PLATE TECTONICS

"First there is a mountain, then there is no mountain, then there is." - Donavan

The single most important idea in geology is the theory of plate tectonics. This is the scientific theory that explains how many of Earth's geologic processes work to form mountains, ocean trenches, volcanoes, cause earthquakes, and act to recycle rocks

and minerals.

Plate Tectonics is an explanation supported by definitive scientific evidence; here's

what it says:

Earth's crust is not one continuous, unbroken rocky shell. Instead it is a rocky shell that is broken up into about one dozen enormous slabs called tectonic plates. The plates literally float on a mantle of molten rock (magma). Slow moving current flows of magma are strong enough to move the plates and as they do, they interact at the boundaries in three different ways:

1) Plates converge, or collide into each other. The convergence of continental plates

produces mountain ranges like the Andes, the Alps, and the Himalayas. When an oceanic

plate converges with a continental plate it subducts (dives under), forming mountains and

areas of volcanic activity. Converging plates also send rocks and minerals back down into

the mantle where they are melted and eventually returned to surface in a process known

as the rock cycle.

2) Plates diverge, or pull apart. Diverging continental plates produce rift valleys; diverging oceanic plates produce ocean trenches and underwater mountain chains.

3) Plates slide or rub against each other at transverse boundaries. Sometimes these sliding

plates get stuck - until they suddenly slip; the result is an earthquake!