Notes on Glaciation Processes and Landforms

Glaciation Overview

  • Definition: Glaciation refers to periods when Earth is entirely covered with ice and glaciers, significantly altering landscapes.
  • Ice Age: Lasted over 2 million years, ending approximately 10,000 years ago, leading to the current Holocene interglacial period.
  • Global Warming Impact: Although human-induced global warming may affect the timing of future ice ages, it's unlikely to occur in the next century.

Key Points About Glaciers

  • Glaciers are slow-moving rivers of ice forming where snowfall surpasses melting over years.
  • They are the largest freshwater source and are found in polar and mountainous areas (e.g., Antarctica, Greenland).
  • Glacier formation: Snow compresses into firn, leading to glacier ice.
Glacier Zones
  1. Zone of Accumulation: Area of high elevation where snowfall exceeds melting.
  2. Ablation: The loss of ice through melting and iceberg calving.
Types of Glaciers
  1. Valley Glaciers: Flow down valleys in mountainous regions.
  2. Continental Ice Sheets: Massive ice sheets, e.g., those in Antarctica and Greenland.

Causes of Ice Ages

  • Triggered by changes in Earth's solar relationship:
    1. Earth's Orbit: Variations causing cooling.
    2. Tilt of Earth's Axis: Affects climate.
    3. Earth's Wobble: Influences sunlight distribution.

Glacial Erosion Processes

  • Plucking: Glaciers scrape the valley floors and incorporate rocks.
  • Abrasion: Embedded rocks grind against the valley surfaces, reshaping the terrain.

Glacial Transportation

  • Moraine: Material moved and deposited by glaciers.
  • Types of Glacier Movement:
    • Basal Sliding: Meltwater at the base provides lubrication.
    • Internal Flow: Ice crystal deformation allows movement without melting.
Factors Affecting Glacial Erosion
  1. Ice Thickness
  2. Geology and Topography
  3. Gradient of slope

Landforms of Glacial Erosion

Cirque
  • A bowl-shaped depression marking a glacier's origin; contains tarns post-melt.
Arête
  • A narrow ridge formed between two eroded cirques.
Pyramidal Peak
  • A pointed peak formed by multiple eroding cirques.
U-Shaped Valley
  • Transformed from V-shape by glacial action; steep sides and flat floor.
Hanging Valleys and Ribbon Lakes
  • Small U-shaped valleys perched above larger ones; long, narrow lakes formed in glaciated areas.

Processes of Glacial Deposition

  • Deposition: Material left behind when glaciers melt, known as glacial drift.
  • Till: Unsorted material deposited directly by ice.
Landforms of Glacial Deposition
  1. Moraines: Debris piles from glaciers.
  2. Drumlins: Oval-shaped hills formed from boulder clay.
  3. Erratics: Rocks transported by glaciers that differ from local geology.
Fluvio-Glacial Deposits
  • deposits made by meltwater streams; stratified and sorted.
    1. Eskers: Winding ridges formed by meltwater streams.
    2. Outwash Plains: Flat areas containing sorted deposits.
    3. Kames: Piles of sediment deposited by meltwater.
    4. Kettle Holes: Depressions left by melting ice blocks, often forming lakes.