Glaciation Flashcards
Theory of ice ages
Developed in 1837 by louis Agassiz
evidence for glaciation in regions with no glaciers
The present is the key to the past
What is a glacier
large, long lasting river of ice that forms on land, undergoes internal deformation, and creates glacial landforms
What are glaciers made of
compressed and recrystallized snow
Order these from most to least compacted: Neve, glacier ice, firn, and snowfall
glacier ice, firn, neve, snowfall
Do glaciers often carry large sediment loads
yes
Where do glaciers form
at high elevation, at high latitudes (near the poles of the earth),
Glaciers have a large range in what 2 characteristics
size and age
What are 5 terms to describe the zones of a glacier
Zone of accumulation, equilibrium line, crevasses, zone of wastage/ablation, terminus
Landforms: glaciers form on land, undergo internal __________, and create glacial landforms
deformation
Brittle vs ductile deformation: glaciers deform through _______ deformation at their surface and _______ deformation at depth
brittle
plastic
For bedrock erosion is their water under the glacier
yes
Is there water under the glacier for plucking and abrasion
no
What are the three different ways ice moves
basal sliding, internal flow, and faulting
When ice movement occurs, what is picked up from the base of the ice and transported up towards the surface
sediment
ice flows from _____ to ______ surfaces
high to low surfaces
ice flows from the zone of ________ to the zone of _________
accumulation
ablation
Define mass balance
relative rate of accumulation and wastage. how much is being melted at the zone of ablation and how much is accumulating at the zone of accumulation
Where would we find an alpine glacier
mountainous areas
What are continental glaciers
they cover large areas and are not confined to high elevations
What are two types of continental glaciers
Antarctic and greenland
What are the two principle types of glaciers
alpine glaciers and continental glaciers
Why is a glacier striation formed
when the glacier moves across a rock it scratches it
describe a cirque glaciers
accumulates in a bowl like shape in the mountains
describe a valley glacier
found in valleys, extending out from mountains
describe a piedmont glacier
form where valley glaciers spread out onto a flatter area in a larger valley or on a plain
describe temperate glaciers
glaciers hat are near their melting point and have meltwater coming off them year round
describe a polar glacier
ice in the glacier is frozen year round and ice loss is primarily from sublimation
what is sublimation
transformation of ice to gaseous water - without melting in between
describe subpolar glaciers
They are between polar and temperature climate conditions and experience seasonal melting and water runoff
describe an ice shelf
the ice from the glacier extends over a water body, water is able to flow underneath
describe an outlet glacier
extends outward from continental glaciers or icecaps
Does erosion from a glacier cause a V-shaped valley or u-shaped valley
u-shaped valley
escribe a horn
erosion occurs when cirques surround the mountain and erode it
describe a cirque and aretes
erosion feature that form a rocky ledge between the cirques
describe a hanging valley
erosion feature that forms a little ledge and u-shaped valley between mountains
describe a paster noster lake
little streams and lakes that fill erosional features
describe glacial till
unstratified and unsorted sediment deposited by glaciers
What are the 3 types of moraines
medial(travels along the middle of the glacier), terminal, and lateral
What do we call sorted sediments deposited by a river flowing under or through a glacier
esker
what do we call depressions left by melted ice blocks
kettle lakes
What are features of depositions
esker, kettle lakes, drumlins, moraine, glacial till, kame, erratics (boulders)
describe an outwash plain
it is found at the terminus end of glaciers. water transports sediments deposited by the glacier.
Why are outwash plains different than glacial till
you can find sorted sediments in outwash plains.
describe roches moutonnees
hill features formed at the base of glaciers. glacial plucking on the downstream side creates jagged cliff. the upstream side often has striations, smoothed
Describe isostacy
The crust floats on the mantle and the level it floats at depends on the weight of the crust
how long ago was the last ice age
20,000 years ago
What is isostatic rebound
as mass is removed through an ice sheet melting or erosion, continents float higher
Are glaciers currently getting bigger or smaller
they are shrinking
earths recent history has been characterized by cycles of ice ages and ______________ periods
interglacial
what are the glacial - interglacial cycle controlled by
amount of solar radiation reaching different parts of the earth
What are the three types of Milankovitch cycles
eccentricity, obliquity, and precession
describe eccentricity
shape of the earth changes - less circular or more circular
describe obliquity
angle of earths axis changes
describe precession
wobbling of the earth axis changes
Insolation cycle represents what?
the overall change of the earths cycle. addition of obliquity cycle, eccentricity cycle, and precession cycle. Describes energy reaching the earths surface
What other two important graphs fluctuate at the same pattern as the insolation cycle does
the oxygen isotope records and the warming and cooling cycle
What is the uplift weathering hypothesis
global rate of chemical weathering is dependent on availability of fresh rock
what is orogenesis
mountain building
As new ________-rich crust is exposed to weathering, atmospheric ____ is consumed and the climate cools
silicate
CO2
What is eustacy
related to the volume of water in the ocean. It is a worldwide change of sea level
Cooler climate: more water stored as ice, sea levels ______
warmer climate: water melts from ice, and sea levels ______
drops
rises
What is thermohaline circulation
is id driven by temperature and salinity gradients and has big influence on global climate patterns
is cold water or warm water denser
cold water
is salt water or fresh water heavier
salt water
What does ocean circulation do
transports heat around the ocean on a global scale. Patterns include vertical convection and horizontal movement
formation of ice sheets in polar regions causes salinity _________ in polar ocean water
increase
What is the younger dryas
a moment of rapid climate change, glaciers can back big
What is the hypothesis of why the younger dryas occurred
large pulse of fresh water disrupted ocean currents and this cooled climate in the northern hemisphere for about 1000 years
what is the polar vortex
a stream and circulation of cold air. it can change or head outwards from the poles when there is different air pressure and winds
