[Q4] SCI

• The science that deals with understanding earth’s structure is called geology
• Earth's interior is characterizedby a gradual increase intemperature & pressure as itgets deeper
• Crust


  The thinnest and the outermost layer of the Earth
• Oceanic Crust


  • Rocks of the oceanic crust as Sima which stands for silicate and magnesium, the most abundant minerals in oceanic crust
  • It makes up the seafloor. It's thinner, denser, and simpler in structure than the continental crust
  • It composed of dark, igneous rock called basalt
• Continental Crust


  • Also called as Sial because its bulk composition is richer in aluminium silicates (Al-Si) and has a lower density compared to the oceanic crust
  • It is composed of granitic rocks, which have even more silicon and aluminum than the basaltic oceanic crust and are less dense than basalt
• Subduction


  When an oceanic plate converges with a continental plate, the oceanic crust will always subduct under the continental crust; because oceanic crust is naturally denser
• Mantle


  The mostly solid bulk of Earth's interior. The mantle lies between Earth's dense, super-heated core and its thin outer layer, the crust
• Upper Mantle


  • It is mostly solid, but it's more malleable regions contribute to tectonic activity
  • Two parts are the lithosphere and the asthenosphere
  • The lithosphere includes both the crust and the brittle upper portion of the mantle. The lithosphere is both the coolest and the most rigid of Earth's layers
  • The asthenosphere is the denser, weaker layer beneath the lithospheric mantle
• Lower Mantle


  • The lower mantle is hotter and denser than the upper mantle and transition zone
  • The lower mantle is much less ductile than the upper mantle and transition zone
• Mantle convection


  Transfers heat from the white-hot core to the brittle lithosphere. The mantle is heated from below, cooled from above, and its overall temperature decreases over long periods of time
• Core


  The very hot, very dense center of our planet. The ball-shaped core lies beneath the cool, brittle crust and the mostly solid mantle
• Outer Core


  • It is mostly composed of liquid iron and nickel
  • The liquid metal of the outer core has very low viscosity, meaning it is easily deformed and malleable. It is the site of violent convection. The churning metal of the outer core creates and sustains Earth's magnetic field
• Inner Core


  • It is a hot, dense ball of (mostly) iron
  • Its intense pressure—the entire rest of the planet and its atmosphere—prevents the iron from melting
  • Some geophysicists prefer to interpret the inner core not as a solid, but as a plasma behaving as a solid
  • It rotates a little differently than the rest of the planet. It rotates eastward, like the surface, but it's a little faster
• Lithosphere


  Sphere of rock. It includes the crust and uppermost mantle, 100 - 250 km thick
• Asthenosphere


  Lies beneath the lithosphere in the upper mantle, soft, comparatively weak layer
• Mesosphere


  Lies between 660 and 2900 km. It is more rigid layer
• Continental Drift Theory


  • Earth's continents are came from a single large landmass
  • "Pangaea" means supercontinent or large landmass. It is also translated as "all Earth"
  • Proposed by Alfred Wegener
  • Panthalassa: a large and vast bodies of water that surrounds the supercontinent
  • As the supercontinent drift, it forms two great landmasses called "Eurasia" and "Gondwana"
• Plates


  • Primary Plates - Pacific, North America, Eurasia, Africa, Indo-Australian, Antarctica, and South America
  • Secondary Plates - Caribbean, Cocos, Juan de Fuca, Nazca, Philippines Sea, Scotia
  • Tertiary Plates - microplates – very small in size and global presence
• Asthenosphere


  Solid upper mantle material that is so hot that it behaves plastically and can flow. Plays an important role in plate tectonics
• Lithosphere


  The outermost mechanical layer. Behaves as a brittle and rigid solid. Rides on the asthenosphere
• Plate boundaries


  • Divergent (moving apart) - also known as constructive boundaries, often forms a mountain chain known as a ridge, forms as magma escapes into the space between the spreading tectonic plates, involves the process of spreading
  • Convergent (moving together) - also known as destructive boundaries. happens when one tectonic plate dives underneath the other. involves the process of subduction
  • Transform (moving side by side) - occurs when two plates slide past each other, it forms transform fault, involves the process of lateral sliding