Another important driving force is ridge push This gravity-driven mechanism results from the elevated position of the oceanic ridge, which causes slabs of lithosphere to "slide" down the flanks of the ridge. Ridge push appears to contribute far less to plate motion than slab pull. The primary evidence for this comes from comparing rates of seafloor spreading along ridge segments having different elevations. For example, despite its greater average height above the seafloor, spreading rates along the Mid-Atlantic Ridge are considerably less than spreading rates along the less steep East Pacific Rise. In addition, fast-moving plates are being subducted along a larger percentage of their margins than slow-moving plates. this face supports the notion that slab pull is a more significant driving force than ridge push. Examples of fast-moving plates that have extensive subduction zones along their margins include the Pacific, Nazca, and Cocos plates.