<span>True, however 50% is rather optimistic value, it's probobally more. The main source of water is in the ground and the groundwater gets constantly more contaminated with road salt, oil, gasoline and other chemicals (and as you can see, these are all manmade products).</span>
agriculture is the answer
At convergent plate boundaries, sedimentary rock from the ocean floor gets pushed down into the mantle. The crust increases in temperature as it dives deeper into the mantle. Eventually, the crust melts and rises to the surface causing a volcanic eruption, creating igneous rocks.
