Unit 4: Earth Systems and Resources

Topic 4.1: Plate Tectonics

• Convergent Boundaries

  • Result in mountains, island arcs, earthquakes, and volcanoes.

• Divergent Boundaries

  • Cause seafloor spreading, rift valleys, volcanoes, and earthquakes.

• Transform Boundaries

  • Primarily associated with earthquakes.

• Mapping Plate Boundaries

  • Global distribution maps indicate the locations of volcanoes, island arcs, earthquakes, hot spots, and faults.

• Earthquake Mechanism

  • Occur when stress accumulates and exceeds the capacity of a locked fault, releasing stored energy.

Plate Boundaries Around the World

• Major tectonic plates include:

  • Eurasian Plate

  • North American Plate

  • Pacific Plate

• 'Ring of Fire': A zone of high seismic and volcanic activity encircling the Pacific Ocean, notable for numerous active volcanoes.

Different Types of Plate Boundaries

• Type of Margin

  • Divergent: Spreading - constructive (new oceanic lithosphere created).

  • Convergent: Subduction - destructive (oceanic lithosphere destroyed).

  • Transform: Lateral sliding - conservative (no new or old plate consumption).

• Topography Effects:

  • Divergent: Ridge/Rift

  • Convergent: Trench

  • Transform: No major topographical effects.

• Volcanic Activity

  • Divergent and convergent boundaries can lead to significant volcanic activity; transform boundaries generally do not.

Mechanisms of Plate Boundaries

• Divergent Boundary: Plates move apart, creating new lithosphere at mid-ocean ridges.

• Convergent Boundary: One plate sinks below another (subduction). Landforms features such as volcanic arcs and trenches.

• Transform Boundary: Plates slide past each other, leading to earthquakes along vertical faults.

Topic 4.2: Soil Formation and Erosion

• Soil Formation Process

  • Occurs through weathering, transportation, and deposition of parent material.

• Soil Horizons

  • Classified based on composition and organic material presence.

• Erosion

  • Soil can be eroded by wind or water, emphasizing the importance of soil conservation for water quality.

Soil Particles and Size

• Particle Sizes:

  • Sand: 0.05mm - 2mm

  • Silt: 0.002mm - 0.05mm

  • Clay: <0.002mm

Soil and Rock Particle Sizes

• Rock fragments and sizes ranging from clay to boulders.

• Unified Sieve standard sizes range used to classify soil types.

Soil Horizons Profile

• A (Surface Horizon): Organic material (humus)

• A Horizon: Topsoil; B Horizon: Subsoil; C Horizon: Partially weathered parent material; R Horizon: Bedrock.

Topic 4.3: Soil Composition and Properties

• Water Holding Capacity: Varies with soil type, influencing productivity and fertility.

• Properties Affecting Soil:

  • Particle size impacts porosity, permeability, and fertility.

• Various tests available for chemical and physical properties of soil aiding agricultural decisions.

• Soil Texture Triangle: Diagram for classifying soil types based on clay, silt, and sand ratios.

Soil Characteristics

• Porosity: Amount of pore space in soil.

• Permeability: Rate water infiltrates into soil.

• Fertility: Measurement of soil nutrient content.

Topic 4.4: Earth’s Atmosphere

• Composition: Major gases present in the atmosphere, each with specific abundance.

• Layers of the Atmosphere: Differentiated by temperature gradients:

  • Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere.

Topic 4.5: Global Wind Patterns

• Formation: Wind patterns driven by solar radiation intensity differences at the equator and influenced by the Coriolis effect.

Topic 4.6: Watersheds

• Watershed Characteristics: Defined by area, length, slope, soil, vegetation types, and divides.

Topic 4.7: Solar Radiation and Earth’s Seasons

• Solar Radiation: Main energy source, varies with season and latitude.

• Intensity: Highest at the equator; decreases towards poles.

• Seasonal Variation: Influenced by Earth's axial tilt affecting daylight duration and seasonal changes.

Topic 4.8: Earth’s Geography and Climate

• Influencing Factors: Weather and climate affected by solar energy, geological, and geographic features.

• Rain Shadow Effect: A drier region created when a higher elevation area blocks precipitation.

Topic 4.9: El Niño and La Niña

• Phenomena Overview: Linked to ocean surface temperature changes impacting global weather patterns.

• Influences vary by geographical location.