In Louisiana, and in many places, the term "delta" is widely used. That's mainly because we live on a delta - the Mississippi River Delta - and much of the land that comprises coastal Louisiana was built by the Mississippi and other rivers creating new deltas over millennia. From a more technical standpoint, identifying what a delta is and its various components may not be as easy for most people. Many people picture a delta as a place where a river meets open water, and land protrudes outward as sediment accumulates near the mouth. What some may not know is that there is more to a delta than what we see in satellite images. Some of the most important parts of a delta are below the surface.