SedimentLandform Assemblages I

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Sediment-Landform Assemblages I

• SubglacialandIce-marginal

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Ice-marginal Environments
Till Ablation till
G-lac. Drift Dropstones
G-lac. Drift Kame delta
Till Lodgment
Till Moraines
Alluvium Kame terraces
Alluvium Outwash/drift
Alluvium Eskers
Alluvium Outwash
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Subglacial - Materials

• Ice
• Bed
• Rock
• Impermeable?
• Low/high shear strength?
• Till (as above)
• Glaciofluvial

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Landforms

• Typically streamlined
• Erosional or depositional?
• Glacial or glaciofluvial?
• Discrete or continuous distribution?

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Landforms
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Flutes and Drumlins
Images courtesy GSC http//sts.gsc.nrcan.gc.ca/cl
f/landscapes.asp
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Rogen (Washboard) Moraine

• Grounding line or
• Subglacial megafloods?

Image courtesy GSC http//sts.gsc.nrcan.gc.ca/clf
/landscapes.asp
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De Geer Moraine
Image courtesy GSC http//sts.gsc.nrcan.gc.ca/clf
/landscapes.asp
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Other annual(?) moraines

• Hepburns Mesa (Paradise Valley)

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Other Subglacial Features

• Voltaire, ND quad crevasse fill?

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Holocene Moraines
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Holocene Moraines
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Pleistocene Moraines
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Pleistocene Moraines
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Pleistocene Moraines
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Origin of Moraines

• Push
• Thrust
• Squeeze
• Dump

Erosion as particles
Erosion as mass
Extrusion as fluid
Depositionas particles or fluid
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Origin of Moraines

• Push
• Thrust
• Squeeze
• Dump

Erosion as particles
Erosion as mass
Extrusion as fluid
Depositionas particles or fluid
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Medial and Interlobate Moraines

• Thaddeus Josephson
• April 9, 2003
• Geol. 445

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Medial Moraines

• Supraglacial
• Englacial
• Subglacial
• Can be traced from glacial to proglacial
• Poor preservation on substrate

http//www.panopt.com/photogra/washburn/bw1355.jpe
g
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Morphology

• Irregular-hummocky
• Poor sorting
• Recognizable lithology
• Angular clasts
• Intense reworking

http//uregina.ca/sauchyn/geog323/351.jpg
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Medial moraine classification
www.uwsp.edu/geo/faculty/ritter/images/lithosphere
/glacial/medial_moraine_Baffin_GSC
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Ice Stream Interaction (ISI)

• Most common
• Confluent lateral moraines
• Immediate surface expression
• Below firn line

http//www.env.duke.edu/eos/geo41/gl1027.gif
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AblationDominant (AD)
( Rodgerson and Eyles 1979 )

• Differential ablation
• Crevasse injection
• Basal debris elevated into septa
• Often lee side of bedrock knob
• Rock fall transport
• Englacially above firn line
• Supraglacially below firn line

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Ablation Dominant (AD)( Rodgerson and Eyles 1979
)
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Avalanche Type( Rogerson, Olson, and Branson
1986 )

• Torngat (Labrador study)
• Fed from avalanche gullies
• Bedding during event
• Ingestion into bergshrund/crevasse

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Black Rapids Glacier
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Interlobate Moraines

• Much larger
• Confluent glacier lobes
• Few remnants
• Reworked by glaciofluvial events
• Eskers
• Cape Cod

http//sts.gsc.nrcan.gc.ca/page1/landf/atlantic/ne
wf/st_georg/interlob.jpg
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References

• Gomez, B. and R.J. Small , 1985. Medial Moraines
  of the Haut Glacier DArrolla, Valais,
  Switzerland Debris Supply and Implications for
  Moraine Formation. Journal of Glaciology. Vol.
  31, No. 109. Pages 303-307.
• Rodgerson, R.J., M.E. Olson, and D. Branson ,
  1986. Medial Moraines and Surface Melt on
  Glaciers of the Torngat Mountains, Northern
  Labrador, Canada. Journal of Glaciology. Vol.
  32, No. 112. Pages 350-354.
• Small, R.J., M.J. Clark, and T.J.P. Cawse , 1979.
  Medial Moraines on Alpine Glaciers. Journal of
  Glaciology. Vol. 22, No. 86. Pages 43-52
• Small, R.J. and M.J. Clark , 1976. Morphology
  and development of Medial Moraines Reply to N.
  Eyles. Journal of Glaciology. Vol. 17, No. 75.
  Pages 161-165.
• Vere, D.M. and D.I. Benn , 1989. Structure and
  Debris Characteristics of Medial Moraines in
  Jotunheimen, Norway Implications for Moraine
  Classification. Journal of Glaciology. Vol. 35,
  No. 120. Pages 276-280