Plate tectonics

A sketch of the effect of mantle convection on the crust:

1. rising and diverging mantle convection currents push plates apart, allowing magma to feed the mid-ocean ridge
2. sinking and converging mantle convection currents pull plates together, causing subduction
3. rising and diverging mantle convection currents split the continentalcrust, creating a rift valley
4. subducted slab melts, feeding magma to the island arc volcano above
5. magma created by subduction forms volcanoes and granite masses in the overlying plate

Reference

Southampton Oceanography Centre, Challenger Division for Seafloor Processes (2004) Classroom@Sea Project. http://www.soc.soton.ac.uk/CHD/classroom@sea/carlsberg/images/plate_history_lge.jpg (accessed 22 August 2004). Image based on artwork from the US Geological Survey.

home