MITIHANI POPOTE EXAMINATION SERIES GLACIATION PROCESSES AND FEATURES TEST (With answers)

GLACIATION PROCESSES AND FEATURES

1. Explain the theories which aspire to explain the occurrence of glaciers in various parts of the world

   Several scientific theories attempt to explain the distribution and formation of glaciers worldwide:

   1. Astronomical Theory (Milankovitch Cycles)

   • Eccentricity: Changes in Earth's orbital shape (100,000-year cycle)
   • Obliquity: Variations in axial tilt (41,000-year cycle)
   • Precession: Wobble in Earth's rotation (26,000-year cycle)
   • Impact: Affects solar radiation distribution and intensity

   2. Plate Tectonics Theory

   • Continental drift positions landmasses at high latitudes
   • Mountain building creates high-altitude snow accumulation zones
   • Ocean current changes affect heat distribution
   • Example: Antarctic glaciation began when continent moved over South Pole

   3. Atmospheric Composition Theory

   • Greenhouse gas variations (CO₂, methane) affect global temperatures
   • Volcanic activity can trigger cooling via aerosol emissions
   • Industrial revolution impacts on modern glaciers

   4. Albedo Feedback Theory

   • Ice-snow reflectivity increases as glaciers expand
   • Positive feedback loop accelerates cooling
   • Explains rapid glacial advances during ice ages

   [Diagram showing Milankovitch cycles and their impact on glaciation]

   Current consensus: Most scientists believe glacial periods result from complex interactions between astronomical factors, atmospheric composition, and Earth's geography.

2. Explain the features due to glacier erosion in highland (Alpine) areas

   Alpine glaciers create distinctive erosional landforms through plucking and abrasion:

   Valley Features:

   • U-shaped valleys: Steep-sided, flat-bottomed valleys carved by glacier movement
     [Cross-section comparing V-shaped river valley to U-shaped glacial valley]
   • Hanging valleys: Tributary glaciers left elevated above main valley
     Create spectacular waterfalls like Yosemite Falls
   • Cirques: Bowl-shaped depressions at glacier origins
   • Arêtes: Sharp ridges between adjacent cirques
   • Horns: Pyramid-shaped peaks formed by multiple cirques (e.g., Matterhorn)

   Rock Features:

   • Roche moutonnée: Asymmetrical rock hills with smooth up-ice and jagged down-ice sides
   • Striations: Parallel scratches on bedrock from embedded rocks in glacier base
   • Glacial polish: Smooth rock surfaces created by fine abrasion
   • Truncated spurs: Cliff-like ends of ridges cut off by glacier movement

   Feature	Formation Process	Example Locations
   Fjords	Glaciated valleys flooded by sea	Norway, New Zealand
   Tarns	Lakes in cirque basins	Alps, Rocky Mountains
   Cols	Passes between adjacent cirques	Mountain ranges worldwide

3. How useful are glacial erosional and depositional features to human beings

   Benefits of Glacial Erosional Features:

   • Tourism: Spectacular landscapes attract visitors (e.g., Yosemite, fjords)
   • Water storage: Cirque lakes and U-shaped valleys form natural reservoirs
   • Fertile soils: Ground rock flour enriches agricultural land
   • Transportation: Glacial valleys provide natural routeways
   • Hydropower: Steep valleys ideal for dam construction

   Benefits of Glacial Depositional Features:

   • Agriculture: Till plains provide fertile soils (e.g., American Midwest)
   • Construction materials: Sand and gravel from outwash plains
   • Groundwater reservoirs: Porous glacial deposits store water
   • Mineral deposits: Placer deposits in glacial sediments
   • Landform diversity: Creates varied habitats for ecosystems

   Feature	Human Use	Economic Value
   Moraines	Soil fertility, landscaping	High agricultural value
   Eskers	Road foundations, aggregate	Construction industry
   Kettle lakes	Recreation, fisheries	Tourism revenue

   Cultural significance: Many glacial landscapes hold spiritual and historical importance for indigenous peoples worldwide.

4. Discuss the features due to glacial deposit

   Glaciers deposit various landforms as they melt, classified by deposition method:

   Direct Glacial Deposits (Till):

   • Moraines: Ridges of unsorted glacial debris
     [Diagram showing different moraine types in a glacial valley]
   • Drumlins: Streamlined hills of compacted till
   • Erratics: Large boulders transported far from source
   • Till plains: Extensive flat areas of glacial deposits

   Meltwater Deposits (Stratified Drift):

   • Outwash plains: Sandur deposits beyond glacier terminus
   • Eskers: Winding ridges of sorted sediment from subglacial streams
   • Kames: Steep-sided mounds of stratified drift
   • Kettle lakes: Depressions from buried ice blocks melting
   • Varves: Annual layers in glacial lake sediments

   Deposit Type	Sorting	Typical Composition
   Till	Unsorted	All particle sizes mixed
   Stratified drift	Sorted	Layered by size

   Scientific value: Glacial deposits provide records of past climate conditions and ice movement directions.

5. What negative effects does glaciation have on Earth

   Ecological Impacts:

   • Habitat destruction: Crushing of ecosystems under ice sheets
   • Species displacement: Forced migration of flora and fauna
   • Sea level changes: Coastal flooding or exposure during cycles

   Geological Hazards:

   • Glacial outburst floods: Sudden release of meltwater (jökulhlaups)
   • Isostatic rebound: Earth's crust rising after ice melt causes earthquakes
   • Permafrost melting: Releases greenhouse gases and destabilizes land

   Human Impacts:

   • Landscape alteration: Destruction of pre-glacial landforms
   • Resource limitations: Ice cover makes mineral extraction difficult
   • Infrastructure damage: Glacial movement destroys human constructions
   • Modern concerns: Retreating glaciers threaten water supplies

   [Diagram showing impacts of glacial retreat on sea levels and ecosystems]

   Long-term effects: Past glaciations have permanently altered global drainage patterns and continental configurations.

6. Classify moraines

   Moraines are classified by their position relative to the glacier:

   Moraine Type	Location	Characteristics
   Lateral	Along glacier sides	Ridges parallel to flow direction
   Medial	Between glacier tributaries	Formed by merging lateral moraines
   Terminal	At glacier terminus	Marks maximum advance position
   Recessional	Behind terminal moraine	Marks temporary standstill positions
   Ground	Beneath glacier	Irregular blanket of till
   Push	At glacier front	Material bulldozed during advance

   [Diagram showing moraine types in relation to glacier position]

   Special types: Washboard moraines (small parallel ridges) and hummocky moraines (irregular mounds) form under specific glacial conditions.

7. Glacial regions are not necessarily bad - discuss

   Ecological Benefits:

   • Freshwater storage: Glaciers are Earth's largest freshwater reservoirs
   • Unique ecosystems: Support specialized flora and fauna
   • Climate regulation: Reflect solar radiation and influence ocean currents

   Human Benefits:

   • Water supply: Seasonal melt provides water for billions
   • Renewable energy: Glacial rivers feed hydroelectric projects
   • Scientific value: Ice cores preserve climate records
   • Economic resources: Mineral deposits and fertile soils
   • Tourism: Glacier tourism supports local economies

   Geological Benefits:

   • Landscape diversity: Create varied topography
   • Soil formation: Ground rock produces fertile till
   • Resource concentration: Deposits valuable minerals

   Balanced view: While glaciation presents challenges, it also provides essential ecosystem services and resources that benefit both nature and human societies.

8. Contrast the effects of glaciation on highland and lowland areas

   Aspect	Highland Areas	Lowland Areas
   Dominant Process	Erosion predominates	Deposition predominates
   Landforms Created	Cirques, arêtes, horns, U-shaped valleys	Till plains, drumlins, eskers, moraines
   Glacier Type	Alpine/valley glaciers	Ice sheets/continental glaciers
   Movement	Channeled by topography	Unconstrained radial flow
   Erosional Features	Deep valleys, truncated spurs	Scoured bedrock, roche moutonnée
   Depositional Features	Lateral/medial moraines	Terminal moraines, outwash plains
   Human Impact	Creates dramatic scenery	Forms fertile agricultural lands

   [Diagram comparing highland and lowland glacial impacts]

   Key difference: Highland glaciation is primarily erosional, creating dramatic relief, while lowland glaciation is primarily depositional, smoothing and covering the landscape.

9. Explain the types of glaciers

   Glaciers are classified based on their size, shape, and location:

   Glacier Type	Description	Examples
   Ice sheets	Massive continental-scale glaciers (>50,000 km²)	Antarctica, Greenland
   Ice caps	Smaller versions of ice sheets (<50,000 km²)	Vatnajökull (Iceland)
   Valley glaciers	Confined to mountain valleys	Mer de Glace (France)
   Piedmont glaciers	Spread out at mountain bases	Malaspina (Alaska)
   Cirque glaciers	Small glaciers confined to bowl-shaped depressions	Common in Rockies, Alps
   Tidewater glaciers	Terminate in ocean water	Hubbard Glacier (Alaska)
   Ice shelves	Floating extensions of ice sheets	Ross Ice Shelf

   Special Glacier Types:

   • Rock glaciers: Ice-cemented rubble that flows slowly
   • Hanging glaciers: Cling to steep mountain slopes
   • Reconstituted glaciers: Form from ice avalanches
   • Ice fields: Extensive areas of interconnected glaciers

   [Diagram showing different glacier types and their locations]

   Current changes: Many glacier types are retreating rapidly due to climate change, with significant impacts on water resources and sea levels.