Ocean Basins

• Ocean basins are vast submarine regions that collectively cover nearly three-quarters of Earth’s surface
• Continents stand high about 1km because they are light and thick
• Oceanic crust- dense, thin

  Continental crust- light, thick
• The crests of oceanic ridges are spreading centers where two plates move apart from each other at a rate of several centimeters per year
• • Molten rock material wells up and solidifies into oceanic crust, creating new ocean floor.
  • At the deep-sea trenches, two plates converge where it is melted
  • Thus, for each segment of new ocean floor created at the ridges, an equal amount of old oceanic crust is destroyed at the trenches
• Latest phase of ocean basin growth is 200 million years ago, Pangea supercontinent
• Folds are formed when tectonic processes put stress on a rock, causing it to bend instead of breaking. Ex: Appalachian Mountains
• Faults occur when tectonic plates slide horizontally past each other, creating giant fractures in Earth’s crust
• Trenches are long, narrow depressions on the seafloor, formed as a result of tectonic activity
• Volcanoes: Most volcanoes form at the boundaries of Earth’s tectonic plates Produce by divergent plate boundaries and convergent plate boundaries
• Rift valleys form when tectonic plates beneath the Earth’s surface diverge
• Mountain ranges form where two continental plates collide