Earth Systems & Resources Study Notes

EARTH SYSTEMS & RESOURCES

Unit Overview

  • This unit covers critical concepts regarding Earth's systems and resources.

  • Key Topics:

    • 4.1 Plate Tectonics

    • 4.2 Soil Formation and Erosion

    • 4.3 Soil Composition and Properties

    • 4.4 Earth's Atmosphere

  • Suggested Skills:

    • 2.C Explain relationships in environmental concepts illustrated visually.

    • 4B Identify methods of research design.

    • 4C Describe aspects of research methodology.

    • 2.A Describe visual representations of environmental concepts.

    • 1.C Explain environmental concepts in practical contexts.

  • Duration: Approximately 11-12 class periods.

4.1 - PLATE TECTONICS

  • Enduring Understanding: Earth's systems maintain a state of balance over time through interactions.

  • Learning Objective: Describe geological changes occurring at convergent, divergent, and transform plate boundaries.

The Formation & Structure of Earth

  • Formation Timeline: Earth formed approximately 4.6 billion years ago from cosmic dust in the solar system.

  • As Earth's molten material cooled, elements segregated by mass:

    • Heavier elements (e.g., iron) sank to the center.

    • Lighter elements (e.g., silica) rose to the surface, contributing to atmospheric gases.

  • The original elements and minerals present during formation are the same that exist today, with uneven global distribution creating resource availability disparities.

Geological Time Scale

  • Time since Earth's origin is divided into three eons:

    • The most recent eon, Phanerozoic, subdivided into three eras with 11 periods, ending with the Quaternary.

  • Epoch: A time period shorter than an era but longer than an age. The current epoch is the Holocene.

  • Structure: Age → Epoch → Period → Era → Eon.

Earth's Layering

  • Layers based on Chemical Composition:

    • Core: Innermost zone, composed mainly of iron and nickel.

    • Outer Core: Liquid layer.

    • Inner Core: Solid layer.

    • Mantle: Above the core; contains magma.

    • Crust: Outermost distinct layer of Earth.

  • Layers based on Physical Properties:

    • Lithosphere: Rigid outer layer encompassing the solid upper mantle and crust.

    • Asthenosphere: Semi-molten, ductile layer in the outer mantle.

    • Mesosphere: Part of the mantle between the lithosphere and outer core.

    • Outer Core: Liquid iron and nickel circulating; generates Earth's magnetic field.

    • Inner Core: Solid nickel and iron.

Convection and Hot Spots

  • Convection: Movement within a fluid where hotter, less dense material rises, and cooler, denser material sinks under gravity, transferring heat energy.

  • Hot Spot: Area where magma from the mantle breaches the lithosphere.

Earth’s Geologic Cycle

  • Three Major Processes:

    1. Tectonic Cycle: Build-up and breakdown of the lithosphere.

    2. Rock Cycle: Processes of formation, alteration, and destruction of rock.

    3. Hydrologic Cycle: Movement of water between lithosphere and atmosphere, aiding in weathering, erosion, deposition, and soil formation.

Plate Tectonics

  • Plate Tectonics Theory: Earth's lithosphere is divided into tectonic plates in constant motion.

  • Continental Drift Theory: Proposed by Alfred Wegener, suggesting continents have shifted over geological time from a supercontinent known as Pangaea.

  • Types of Plates:

    • Oceanic Plates: Dense, iron-rich crust mainly beneath oceans.

    • Continental Plates: Less dense materials predominantly beneath land masses.

Evidence of Continental Drift

  • Similar fossils and rock formations found on different continents support the theory of continental drift.

Tectonic Plate Boundaries

  • Convergent Boundary: Plates move toward each other, leading to collisions.

  • Divergent Boundary: Plates move apart, often forming new crust.

  • Transform Boundary: Plates slide past each other, causing friction.

Divergent Boundaries

  • Sea Floor Spreading: Formation of new ocean crust from rising magma.

  • Results include the creation of rift valleys and volcanic activity.

  • Examples: Iceland and the East African Rift.

Convergent Boundaries

  • Types:

    • Oceanic-Oceanic: Island arc formation.

    • Oceanic-Continental: Volcanic arc formation and associated earthquakes.

    • Continental-Continental: Formation of mountain ranges (e.g., Himalayas).

  • Subduction: One plate moves beneath another into the mantle, forming subduction zones leading to potential earthquakes and tsunamis.

Transform Fault Boundaries

  • Fault: Fracture in rock due to crustal movement, causing earthquakes.

  • Example: San Andreas Fault in California.

Consequences of Plate Movements

  • Plate movement can lead to geological events like volcanoes and earthquakes:

    • Majority of volcanoes are along subduction zones (80%).

  • The April 2010 eruption of Eyjafjallajökull caused significant disruptions to air traffic, halting over 107,000 flights due to ash clouds.

Seismic Waves

  • Seismic Waves: Energy waves traveling through Earth, caused by earthquakes or volcanic activities.

  • Types of Seismic Waves:

    1. Primary Waves (P-waves): Fastest.

    2. Secondary Waves (S-waves): Slower, more destructive.

    3. Surface Waves (Love and Rayleigh Waves): Cause ground deformation and damage.

  • Richter Scale: Measures magnitude of earthquakes; each whole number increase reflects a tenfold increase in amplitude and approximately 31.6 times more energy release.

Earthquake Impact

  • Epicenter: Point on the surface above where the earthquake occurs.

  • Seismic activities fluctuate based on energy release and accumulated pressure along faults.

  • Severity influenced by distance from the epicenter and ground composition.

Key Concepts Beyond Plate Movements

  • The Magnitude of earthquakes can significantly impact local populations and infrastructure following a seismic event.

4.2 - SOIL FORMATION & EROSION

  • Enduring Understanding: Earth's systems interact to maintain balance.

  • Learning Objective: Describe soil characteristics and formation.

Soil Formation

  • Soils result from the weathering, transport, and deposition of parent material.

  • Soil Horizons: Categorized by composition and organic content.

  • Soil stability contributes to water quality, filtering contaminants.

The Rock Cycle

  • Rock Cycle: Continual formation and destruction of rock, influencing soil creation.

  • Types of Rocks:

    1. Igneous: Formed from magma.

    2. Sedimentary: Formed from compressed sediments, preserving fossils.

    3. Metamorphic: Formed under heat and pressure.

Weathering Processes

  • Weathering: Break down of rocks through physical (mechanical) and chemical means.

  • Types of Weathering:

    • Physical Weathering: Breakdown via physical forces (e.g., ice wedging).

    • Chemical Weathering: Rock transformation through chemical reactions (e.g., acid rain).

Erosion & Deposition

  • Erosion: Removal of rock fragments through wind, water, and organisms.

  • Deposition: Accumulation of eroded materials.

  • High temperatures and rainfall can lead to nutrient-poor soil due to leaching.

Soil Importance

  • Soils support plant growth, filter water, and serve as habitats.

  • Ecosystem Services from Soil:

    • Water supply and purification

    • Organic waste recycling

    • Habitat provision for organisms

Factors Influencing Soil Formation

  1. Parent material: Influences soil characteristics.

  2. Climate: Types of climate affect soil types.

  3. Topography: Surface features influence soil formation.

  4. Organisms: Roots and microbial life affect soil composition.

  5. Time: Period of development impacts soil features.

Soil Horizons and their Characteristics

  • Soil forms layered horizons:

    • O Horizon: Organic matter (litter and humus).

    • A Horizon: Topsoil, rich in organic material.

    • E Horizon: Eluviation layer, leaching minerals.

    • B Horizon: Accumulation of nutrients and minerals.

    • C Horizon: Least weathered layer, resembles parent material.

    • R Horizon: Bedrock beneath all other layers.

Soil Composition & Properties

  • Water Holding Capacity: Varies among soil types, impacting land fertility.

  • Soil Texture: Based on proportion of sand, silt, and clay, affects permeability and porosity.

  • Soil Texture Triangle: Used for classifying soil based on mineral percentages.

Physical Properties of Soil

  • Mixture of organic matter, weathered rock, and inorganic materials (minerals, water, and gas).

  • Primary minerals classified by size: sand, silt, clay.

  • Permeability: Ability to transmit fluids; influences drainage.

  • Porosity: Volume of spaces between particles; affects water holding.

Biological Properties of Soil

  • Diverse organisms include fungi, bacteria, protozoans, and invertebrates.

  • Healthy soil has high organic matter for improved water holding capacity.

4.4 - EARTH'S ATMOSPHERE

  • Enduring Understanding: Earth's systems interact, resulting in balance.

  • Learning Objective: Describe atmospheric structure and composition.

Composition of the Atmosphere

  • Major Components:

    • Nitrogen (78%)

    • Oxygen (21%)

    • Argon (0.93%)

    • Carbon Dioxide (0.03%)

  • Each gas plays crucial roles in supporting life.

Atmospheric Layers

  • Composed of five layers differing in composition, density, and temperature:

    1. Troposphere: Closest to Earth, where weather occurs.

    2. Stratosphere: Contains the ozone layer, blocking harmful radiation.

    3. Mesosphere: Meteoroids burn up here.

    4. Thermosphere: Glows with solar energy; location of Northern Lights.

    5. Exosphere: Outermost layer, leading to outer space; satellite orbit layer.

Understanding Earth's Atmosphere

  • The atmosphere’s structure reflects its importance in regulating Earth's climate and supporting ecological systems.

  • Climate dynamics are influenced by temperature gradients and compositions of gases present in each layer.