Earth -Plate Tectonics Flashcards
Who was continental drift proposed by?
Independently by Alfred Wegener and Frank Taylor
What was continental drift originally based on?
Rare fossils, American-European-African contnents and mountain belts fitting together.
What is the flow of mantle convective currents?
Upward moving arms reach the lithosphere, move along it, cooling as they go, eventually sinking back to the interior
Paleomagnetism
This studies ancient mole positions, using remanant magnetization to reconstructs direction and strength of geomagnetic field in the past.
How do underwater volcanoes form?
Upward currents penetrate the lithosphere
What is the basis of paleomagnetism?
Iron oxide in igneous rocks which is highly magnetic
Curie point
This is the temperature a material loses its ferroelectric and piezoelectric behaviour
Ferroelectric
Materials exhibiting spontaneous electrical polarisations, switchable by external electric fields.
Piezoelectric
Materials developing electric charges in response to applied mechanical stress respectively.
How does paleomagnetism infer past magnetic fields?
Magnetite in erupted lava, cooled to the curie point, are fixed to their orientation towards Earths magnetic field.
Earth magnetic field fluctiation
It reverses every 70 million years, a north-point compass would point south bound 70 million years ago
Divergent Plate Boundaries
Effusive basaltic volcanism where new crusts are formed
Convergent Plate Boundaries
This is where lithosphere is overriden bty another, pushed into the asthenosphere in subduction
Example of Divergent and Convergent structures
San Andreas fault and Alps and Himalayas respsectively
What causes tectonic plate movement?
Convection cells, where deep heat is brought from core to the Earth surface
