GEOL 101 Study Notes

GEOL 101 Study Notes

Learning Objectives

  • Communication: Essential for understanding and relating scientific concepts.

  • Data Synthesis: Combining different data forms to arrive at a conclusion.

  • Quantitative Skills: Applying numerical skills for analysis and problem-solving.

  • Understanding Glacier Formation & Movement:

    • Glacier formation and movement are critical themes in geological studies.

    • Understand the causes of ice ages.

Glacier Formation

  • Four Conditions Necessary for Glacier Formation:

    1. Sufficiently Cold Local Climate: The climate must be cold enough during winter that snow does not completely melt in summer.

    2. Sufficient Snowfall: There must be enough snowfall so that a large accumulation of snow occurs.

    3. Gentle Slope: The surface where snow accumulates must have a gentle slope to prevent snow from sliding away due to avalanches.

    4. Protected Area: The snowfall area must be shielded from wind to prevent snow from blowing away.

Glacier Movement

  • Key Concepts in Glacier Movement:

    • Able to describe how glaciers accumulate and ablate (lose) mass.

    • Understanding glacier advance and retreat, along with how to draw and interpret conceptual models of glaciers.

Conceptual Models of Glaciers

  • Important Zones:

    • Zone of Accumulation: Area where snow falls and accumulates as ice.

    • Zone of Ablation: Area where parts of the glacier are lost through sublimation, calving, and melting, indicating glacier retreat.

    • Equilibrium Line: Boundary between the zone of accumulation and the zone of ablation.

  • Defined Processes:

    • Sublimation: The process through which a solid transforms directly into a gas, without becoming liquid, often contributing to mass loss in glaciers.

    • Calving: The process by which chunks of ice break off from the edge of a glacier to form icebergs.

Glacier Dynamics

  • Glacial Advance:

    • Occurs when there is a higher accumulation of snow leading the glacier to advance.

    • Associated with a lower equilibrium line and less ablation.

  • Glacial Retreat:

    • Happens when ablation exceeds accumulation; the glacier retreats.

    • Characterized by a higher equilibrium line and increased ablation.

Ice Ages

  • Definition and Relevance:

    • An ice age is a prolonged period of cooling with notable glaciation events affecting a significant portion of the Earth's surface.

  • Types of Permafrost:

    • Continuous Permafrost: Found in regions with consistent cold conditions.

    • Discontinuous Permafrost: Occurs in areas where the permafrost is not uniformly present.

    • Alpine Permafrost: Located in mountainous regions.

Impacts of Glaciation

  • Topographic Changes: Glaciers significantly shape the modern topography, such as creating U-shaped valleys from previously V-shaped streams.

  • Significant Features Post-Glaciation:

    • U-shaped valleys, horns, cirques, hanging valleys, and truncated spurs are common formations resulting from glacial actions.

    • Striations left behind indicate past glacial movements.

Causes of Ice Ages

  1. Long-Term Causes:

    • Influences span millions of years, primarily from plate tectonics and changes in atmospheric carbon dioxide levels.

  2. Short-Term Causes:

    • Variations such as orbital changes, including:

      • Eccentricity: The change in Earth's orbital shape between more circular and elliptical, with cycles approximately every 100,000 years.

      • Axial Tilt: Changes in the angle of tilt affecting solar radiation absorption, with roughly a 41,000-year cycle.

      • Precession: The wobble of Earth affecting climate over a 23,000-year cycle.

      • Albedo Effect: The presence of high albedo surfaces reflecting sunlight, affecting global temperatures and potentially leading to cooling.

  • Importance of Understanding Ice Ages:

    • Reconstructing Earth’s climatic history is essential for defining glacial periods and understanding their impact on current landscapes.