Plate Tectonics Flashcards
What are earths 4 major layers?
- Lithosphere (crust)
- Mantle
- Outer core
- Inner core
How have the layers been studied?
We only know about the crust from direct observations. The core is too hot and deep to be studied directly, so geologists have determined their composition by indirect observations.
How thick is the lithosphere?
35km to 100km thick, depending on the location.
What three major rocks make up the lithosphere?
Sedimentary, igneous, metamorphic
What is the moho?
• The bottom boundary of the lithosphere is the Mohorovicic discontinuity (or Moho), named after Adrija Mohorovicic, the Croatian
scientist that discovered it.
• The Moho marks the boundary between the crust and the molten
mantle beneath.
Due to the increased pressure and temperature in the mantle, the rock
in this layer acts like a fluid, called…
Plastic rock
(Plasticity is the ability for a substance to be easily shaped or molded.)
What happens as the molten rock in the mantle heats and cools?
It is very likely that this molten rock is moving in convection currents
What is the outer core made of?
Liquid iron
What is the inner core made of?
Solid iron
(The inner core is even hotter than the outer core, but due to the immense pressure, the atoms are compacted into a solid.)
What are tectonic plates?
Tectonic plates are solid pieces of lithospheric rock that move on the upper portion of the mantle,
called the asthenosphere.
How do tectonic plates move?
• Convection currents that are warming or cooling carry plates towards or away from each other.
• Denser oceanic plates subduct, pulling the rest of the plate behind it.
• Suction also pulls the subducting plate into the mantle.
What is the continental drift?
the theory that all of the continents were once joined together in a single landmass and have since drifted apart
What is evidence of the continental drift theory?
Similarities in the shape of Africa’s west coast and South America’s east coast as well as similarities in fossils
(Fossil remains of the Mesosaurus were found in South America and South Africa)
