The Mississippi River has built a series of deltas over time, resulting in overlapping lobes of deltaic sediment. The current delta, the Balize, or "Bird Foot," is approximately 1,000 years old. This delta is southeast of New Orleans, but the river is slowly shifting its course to the Atchafalaya distributory. This long-term process of river mouth shifting has taken place repeatedly in the Holocene period.
Most of the greater Mississippi River delta consists of marshland and mud flats with numerous shallow lakes and intertwining channels. The marsh features aquatic plants and an extensive amount of waterfowl. The large amount of sediment from the river has influenced the growth of barriers islands and cheniers. Mangrove coasts and marshes are also common in this area.