Weathering Quiz

Weathering

• Physical weathering breaks down rocks without changing their chemical composition.
  • Frost wedging: Water freezes in cracks, expands, and breaks the rock.
  • Thermal expansion: Repeated heating and cooling causes rocks to expand and contract, leading to fractures.
  • Abrasion: Rocks and sediment grind against each other, wearing down surfaces.
  • Exfoliation: Layers of rock peel away due to pressure release or thermal stress.
• Chemical weathering breaks down rocks through chemical reactions that alter their mineral composition.
  • Hydrolysis: Water reacts with minerals to form new minerals and soluble salts.
  • Oxidation: Oxygen reacts with minerals, especially iron, to form oxides that weaken the rock.
  • Carbonation: Carbon dioxide in water forms carbonic acid, which reacts with minerals like limestone, dissolving them.
  • Solution: Minerals dissolve directly into water, especially those susceptible to acids.

Biological Weathering

• Breakdown of rocks by biological activities.
• Examples:
  • Root expansion: Plant roots grow in cracks, expand, and break rocks.
  • Lichen and moss: Produce acids that chemically weather rocks.
  • Animal activity: Burrowing animals disturb rock structure, leading to mechanical breakdown.

Erosion

• The process that wears away Earth’s surface by wind, water, or ice.
• It moves rock debris or soil from one place to another.
• Agents of erosion:
  • Water: Rivers, steams, and rain erode rocks and soil.
  • Wind: Transports fine particles, especially in arid regions.
  • Ice: Glaciers erode large amounts of rock and soil.
  • Gravity (Mass Wasting): Landslides and rock faults occur as gravity pulls loose material downslope.

Transportation

• Movement erodible material from one place to another.
• Natural forces like wind, water, and ice transport sediments, carrying them away from their original location.

Continental Drift

• Idea that continents move freely over Earth’s surface, changing positions relative to one another.
• Early evidence:
  • Geographic fit of continents: Africa and South America seem to fit together.
  • Similar fossils: Mesosaurus fossils found in different regions and continents.
  • Coal seams: Found in polar regions, suggesting a different past position of continents.
  • Matching mountain ranges: Similar rock layers and types across oceans.
  • Glacial deposits: Found in tropical and desert regions, indicating that continents shifted to different climates.

Seafloor Spreading

• Explains how new oceanic crust is created at mid-ocean ridges and destroyed at deep ocean trenches.
• Hess Hypothesis: Seafloor spreading is driven by deep mantle convection.
• Supporting evidences:
  • World seismicity: Earthquake distribution matches plate boundaries.
  • Volcanism: Volcanoes are found along some plate boundaries.
  • Age of sea floor: Youngest sea floors found at mid-ocean ridges; older sea floor farther away.
  • Paleomagnetism: Minerals in the ocean floor record the alignment of magnetic fields surrounding oceanic ridges.
  • Heat flow: Heat flow through bottom sediments is higher over mid-ocean ridges.

Plate Tectonics

• Combines continental drift and seafloor spreading.
• Earth’s surface is divided into large, mobile slabs of rock called plates.
• Plate boundaries: Where plates interact.
  • Divergent boundaries: Plates move apart, creating new crust (seafloor spreading).
  • Convergent boundaries: Plates collide.
    • Oceanic-oceanic convergence: One plate subducts beneath the other, forming volcanic island arcs.
    • Oceanic-continental convergence: Oceanic plate subducts beneath the continental plate; forms an active continental margin.
    • Continent-continent convergence: Plates collide and crumple, but neither subducts.
  • Transform boundaries: Plates move horizontally past each other.

Geological Mapping

• Crucial for understanding the structure and composition of the Earth.
• Used to identify reservoir rock units, understand trap structures, assess reservoir characteristics, and plan drilling operations.
• Methods:
  • Remote sensing and aerial imagery: Provide broad-scale geological patterns and structural features.
  • Geophysical methods: Seismic surveys, ground-penetrating radar, and magnetic surveys provide information about the subsurface.
  • GIS and digital mapping: Allow geologists to store, manipulate, and analyze geospatial data.
  • Compass/Clinometer: Used for determining direction and measuring inclination.
  • Geological Hammer: Tool for collecting rock samples.
  • Handheld Lens: Used for initial analysis of rock samples.

Test your knowledge on the processes of weathering, including both physical and chemical weathering methods. Understand key concepts like frost wedging, abrasion, hydrolysis, and oxidation. This quiz will challenge your understanding of how rocks break down over time.