type of valley glacier
A
alpine Glacier
6
Q
An example of Valley Glacier in Alaska
A
Hubbard Glacier,
Yukon Territory
7
Q
Larger than valley glaciers, enrmous masses flow out in all directions from one or more snow accumulation centers and completely obscure all but the highest areas of the underlying terrain
A
Ice Sheet
8
Q
Ice sheet in the northern hemisphere
A
Greenland
9
Q
Ice sheet in the southern hemisphere
A
Antarctica
10
Q
The date in history that glacial ice covered large portions of N America, Europe and Siberia some 18000 years ago
A
Last Glacial Maximum
11
Q
Is Arctic Ocean covered by glacier?
A
No, it is coverd by Sea Ice which is much thinner than Glaciers
12
Q
Do glaciers form on water?
A
No they form on land
13
Q
Largest Island on Earth sitauted between 60-80 deg N Lat
A
Greenland
14
Q
How much of Greenland is covered by ice sheet?
A
80% or 1.7M sq.KM
15
Q
What is the thickness of Glacier in Greenlan
A
1500 m
16
Q
What is the max thickenss of Antarctic Ice Sheet
A
4300 m
17
Q
How much are is covered by Antarctic Ice Sheet
A
13.9 M sq.km. / 5460000 sq miles
18
Q
How much area is covered by Ice Shelves in Antarctic
A
1.4 M sq km / 546000 sq.miles
19
Q
What is the proper term for Greenland and Antarctic
A
Continental Ice Sheets
20
Q
Large, relatively flat masses of floating ice that extend seaward from the coast but remain attached to the land
A
Ice Shelves
21
Q
Largest Ice shelves on Earth
A
Ross and Ronne-Filcher
22
Q
Type of glacier covering uplans and plateaus which completely bury the underlying landscape but are smaller than conitental-scale feature
A
Ice caps
23
Q
Type of glaciers that occupy Broad lowlands at the bases of a steep mountain and form when one ot more valley glaciers emerge from the confining walls of mountain valleys
A
Piedmont Glacier
24
Q
Largest piedmont Glacier in Alaska
A
Malaspina Glacier
25
Toungues of ice which are valley glaciers which are avenues for ice movement from an ice cap or ice sheet through mountainous terrain to the sea extending outward from the margins of these larger ice masses
Outlet Glacier
26
Forms of Ice Movement
1) Plastic Flow
2) Basal Slip
27
At which depth does Ice begin to behave plastically
50 m or 165 feet
28
This happens when the entire mass of ice slips along the ground
Basal Slip
29
which portion of the glaciers move slower due to frictional drag?
Lower portion
30
The uppermost 50 meters portion of a glacier
Zone of Fracture
31
Gaping cracks in the uppermost part of glaciers caused by tension when glaciers move along irregular terrain
Crevasses
32
In which part of the glacier is flow the greatest?
at the center
33
Glacier in Switzerland in which movement of ice has been studied
Rhone Glacier
34
extreme rapid advance of glaciers
surges
35
What is the ranking of antarctica based on the size of continents?
5th
36
The Coldest, Windiest and Highest average elevation
Antarctica
37
Latitude of Antarctic Circle
66.5 S Lat
38
Type of climate in which the ave temp of the warmest month is 0 deg celsius or 32 F
Ice Cap Climate
39
Land formation which separates East from West Antarctica
Transantarctic Mountains
40
Highest peak in Antarctica
Vinsons Massif
41
The raw material from which glacial ice originates
Snow
42
The zone where snow accumulates and ice forms which thickens the glacier and promotes movement
Zone of Accumulation
43
Outer limits of zone accumulation which is sea level in polar regions and 5000m in places near the equator
Snowline
44
Zone where there is a net loss to the glacier as snow from the previous winter melts as well as some glacial ice
Zone of Wastage
45
The process of breaking large pieces of the glacier on its front part which creates Iceberg especially in places where glacier has reached the sea or lake
Calving
46
how much of icebergs' mass are submerged in water
more than 80%
47
The balance or lack of balance between the accumulation at the upper end of the glaicer and loss at the lower part of the glacier
Glacial Budget
48
When does a glacier is said to be receding?
When forward movement is so slow to offset the rate of wastage
49
What is plucking?
Meltwater goes into cracks and joints of the rock floor of glaciers and freezes. As it expands, it exerts tremendous presure and breaks the rock
50
What is Abrasion?
Processes of smoothening the bedrock when the ice loaded with rock fragments slide over it.
51
The pulverized rock produced by glacial gristmill
Rock Flour
52
Long scratches and grooves embedded into the bedrock due to abrasion which can denote glacial movement
Glacial Striations
53
When do glacier produce striations?
When the rock fragments carried by the ice are large
54
Factors that affect differential erosion by ice
1. Rate of Movement
2. Thickness of ice
3. Qualities of rock containe at the base of the ice
4. Erodability of the bedrock
55
U-shaped valleys formed as glacier widens and deepends them
Glacial Trough
56
Valleys left by tributary glaciers that are left standing above the trunk glacier or glacier trough
Hanging Valleys
57
Bowl-shaped valley which have precipitous walls on three sides but are open on the downvalley side and is the focal point of the glacier's growth because it is situated within the zone of accumulation
Cirque
58
A lake that usually occupies the cirque basin after the glacier melt away
Tarn
59
Sinuous sharp-edged ridges formed by glaciers
Aretes
60
Sharp, pyramidlike peaks formed by glaciers
Horns
61
Famous Horn in Switzerland
Matterhorn
62
Deep, often spectacular, steep side inlets of the sea that exists in many high-latitude areas of the world where mountains are adjacent to the ocean forme when the ice melts an the remnant glacial trough was submerged due to sea level rise
Fjords
63
An all embracing term for sediments of glacial origin no matter how, where, or ,in what form they were deposited
Glacial Drift
64
A type of glacial drift deposited directly by glacier deposited as ice melts and drops its load of rock debris; Poorly sorted
till
65
A type of glacial drift deposited by the glacial meltwater that are well sorted according to size and weight
Stratified Drift
66
Boulders found in the till or lying free on the surface that are unrelated to the bedrock
Glacial erratics
67
Simply layers or ridges of Till
Moraines
68
Ridges along the sides of the valley left from the large quantities of debris of valley walls formed by erosion of valley glacier
Lateral moraines
69
Formed when two valley glaciers coalesce to form a single ice stream thus the till that was formerly on the edges now form a single dark stripe of debri in te middle of the newly enlarged glacier
Medial moraine
70
a ridge of till that forms at the terminus of a glacier an is formed when a state of equilibrium is attained between wastage and ice accumulation - in a state of quilibrium
End Moraine
71
Forms when gently rolling layer of till is deposited as the ice front recedes and has leveling effect which usually fills low spots and clogging old stream channels
Ground Moraine
72
The very first end moraine to form which marks the farthers advance of the glacier
Terminal End Moraine
73
The end moraines that forms as the ice front occasionally stabilizes during retreat
Recessional End Moraine
74
A ramplike accumulation of stratified drift found adjacent to the downstream edge of most end moraines and is formed in ice sheets when metlwater loses velocity and drop much of its bedload
Outwash Plain
75
A ramplike accumulation of stratified drift found adjacent to the downstream edge of most end moraines and is confined in mountain valley when metlwater loses velocity and drop much of its bedload
Valley Train
76
A pockmarked basins or depressions on end moraines, outwash plains, and valley trains that is formed when a block of stagnant ice was buried in dirft and eventually melt leaving pits with glacial sediment. Usually does not exceed km in diameter
Kettles
77
Streamlined assymetrical hills compose of till with height range of 15-60m and length of 0.4-0.8 km formed in the zone of flow within an active glacier
Drumlins
78
clusters of drumlins
Drumlin Field
79
What directions is denoted by the steep side of the hill?
The direction from which the ice came from
80
What direction is denoted by the gentle side of the hill?
The diection to which the ice moved
81
Sinouos ridge of sand and gravel landforms found in places the were once occupied by glaciers an is formed by deposition of stream flowing in tunnels beneath the ice near the terminus of glacier - Stratified Drift
Eskers
82
Steep-sided hills form when meltwater washes away sediments into openings or depression of stagnatn wasting terminus of a glacier thus when ice melts, the stratified drift is left as mounds or hills
Kames
83
Other effects of glaciers?
1) Extinction of Ogranisms
2. Crust subsidence and rebound
3. Sea Level Change
4. Change of Drainage Patterns
84
A bay in canada currently experiencing crustal rebound
Hudson Bay
85
The largest proglacial lake to form during the Ice Age in North America
Lake Agassiz
86
Lakes that are relatively small and short lived which are formed as ice sheets and alpine glaciers act as dams trapping glacial meltwater and trapping the flow of rivers. Situated between the ice sheet and sloping land on the other side.
Proglacial Lakes
87
Whats the implication to sea level when ice sheets increase in size?
Sea Level falls and shoreline moves seawards
88
Lakes in semi arid and arid environment which were formed due to lower evaporation rates and moderate precipitation rates caused by the presence of glaciers
Pluvial Lakes
89
This is a pluvial lake formed in North America
Lake Bonneville
90
Remnant of Lake Bonneville un Utah
Great Salt Lake
91
This is a complex period characterized by a number of glacial ice advance and withdrawal
Ice Age
92
Rate of glacial or interglacial cycles
100,000 years
93
Age of Antarctic Ice Sheet
30 Million Years
94
Sedimentary rock formed when glacial till becomes lithified
Tillite
95
how many precambria glacial episodes are there?
2 (2Ga and 600Ma)
96
Causes of Ice Ages?
1) Plate Tectonics
97
How does plate tectonics contribute to ice age?
1) The position of the continents
2) Climate Change due to changing positions of continents
98
What explains the alternation between glacial and interglacial climates?
Milankovitch Hypothesis
99
Who formulated Milankovitch Cycles?
Milutin Milankovitch
100
Whats the main premise of Milankovitch Hypthesis?
Earth's climate is principally controlled by variation in incoming solar radiation
101
Variations in the shapes of Earths Orbit around the sun
Eccentricity
102
Change in the angle of Earth's Axis
Obliquity
103
Wobbling of Earth's Axis
Precession
104
Cycle of change in exccentricity
100,000 years
105
Cycle of change in obliquity
41,000 years
106
Current axis of rotation of earth
23.5 degrees
107
Maximum tilt?
24.5 degrees
108
Minimum Tilt?
22 degrees
109
Cycle of Earth's wobble
26,000 years
110
current star where the axis points at
North Star
111
The alternate star in terms of precession
Vega
112
What is the indication of the increase in CO2 and Methane in the atmosphere
Increase in termperature
113
Why is sunlight unable to warm the planet during ice age?
Because surface are mostly covered with ice and sunlight or energy is relected back to space
114
other factors that enable ice age?
1) Decrease in Greenhouse gases
2. Reflectivity of Earth's Surface
3. Ocean Circulation
