Review

• Earth's Composition


  Core, Mantle, and Crust are divisions based on composition
• Core


  • Mostly iron metal
• Mantle


  • Hot and represents about 68 percent of Earth's mass
• Crust


  • Makes up less than 1 percent of Earth, consisting of oceanic crust and continental crust, continental crust is often more Felsic rock
• INGE LEHMANN discovered the Earth's Composition
• Layers of the Earth

  • Crust
  • Mantle
  • Outer core
  • Inner core
• Crust


  • Thin outer layer
• Mantle


  • Thickest layer, made up of Magma
• Magma


  Semi-molten outer core layer which surrounds the inner core
• The Earth is composed of several distinct layers, each with its own unique properties and composition
• Percentage composition of the Earth

  • Iron (35 percent)
  • Oxygen (30 percent)
  • Silicon (15 percent)
  • Magnesium (13 percent)
• Earth has existed for 4.543 billion years
• Temperature


  • Influences how quickly atoms, molecules, or organisms move
  • Low temperature slows down chemical reactions, produces ice
  • High temperature breaks down important biological molecules
  • Radiogenic heat is heat emitted by the planet
  • Goldilocks zone is Earth's location where the temperature is just right
• Water


  • Most important ingredient in biological processes
  • Absence of water will interfere with reactions necessary for life
  • Solid form (ice) hinders living organisms to use it
  • Solid (ice) in the 2 poles and liquid along the equator (can be consumed)
• Atmosphere


  • Provides chemicals needed for life: carbon dioxide, nitrogen
  • Provides insulation/shielding from the sun and impact of small to medium size meteorites
  • Greenhouse gases like carbon dioxide (CO2) and methane (CH4) trap heat and avoid our planet from freezing
  • Ozone (O3) layer shields the Earth's surface from harmful UV radiation
  • Size and distance from the sun affects the ability of the Earth to hold a significant amount of atmosphere
  • Presence of gravity also sustains the atmosphere
• Energy


  • Earth has rich sunlight to support life
  • Living organisms like plants and photosynthetic bacteria use light as a source of energy
  • Chemosynthetic organisms rely on chemical energy to support biological processes
  • Earth's position from the sun is just right to enable it to harness enough amount of sunlight
• Nutrients


  • Essential factor used to build and maintain organism's body structure
  • Insufficient amount can impede synthesis of biological molecules
  • Volcanism helps in cycling nutrients
  • Water, carbon, and oxygen are some examples of nutrients
• Spheres of the Earth

  • Atmosphere
  • Geosphere
  • Hydrosphere
  • Biosphere
• Crust


  • The outermost layer and is composed of solid rock
  • Divided into continental crust, which is thicker and makes up the continents, and oceanic crust, which is thinner and covers the ocean basins
• Mantle


  • The layer beneath the crust and makes up the majority of the Earth's volume
  • Composed of solid, but flowing, rock called mantle rock
  • The uppermost part of the mantle is partially molten and is known as the asthenosphere
• Inner Core


  • The innermost layer of the Earth and is solid due to the extreme pressure
  • Primarily composed of iron and nickel and is the hottest part of the Earth
• Outer Core


  • A liquid layer made up mostly of iron and nickel
  • Surrounds the inner core and is responsible for generating Earth's magnetic field
• Asthenosphere


  • The layer that lies after the lithosphere (100-250km) beneath the Earth's surface
  • The balance between temperature and pressure is such that the rocks have little strength (weak) and easily deformed
  • Plays a critical role in the movement of plates on the surface of the Earth according to plate tectonic theory
• Lower Mantle


  • Hot and exhibits "Plasticity"
  • In between the upper mantle and outer core of the earth
  • Gutenberg discontinuity is detected between Earth's lower mantle and the outer core as observed by changes in the seismic waves
  • Thickness: 2,240 km
• Oceanic Crust


  • Dark shaped color
  • Rock Sample: basalt
  • More dense
  • Thin layer, 50 km
• Continental Crust


  • Light-Colored
  • Rock Sample: Granite
  • Less Dense
  • Coarse-Textured
  • Thick Layer, 40-70 km
• The Earth's molten metallic core gave rise to magnetic field. The magnetic field is attributed to dynamo effect of circulating current. The nature of the dynamo are not known in detail, however, it is always linked to the rotation of the earth.
• Layers of the Atmosphere

  • Stratosphere
  • Troposphere
• The biosphere contains the entirety of Earth's living things. It is sometimes referred to as the "zone of life." The biosphere is divided into biomes namely aquatic, forest, desert, and tundra.
• Lithosphere


  • The solid outer section of Earth
  • Includes the entire Earth's crust and the rigid upper mantle
  • Where we can find the lithospheric plates also called the tectonic plates
  • The two plates are the continental and oceanic plate
• Hydrosphere


  • The combined mass of water found on, under, and above the surface of a planet, minor planet, or natural satellite
  • Oceans are then divided into layers known as zones namely horizontal zones (coastal zone and pelagic zone) and vertical zone (epipelagic zone, mesopelagic zone, bathypelagic zone, abyssopelagic zone, and hadalpelagic)
• Alfred Wegener proposed the "Continental Drift" theory, which is the foundation of plate tectonics
• Earth's subsystems


  • Lithosphere
  • Hydrosphere
  • Biosphere
• Lithosphere


  The solid outer section of Earth, including the entire Earth's crust and the rigid upper mantle, where the lithospheric/tectonic plates are found
• Hydrosphere


  The combined mass of water found on, under, and above the surface of a planet, minor planet, or natural satellite, divided into horizontal and vertical zones
• Silicon makes up 15 percent of the Earth's crust
• Tectonic plate theory


  The Earth's outer shell (lithosphere) is divided into several plates that glide over the Earth's rocky inner layer (mantle)
• Tectonic plates


  • Act like a hard and rigid shell compared to the Earth's mobile mantle
• Alfred Wegener


  The father of plate tectonics, proposed the "Continental Drift" theory in 1912 which was initially ridiculed
• Plate tectonic driving forces

  • Mantle convection currents
  • Ridge push
  • Slab pull