Honors Earth Science Final: Chapter 6- Glaciers, Deserts, and Wind Flashcards

Terms Definitions
Glacier
A thick mass of ice originating on the land from the compaction and recrystallization of snow, and shows evidence of past or present snow
Valley (Alpine) Glaciers
Glaciers found in mountain areas, where they usually follow valleys that were originally occupied streams
Ice Sheets
Flow in all directions from one or more centers and completely obscure all but the highest areas of underlying terrain, exist on a large scale, covering most of Greenland and Antartica
Zone of Fracture
Near the surface of a glacier, ice is brittle, upper 50 meters of glacier that is not prone to plastic flow (not enough pressure on it)
Flow, Plastic Material
Below about 50 meters, pressure is great causing the ice to _________ like _______________
Slipping
An important mechanism of glacial movement that consists of a whole ice mass __________ along the ground
Zone of Accumulation
Snow accumulation and ice formation occur here
Zone of Wastage
Beyond the zone of accumulation, where there is a net loss to the glacier, it happens because the snow from the previous winter melts and so does some of the glacier
Plucking
Glaciers erode land by lifting pieces of bedrock out of place
Abrasion
Ice and it's load of rock fragments slide over bedrock and act like sand paper creating pulverized rock
Till
Unsorted sediment deposited directly by ice
Stratified Drift
Relatively well-sorted sediment laid down by glacial meltwater
Moraines
The most widespread features created by glacial deposition, layers or ridges of till
Lateral Moraines
Associated with valley glaciers, formed along the sides of the valley
Medial Moraines
Form between two valley glaciers that have joined
End Moraines
Mark the former position of the font of the glacier
Ground Moraines
Undulating layer of till deposited as the ice front retreats, are common to both valley glaciers and ice sheets
Multiple Layers of Drift
Most convincing evidence for the occurrence of several glacial advances during the Ice Age
Ephermeral
All desert streams are dry most of the time
Running Water
What is responsible for most of the erosion in a desert?
Deflation
The lifting and removal of loose material, often produces shallow depressions and can also lower the surface by removing sand and silt
Blowouts
The shallow depressions cause by deflation
Desert Pavement
When sand and silt are removed during deflation, lowering the surface and leaving a smooth surface
Loess
Extensive blankets of silt, carried by wind in suspension
Dunes
Mounds and ridges of sand, formed from sediment that is carried as part of wind's bed load
Barchan Dunes
Solitary dunes shaped like crescent with their tips pointing down wind
Transverse Dunes
Series of long ridges oriented at right angles to prevailing winds
Longitudinal Dunes
Long ridges that are more or less parallel to the prevailing wind
Parabolic Dunes
Similar in shape to barchans except their tips point into the wind
Star Dunes
Isolated hills of sand that exhibit a complex form
Piedmont Glacier
Occupy broad lowlands at the bases of steep mountains and form when one or more valley glaciers emerge from the confining walls of the mountain valleys
Wind, Glaciers, Running Water
Three ways to erode
Climate
What has a strong influence on the nature and intensity of the earths external processes?
10 Percent
What percent of the earth is covered in glaciers?
Hydrologic Cycle and Rock Cycle
Glaciers are part of what 2 fundamental cycles in the earth system?
Ice Caps
Covers the uplands and plateaus, completely bury land, smaller than ice sheets
Flow
The movement of glacial ice
Plastic Flow
Movement within ice, ice is brittle solid until the pressure exerted upon it = weight of about 50 meters
Crevasses
When glacier moves over irregular terrain the zone of the fraction becomes under tension and cracks appear; can be up to 50 meters deep
Center
Flow is the greatest in the ____________ of glacier because of drag created by walls and floor of valley
Snow
The material from which glacial ice originates
Rhone Glacier
The glacier that was studied to figure out that the ice along the sides of the glacier move the slowest
Calving
Another way a glacier wastes, this is when a large piece of ice breaks off, creates icebergs
80 Percent
How much of an iceberg is submerged in water?
Glacial Budget
The balance or lack of balance between the accumulation of snow/ice at the upper end and the loss at the lower end
Ablation
Loss of ice/snow from a glacier
Glaciers
What are the best transporters of sediment?
Rock Flour
Sliding of rock fragments and ice over bedrock causing pulverized rock called ____________
Glacial Striations
When ice at the bottom of a glacier contains large rock fragments, long scratches called ____________ occur, can be used to measure the direction of movement of a glacier
V Shaped
Alpine valleys are originally this shape (because streams were above base level)
U Shaped, glacial trough
Alpine glaciers are changed, they widen, deepen and are in the shape of what _________, called a ___________
Hanging Valleys
The valleys of tributary glaciers are left hanging above the deeper cute valley from trunk glacier
Cirque
A bowl shaped depression at the head of a glacial valley, they have steep walls on three sides, but are open on one side to a valley, begin on parts of a mountainside that were enlarged due to frost wedging and plucking
Aretes
Sharp edged ridges seperating two adjacent glacial valleys
Horns
Sharp pyramid like peaks
Fjords
Deep, steep sided inlets of the sea, where mountains are adjacent to the ocean, they are glacial troughs that became submerged as the ice left and the valley and sea level rose following the ice age
Glacial Erratics
Boulders found in the till or lying free on the surface, they are used to trace the path of a lobe of ice
Outwash Plains
Meltwater from glacier moving in rapidly moving streams, this creates a flat, sloping plain consisting of materials deposited by meltwater streams in front of the ice sheet margin
Valley Trains
When an outwash plain is confined to a mountain valley
Kettles
Blocks of ice become buried in drift, when they melt there is a basin or depression in the ground
Drumlin
Streamlines asymmetrical hills composed of till, steep side faces direction of where ice advanced
Esker
Ridges composed of sand and gravel, they are deposits mad by streams flowing in tunnels beneath ice, near end of glacier
Kames
Steep sided hills composed of sand and gravel, they are made when glacial melt water washes sediment into openings and depressions in the end of glacier
Erosional Gaps
What makes it hard to reconstruct what happened during the ice age?
Sediment on the Ocean Floor
What provides an uninterupted record of climate cycle?
Pleistocene Epoch
Geologic time scale when major glacial episodes occurred
Pluvial Lakes
A lake formed during a period of increased rainfall, happened in nonglacial regions during when ice was advancing elsewhere during the pleistocene period
Plate Tectonics, Earth's Orbit, Reflectivity of Earth's Surface and Ocean Circulation
Causes of Glaciation
30 Percent
How much of the earth's surface is desert?
Desertification
The alteration of land to desert like conditions due to human activities
Chemical Weathering
Humid regions have what kind of weathering?
Mechanical Weathering
Dry regions have what kind of weathering?
Wash and Arroyo
Dry streams in America
Wadi
Dry stream in Arabia and North Africa
Donga
Dry stream in South America
Flash Floods
Occur when it does rain and due to lack of vegetation, there is high erosion
Streams
Lack tributaries and dry out before reaching sea, the few rivers that do not dry out but originate outside the desert
Interior Drainage
A discontinuous pattern of intermittent streams that do not flow out of the desert to the ocean
Alluvial Fan
A cone of debris resulting from a large amount of water rushing down mountain canyons, once it hits a valley, velocity slows and debris settle in fan shape
Playa Lake
When there is a ton of rain, streams may flow across alluvial fans enlarge and connect with other alluvial fans
Inselbergs
Due to erosion, mountain areas are reduced to a few large bedrock knobs projecting above the basin filled with sediment
Bajada
An apron of sediment along a mountain front, its when alluvial fans enlarge and connect with other alluvial fans
Increases
Velocity of wind _____________ with height above surface
Siltation
When larger grains of sand are rolled or skipped along = bedload
Louis Agassiz
The father of glaciology (the study of glaciers)
5,600 feet, 791
15,000 years ago, Boston was beneath __________ feet of ice, which is __________ John Hancock buildings stacked on top of each other
4
In the last 450,000 years, North America has undergone _______ ice ages
Laurentide, Greenland, Cordilleran
During the last ice age, the 3 ice sheets that covered North America were
Snowline
The elevation above which snow remains year round
Firn or Neve
Snow that has survived one summer and has begun the process of transformation into ice (usually about 25 years)
Tidewater Glacier
A valley glacier that ends in a lake or ocean
Retreating
A glacier that is melting fast than it is moving forward
165 Feet
Crevasses can be as deep as ________
Bergshrund
A crevasses that separates flowing ice from the head of a glacier
Serac
Is a tower of unstable ice that forms between crevasses, commonly in icefalls or other regions of accelerated glacier flow
Striation
Indicate the direction the glacier is moving
Grooves
Deep striations
Gouges
Half-moon shaped fractures on glaciated rock surfaces caused by the irregular jerky motion of a glacier
Truncated Spur
A steep bluff on the side of a glacial trough
Col
An arete that takes on a saddle shape
Horn
A pyramid shaped peak created by the presence of three or more cirques
Horn
What is Madderhorn in Switzerland an example of?
U Shaped
The general shape of a glacial valley
Glacial Trough
A glacial valley is also known as a _____________
Triangular Facet
A valley created by a tributary glacier that enters the main valley a great distance above the floor
Nunatak
A mountain peak that sticks out above a glacier
De Geer
The material is deposited in water = interesting formations
Orgives
Bands of light and dark layers of snow on a glacier
Ablation Hollow
Irregular features created in the surface of a glacier due to differences in wind and temperature on the glacier surface
Cyroconite
A depression in the surface of a glacier due to the heating of rocks
Glacier Table
A boulder perched on a pedestal of ice, the boulder protects the ice from ablation during sunny weather
Sun Cups
Is an ablation hollow that develops during intense sunshine
Penitents
Spires of ice found in the tropics due to differences in sublimation
Moulins
Nearly vertical channel in the ice that is formed by flowing water
Glacial Milk
When pulverized rock is mixed with water
Rouche Mountonee
Sheep back
Drumlin
A ramp deposit of sediment with one shallow and one steep side
Crag and Tail
Glacially eroded rocky hill with a tail of till formed down-glacier
Kame Terrace
A deposit, often sloping down valley more steeply than the valley floor, formed where a glacial stream ran along the glacier margin
Kame Delta
A deposit formed where a glacial stream entered into a pro-glacial lake
Varves
Bands of light and dark sediments
Jökulhlaup
Giant glacial flood, often caused by volcanism
Braided
Outwash plains have _________ stream patterns
Pater Noster Lakes
The latin word for "our father", rosary beds
Dry Falls
Water flowing over point a (a cataract) eroded the rocks at the base of the cliff.
Walden Pond
An example of a kettle
Crevasses
What form in the zone of fracture?
Snowline
What separates the zone of accumulation and the zone of wastage?
Crevasses
What happens when glaciers move along irregular terrain?
Aretes
Sharp edged ridges
Horns
Sharp pyramid like peaks
Horns and Aretes
What are the two things that could be formed by enlargement of cirques produced by plucking and frost action?
Isolated Horn
What is formed as cirques enlarge and cover
Lateral and Medial Moraines
What two types of moraines are associated with mountain valleys?
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