Oceans cover about 70 percent of the surface so of the Earth and the water in the oceans is about 3.5 percent salt. That's a lot of salt. In fact, if the oceans dried up completely, there would be enough salt left behind to build a 180-mile-tall, one-mile-thick wall around the equator! Salt is a mineral that is found in soil and rocks. But how does salt get from rocks and soil into the oceans? It's all part of a cycle of related events that happen again and again in the same order. As rain falls, water flows over the land and through rivers. On its way, it picks up small amounts of mineral salts from the rocks and soil of the riverbeds. Rivers then carry the salty water to the ocean. Scientists estimate that about four billion tons of salt are one s carried to the oceans annually. What happens next? The heat from the sun causes some of the ocean water to evaporate(go from a liquid to 3 a gas), but the salt is left behind in the ocean