Surficial Processes: Glacial and Eolian (Desert)

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Surficial Processes Glacial and Eolian (Desert)
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Environmental Implications of Glacial and Eolian
Processes

• Glacial
• Active processes generally less important than
  resulting materials and landforms
• Main exception Permafrost
• Explain?
• Eolian Wind/Deserts
• Active process and resulting materials are
  important
• Explain?

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Environmental Implications of Glacial and Desert
Systems Examples

• Processes Important for land use
• Landforms Physical characteristics important for
  human use (e.g., stability)
• Represent response (feedback) mechanisms to
  climatic changes
• Evidence/(Indicators of environmental change) for
  past and future changes in the global environment
  e.g., climate
• Coupled with other processes (e.g., plate
  tectonic, volcanism, atmospheric) affects other
  systems and processes (e.g., biogeochemical,
  surficial, etc.)

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Surficial Processes and Landforms Associated with
Ice and Wind

• Landforms environmentally sensitive areas
• Coastal, desert, arctic, subarctic
• Effects of ice and wind on rocks and landforms
• Environmental problems associated with wind and
  ice

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Ice Glaciation

• Glaciers (Land-bound) masses of moving ice
• Cover about 10 of earth
• Accounts for lt2 of earths water (w/ other forms
  of ice)
• Types
• Continental Cover large areas of land
• Alpine Confined to mountain valleys
• Both types are associated with distinctive
  erosional and depositional processes and
  resulting landform features
• Permafrost

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Continental Glaciation Landforms

• Erosional
• Expansive areas of exposed, eroded, flattened,
  polished bedrock
• Kettles/pothole lakes
• Depositional Expansive areas/fronts of deposition
• Morain highly variable, loose, jumbles of eroded
  material (typically unstable?)
• Drumlins
• Eratics
• Loess (windblown, very fine glacial silt)

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Drumlin
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Extent of glacial ice sheet in North America
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Alpine Glacial Landforms

• Erosional
• U-Shaped valleys
• Fjiords
• Horns, cirques, aretes
• Depositional
• Various types of till/morain

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Permafrost

• Permafrost Permanently frozen ground
• Underlies 20 of worlds land area
• Types
• Continuous Predominantly frozen all the time
• Discontinuous Areas of thawed ground in areas of
  predominantly frozen ground
• Potential for perturbation from human activities
• Examples?

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Environmental Significance

• Building/engineering challenges associated with
• Glacial deposits landforms
• Permafrost
• Environmental implications of man-made
  perturbations in permafrost areas
• Distribution physical characteristics of areas
  affected by glaciation
• Till/Morain vs. bedrock
• Groundwater implications
• Episodic effects
• Hubbard Glacier example

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Arid Environments
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Wind

• Simultaneous erosion and deposition
• Dunes
• Mass transport/deposition of sand close to the
  ground
• Dune type dependent on wind characteristics
• Physical Characteristics Loose, porous, variable
• Negative implications for flora/agriculture??
• Loess
• Fine-grained material carried up to thousands of
  meters in altitude
• Associated with expansive Dust storms (100s km
  in diam.)
• Found in specific geographic locations
• Highly susceptible to erosion
• Variable stability (e.g., for foundations, etc.)
• Can be good for agriculture

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• Dune characteristics vary with conditions
• Recognition/appreciation is important
• Memorization of the types details isnt (for
  this class)

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Environmental Implications of Eolean Deposits
Processes

• Loess hazardous foundations
• Problems of migrating sand, silt (e.g., expensive
  construction maintenance for highways,
  buildings, hydraulic structures
• Implications for geography, climate in geologic
  past
• Implications of desertification, global warming
  or cooling on the environment (later)

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Section Summary

• Recent (geologically) continental glaciation
  produced a variety of earth materials
• Widespread
• have implications for planning, design, building
• Permafrost
• environmentally sensitive
• Requires specialized engineering to prevent
  adverse effects
• Windblown sand, silt, dust
• Widespread
• Concentrated in specific areas (coasts, interior,
  rivers)
• Loess potential foundation problems/agricultural
  benefits
• Sand Dunes (Migrating Stabilized)
• Implications for construction maintenance of
  highways, buildings, hydraulic structures

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Other Things to Remember

• Erosional AND depositional implications of
  glacial and eolian processes
• Some of the more important examples
• Landforms
• Physical properties of e.g., till, loess
• Where do these types of materials occur
  (geographic distribution)
• Recognition (general) of landforms/materials
• Environmental implication for
• The past
• The present
• The future

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