Tectonics Flashcards
Thickest layer of the earth?
The Mantle, it can reach 1000°C when near the crust and 5000°C when near the core. Made up of solid rock that can flow- plastic rock.
Thinnest and coldest layer of the earth?
The crust, made up of solid rock that’s broken up into pieces called tectonics. Contains rocks and minerals
What is the outer core?
The outer core is beneath the mantle, it is 2200km thick and is 5300°C. It is made up of semi liquid iron.
What is the inner core?
The inner core is 1200 km thick. It is over 5500°C. It is mainly made up of iron and nickel. The rock is solid in the inner core due to the pressure.
What was Wegener’s theory?
Wegener’s theory was that all the continents used to be together, split apart over millions of years due to the plates moving. He called the idea “Continental Drift”.
What are convection currents?
Convection currents occur when heat in the mantle rises and sinks causing the tectonic plates to move.
How do convection currents work?
The magma is heated to 5000°C in the mantle and rises to the crust where they cool and sink only to be heated again. Convection currents are when the heat is pushed up in the mantle and pushed back down, this becomes a cycle.
How is a volcano formed?
Magma rises through cracks or openings in the crust. Pressure builds up inside the earth, when the pressure releases magma explodes to the surface causing a volcanic eruption. The lava from the eruption cools to form new crust. Over time, the rock builds up and a volcano forms.
What are the types of plate boundaries?
- Divergent: plates move apart
- Convergent: plates move toward each other
- Transform: plates slide past each other
- Collision zones: form when two continental plates collide
What is the difference between continental and oceanic plates?
Continental plates are much thicker than Oceanic plates.
What happens at divergent plate?
The plates move apart. Volcanoes are formed as magma wells up to fill the gap, and eventually new crust is formed. An example of a divergent plate boundary is the mid-Atlantic Ridge.
What happens at a transform plate?
Earthquakes occur at transform plate boundaries. The plates get stuck while sliding past each other and there is a build up of pressure. When the plates finally slip past, the pressure is released and causes an earthquake. An example of a transform boundary is the San Andreas Fault.
What happens at a convergent plate?
The oceanic plate is forced under the lighter continental plate. An example of a destructive plate boundary is where the Nazca plate is forced under the South American Plate.
What happens at a collision zone?
Collision zones form when two continental plates collide. Neither plate is forced under the other, and so both are forced up and form fold mountains.
What is the focus in an earthquake?
The point in the crust where the earthquake happens.
