GROUNDWATER is the largest source of freshwater on earth.
Ocean currents act much like a conveyor belts, transporting warm water and precipitation from the equator toward the poles and cold water from the poles back to the tropics. Thus, currents regulate global climate, helping to counteract the uneven distribution of solar radiation reaching Earth's surface.
Mass extinctions occur for many reasons. Changes in the environment might make it impossible for the local life to survive, diesease or drought might strike, or there might be a natural disaster. These extinctions make good divisions in geologic time because they are easy to locate over a wide area and mark a definitive change in the Earth's systems.
Its called till just look it up
