Plate tectonics

• Convection currents in the mantle drive the movement of tectonic plates.
• The mantle is made of solid rock.
• The three main types of plate boundaries are convergent boundaries, divergent boundaries, and transform boundaries.
• The features of a divergent plate boundary include mid-ocean ridges, rift valleys, and volcanic activity.
• The features of a convergent plate boundary include subduction zones, volcanic arcs, and mountain ranges.
• Transform plate boundaries are characterized by the horizontal sliding of two lithospheric plates past each other, resulting in earthquakes and the absence of volcanic activity.
• Characteristics of a convergent plate boundary include the collision or subduction of tectonic plates, the formation of mountains or trenches, and the potential for volcanic activity and earthquakes.
• At a transform plate boundary, two tectonic plates slide past each other horizontally, causing earthquakes.
• At a convergent plate boundary, two tectonic plates collide and can either form mountains or cause one plate to be subducted beneath the other.
• At a divergent plate boundary, two tectonic plates move away from each other, creating a gap where magma rises to form new crust.
• Subduction in plate tectonics is the process where one lithospheric plate sinks beneath another into the Earth's mantle.
• The two types of crust on Earth are continental and oceanic.
• The three main layers of the Earth are the crust, mantle, and core.
• Some evidence for continental drift are:

  continental fit

  similarity of rocks and mountain ranges

  fossil evidence
• Alfred Wegener proposed the Continental Drift hypothesis in 1912.
• The pangea consists of:

  Laurasia (Northern land mass)

  Gondwana (Southern land mass)
• Features of the seafloor includes:

  • Continental margin
  • Abyssal plain
  • mid-oceanic ridges
  • Ocean trenches
• Convection: the hot fluid goes up, cold fluid goes down.
• Paleomagnetism is the remnant magnetism in ancient rocks.
• Seafloor spreading was proposed by Harry Hess in 1962.
• Seafloor spreading theory suggested that seafloor separates at oceanic ridges and provided the “how” to Wegener’s hypothesis.
• Oceanic crust at the spreading ridges are younger than oceanic crusts farther from ridges.
• Unifying Theory

  • Patterns of the continents
  • Patterns of seafloor ages
  • Patterns of seafloor depth
  • Patterns of magnetism
  • Patterns of volcanoes
  • Patterns of earthquakes
• Examples of convergent (oceanic-oceanic) boundaries can be seen in Japan and the Philippines.
• An example of oceanic-continental convergent is the Andes.
• An example of continental-continental is the Eurasia-India plate/Himalayan mountains.
• What moves the plates?

  Convective heat system and gravity-driven plate motion
• What are some sources of heat?

  Radioactive decay, accretion, and differentation
• What is ”slab-pull”?

  Pulling the plate behind a subduction cold slab of lithosphere
• What is “ridge-push”?

  Gravity pushes oceanic lithosphere away from higher spreading sites and towards subduction.