The steeper the dip the closer the island arc is to the trench - can you see why? The change can be explained by allowing the India subcontinent to drift from left to right south to north relative to a steady magnetic field that dips to either side of the equator.
The movement of newly generated oceanic crust away from spreading centers was proposed to be driven by thermal convection cells. Averaged over a short period tens of thousands of yearsthe magnetic pole coincides with the geographic pole, as indicated by the red and blue spots.
When geologists began to collect paleomagnetic data from the ocean crust in the 's, they observed that recent polar wandering was confined within the high Arctic and Antarctic. Ocean - Continent : subduction of sea floor with development of a volcanic arc like the Andes.
Click Here to return to the search form. Basaltic melts can invade these fractures and eventually a new ocean may form. The continents collide, move together for a while and then split up again, much as North America and Eurasia did in the Paleozoic.
Choose Apparent Polar Wandering in this animation. For example, dinosaur fossils found in South America and Africa provide evidence that the two continents used to be part of the same larger land mass, Gondwanaland: click here please The theory of continental drift famously argued by Alfred Wegener in did not become widely accepted until we could explain why and how the continents moved.