Unit 4: Earth Systems

• Earth's Structure

  1. Core
  2. Mantle
  3. Asthenosphere
  4. Lithosphere
  5. Crust
• Core

  • The dense mass of solid nickel, iron, and radioactive elements that holds massive amounts of heat
• Mantle

  • Liquid layer of magma surrounding core, kept liquified by intense heat from core
• Asthenosphere

  • The solid, flexible outer layer of the mantle, beneath the lithosphere
• Lithosphere

  • The thin, brittle layer of rock ontop of mantle that is broken into tectonic plates
• Crust

  • The very outer layer of the lithosphere, earth's surface
• Divergent Plate Boundaries

  • Plates move away from each other
  • Rising magma plumes from mantle force plates apart

  
• Convergent Plate Boundary

  • Plates move towards each other
  • This leads to subduction (one plate being forced beneath another)
• What do convergent boundaries form?

  Mountains, island arcs, and volcanoes
• What do divergent boundaries form?

  Mid-oceanic ridges, volcanoes, sea-floor spreading, and rift valleys on land
• Transform Fault Plate Boundary

  • Plates slide past each other in opposite directions
• What is most common with transform fault plate boundaries?

  Earthquakes
• Convection Cycles (Divergent)

  1. Magma heated by earth's core rises toward lithosphere
  2. Rising magma cools and expands, forcing ocean plates apart
  3. Magma cools and solidifies into new lithosphere
  4. Spreading magma forces oceanic tectonic plate into continental (subduction zone)
• Subduction Zone: Oceanic-Oceanic

  • One plate subducts underneath the other
  • Forces magma up to the lithosphere surface, forming mid-ocean volcanoes—an island arc.
  • Off-shore trench
• Subduction Zone: Oceanic-Continental

  • Dense oceanic plate subducts beneath continental plate and melts back into magma
  • Forces magma up to the lithosphere surface
  • Coastal mountains (Andes), volcanoes on land trenches, tsunamis
• Subduction Zone: Continental-Continental

  • One plate subducts underneath the other, forcing the surface crust upward (mountain)
  • Ex. Himalayas
• Transform Fault Boundary

  • Occurs when rough edges get stuck in each other
  • Pressure builds as plates keep sliding, but edges stay stuck
  • When stress overcomes the locked fault, plates suddenly release, slide past each other, and release energy that shakes the lithosphere
• Ring of Fire

  • A pattern of volcanoes all around Pacific plate
  • Offshore Island Arcs (Japan)
  • Convergent plate boundaries usually to lead to volcanoes
• Transform Faults

  • Likely location of earthquakes
  • Ex. Haiti
• Hotspots

  • Areas of especially hot magma rising up to lithosphere
  • Divergent or volcanoes
• • Soil is a mix of geological (rock) and organic (living components)
  • Sand, silt, clay
  • Humus: main organic part of soil
  • Nutrients: ammonium, phosphates, nitrates
  • Water and air
  • Living organisms
• Importance of Soil: Plants

  • Anchors roots of plants and provides water, shelter, nutrients for growth
• Importance of Soil: Water

  • Filters rainwater and runoff by trapping pollutants in pore spaces and plant roots
  • Clean water enters groundwater aquifers
• Importance of Soil: Nutrient Recycling

  • Home to decomposers that break down organic matter and return nutrients to the soil
• Importance of Soil: Habitat

  • Provides habitat for organisms like earthworms, fungi, bacteria, moles, and slugs
• Weathering

  • Breakdown of rocks into smaller pieces
• Types of Weathering

  • Physical
  • Wind, air, freezing/thawing of ice
  • Biological
  • Roots of trees crack rocks open
  • Chemical
  • Acid rain, acid from moss/lichen
• • Weathering of rock leads to soil formation
  • Broken into smaller and smaller pieces
  • Carried away and deposited by erosion
• Erosion

  • Transport of weathered rock fragments by wind and rain
  • Carried to a new location and deposited (deposition)
• Soil Formation Below

  • Weathering of parent material produces smaller and smaller fragments that make up geological/inorganic part of soil
  • Sand, silt, clay and minerals
• Soil Formation Above

  • The breakdown of organic matter adds humus to the soil
  • Erosion deposits soil particles from other areas, adding soil
• Factors Affecting Soil Formation

  • Parent material
  • Topography
  • Climate
  • Organisms
• Soil Formation Factors: Parent Material

  • Soil pH and nutrient material
  • Ex. limestone has more calcium
• Soil Formation Factors: Topography

  • Steep slope leads to too much erosion and slows down soil formation
  • More level ground leads to deposition and faster formation
• Soil Formation Factors: Climate

  • Warmer area leads to faster breakdown of organic matter
  • Colder area leads to slower breakdown of humus
  • More precipitation leads to more weathering, erosion, deposition
• Soil Formation Factors: Organisms

  • Soil organisms like bacteria, fungi, and worms break down organic matter
• Soil Horizons

  • O-Horizon
  • A-Horizon
  • B-Horizon
  • C-Horizon
• O-Horizon

  • A layer of organic matter (plant roots, dead leaves, animal waste, etc.) on top of soil
  • Provides nutrients and limits H20 loss to evaporation
• A-Horizon

  • Called topsoil
  • A layer of humus (decomposed organic matter) and minerals from parent material
  • A-Horizon has most biological activity (earthworms, soil, microbes) breaking down organic matter to release nutrients
• B-Horizon

  • Called subsoil
  • A lighter layer below topsoil, mostly made of minerals with little to no organic matter
  • Contains SOME nutrients