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• glaciology is the study of glacial activity
• Basic concepts
• Definition of glacier
• any moving mass of ice on Earth
• Classification of glaciers
• mountain(alpine) glaciers formed in and
  restricted to the mountainous areas on Earth and
  comprise a small amount of total glacial ice on
  Earth
• continental glaciersmassive ice on continents
  comprising about 95 of total global ice

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Changing of snow to ice
snow fall and accumulates and contains air
between flakes
as more snow accumulates, snowflakes farther down
are compressed forcing out a lot of the air
with increasing depth and pressure, snow
crystallizes to form ice, which can be considered
a rock
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• Theories and concepts of all glacial ice growth
  and demise
• changes in temperature and/or precipitation over
  a long time are the two most important conditions
  governing the growth and demise of glacial ice
• continental glaciers
• activity on sun solar flares and sun spots
• some believe a long term change in solar
  intensity can cause a global temperature change
  increasing or decreasing glaciers

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• greenhouse effect
• Long term increases or decreases of carbon
  dioxide in our atmosphere can increase or
  decrease global temperatures to affect amounts of
  global ice
• increases of CO2 1) burning of fossil fuels 2)
  volcanic activity--emissions of CO2
• decreases of CO2 1) chemical weathering of
  extruded igneous rocks
• plant use of CO2 for photosynthesis

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• Donn-Ewing concept (not well accepted)
• land bridge across Bering Straits controls amount
  of precipitation in the region by allowing
  different temperature bodies of water (Arctic and
  North Pacific Ocean) to mix when land bridge is
  submerged ( increased precipitation)and not mix
  when land bridge is exposed(decreased
  precipitation)
• this idea may explain the North American Ice
  Age-- glacial ice in Greenland is a remnant of
  that age

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Extent of global ice during North American Ice
Age
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• atmospheric particulates
• volcanic activity on a large scale can cause
  large amounts of particulates in the atmosphere
  resulting in reflection of sun energy and cooler
  global temperatures
• plate tectonics and position of continents at
  polar region and variation of Earths orbit
• these 2, appear to be more popular

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Position of plates before Continental Drift
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Changes of Earths Orbital Variations
1. Tilt of Earths Axis of Rotation (takes about
40,000 years to cycle from minimum to maximum)
maximum tilt angle can lead to a decrease of
glacial activity because warmer summer
temperatures melt more south polar ice
minimum tilt angle can lead to an increase of
glacial activity because south polar area
receives less sunlight
present day tilt, adjusting back from last ice age
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2. Shape of Earths Orbit (Eccentricitytakes
about 100,000 for cycle)
Eccentricity can cause a major climate change
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3. Wobble of Rotation Axis (Precession)
Precession can cause global changes
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http//highered.mcgraw-hill.com/sites/0073369365/s
tudent_view0/chapter16/milankovitch_cycles.html
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each individual variation cannot explain glacial
activity, but by combining them as Milankovitch
did, appeared to show better resultsbut still
debated by some
MILANKOVITCH CYCLES
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What about theories of growth and demise of
alpine glaciers ? growth and demise of alpine
glacial ice is more dependent on small term
changes as in seasonal temperature and
precipitation differences as is present in many
global mountainous regions. There can be alpine
glaciers active and caused by continental
glaciations
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• Alpine and Continental Glacial Regiment
  (movement)
• growth and demise of glacial ice is based on rate
  of accumulation versus the rate of
  wastage(melting) for alpine and continental
  glaciers

example of important alpine glacial areas
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Photo of snowline and areas of accumulation and
wastage for an alpine glacier
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• Alpine and Continental glacial flow at and below
  ice surface--brittle zonecrevasses at surface

brittle-crevasse zone slower flow
mobile ice fastest flow
A lot of friction with rocksslowest flow
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• Glacial deposits and erosion features
• all glacial deposits (Alpine and Continental) are
  called drift
• till is non-stratified drift and comprised of
  non sorted or a mixture of different particle
  sizes (see Wentworths scale)--deposited directly
  by the glacial ice
• outwash is stratified or layered drift with each
  layer being well sorted--deposited directly by
  glacial melt water

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Photo of till
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Example of Non-Layered Till and Layered
Outwash
Sorted Outwash
Non-sorted Till
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• Alpine glacial deposits and erosion features
• deposits--mostly till called moraine
• lateral moraine
• formed on sides of and present on surface of
  glacial ice and results from the plucking and
  pulverization of rock by the ice
• medial moraine
• formed by convergence of 2 lateral moraines from
  2 ice lobes

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• end (terminal) moraine
• a ridge of deposit contouring the shape of front
  of glacier formed from the discharged of
  materials moved within the glacier like a
  conveyor belt
• represents the maximum advance position of the
  glacier

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lateral moraine formed on sides of glacier
medial moraine formed from 2 lateral moraines
from intersecting glaciers
terminal morainemost forward movement of glacier
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• recessional moraine
• a deposit shaped similar to the end moraine
  formed during a subsequent advancement of glacier
  during its overall demise
• many recessional moraines may occur during the
  demise of a glacier
• erosion features
• formed from the plucking nature of the glacier

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• cirque
• semi-circular or amphitheater shaped--a tarn or
  cirque lake can be present ---paternoster lakes
  are a chain of interconnected tarns

2 cirques and tarns
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• horn
• a peaked or pointed feature resulting from the
  formation of a series of closely associated
  cirques
• best example is the Matterhorn

Matterhorn in the Alps
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• arete
• a jagged or sawtooth ridge left between 2 glacial
  lobes gouging rock material as they move to a
  lower elevation

cirques and aretes
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• U shaped valley
• is the typical shape of a valley carved by a
  glacier
• is best observed in the front profile view as you
  look up the valley

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• hanging valley
• formed from a glacial tributary lobe and hangs
  over the main glacial valley
• best example of this is Bridalveil Falls in
  Yosemite National Park

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Review of some alpine glacial depositional
and erosion features
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• Continental glaciers
• glacial ice in Antarctic and Greenland comprise
  more than 90 of all glacial ice on Earth
• if all the ice melted sea level would rise about
  215 feet(195 feet from all ice associated with
  Antarctic and 20 feet for that from Greenland)

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Glacial ice deposits on Antarctic and Greenland
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Effects of continental glacial ice
formation or melting on sea level
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• erosional features
• there are a few types of erosion features
  associated with continental glaciers like the
  Great Lakes and Driftless area in Wisconsin, but
  the depositional features are more abundant
• depositional features
• till
• ground moraine--an undulating massive blanket
  like deposit formed on ground where glacial ice
  was present

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• end moraine--see alpine notes
• recessional moraine--see alpine notes
• drumlin--a streamlined symmetric inverted spoon
  head shaped hill whose steep side faces the
  direction from which the glacier
  advanced---Bunker Hill in Boston is a drumlin and
  is where a famous Revolutionary War battle was
  fought

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Field of drumlins in Baraboo, Wisconsin
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Drumlinssteep side facing direction of
glaciers retreat
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• Outwash (well sorted)
• outwash plain--a relatively flat massive blanket
  like deposit consisting of layered and well
  sorted particles deposited by glacial melt water
  in the front and sides of the glacial ice
• esker--a winding ridge comprised primarily of
  sand and gravel layers deposited by a stream
  flowing in a tunnel beneath a glacier near its
  terminus

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Esker
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• kame--a steep sided hill comprised of sand and
  gravel layers originating from the collection of
  sediment in openings in stagnant ice
• kettle
• hole or lake formed from a large melted block of
  ice buried in the ground moraine or outwash plain

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Review of some continental glacial
depositional features
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drumlins
recessional moraines
esker
kettle lakes
terminal moraine