Weathering, Erosion, and Earth's Layers

Study Notes

Weathering: The process of breaking down and corroding solid rocks into sediments.
Types of Weathering:
- Physical (Mechanical): Breakdown of rocks without chemical change (e.g., freeze-thaw, thermal expansion)
- Chemical: Breakdown of rocks through chemical reactions (e.g., oxidation, hydrolysis, carbonation)
Examples of chemical weathering:
- Dissolution: Minerals dissolving in water
- Oxidation: Minerals reacting with oxygen, forming oxides (e.g., rust)
- Hydration: Minerals absorbing water, causing expansion and weakening.
Erosion: The process of moving sediments from one location to another.
Main forces of erosion:
- Water (rivers, rainfall, runoff)
- Wind (sand dunes)
- Ice (glaciers, ice sheets)
- Coastal forces (waves, tides)

Earth's Layers:
- Inner Core: Solid sphere, mainly iron and nickel
- Continental Crust: Approximately 35-70 km thick
- Lithosphere: About 100 km thick, composed of the crust and upper mantle
- Asthenosphere: Plastic, partially molten layer beneath the lithosphere
Plate Tectonics:
- Alfred Wegener's Continental Drift Theory (1912): Continents were once a single landmass (Pangaea) and have drifted apart
- Seafloor Spreading: Creation of new oceanic crust at mid-ocean ridges, pushing tectonic plates apart.
- Henry Hess: Proposed the theory of seafloor spreading
- Mid-Ocean Ridges: Formed as a result of seafloor spreading
- Geomagnetic Reversals: Occur every 200,000-300,000 years

Folding:
- Anticline: Convex upward fold, oldest rocks at the core
- Syncline: Concave upward fold, youngest rocks at the core
- Monocline: Step-like fold in rock strata
- Plunging Fold: Fold with a non-horizontal axis
Faulting:
- Normal Fault: Block above the fault moves downward relative to the block below
- Reverse Fault: Block above the fault moves upward relative to the block below
- Strike-Slip Fault: Horizontal sliding of rock blocks

Magma and Magma Chambers:
- Components: Gases, minerals, and liquid rock
- Magma Chamber: Stores magma before eruption
- Solidification: Magma cools and crystallizes into igneous rock
Volcanic Activity:
- Importance of study: Provides insights into volcanic activity and crust formation
- Effects on environment: Volcanic eruptions significantly alter landscapes and impact climate

Erosion and Deposition:
- Deposition: Builds up layers of sediment, creating new landforms
- Landform Formation: Trenches form due to tectonic plate interactions (e.g., subduction)
Plate Boundaries:
- Transform Boundaries: Earthquakes occur due to stress buildup as plates grind together
- Continental-Continental Boundaries: Create large mountain ranges through the crumpling and thickening of the crust
- Oceanic-Continental Boundaries: Result in subduction of the denser oceanic plate beneath the less dense continental plate
- Divergent Boundaries: Associated with seafloor spreading and creation of new oceanic crust.