River delta slope offshore, waves will make river deltas smoother. Waves can also be responsible for carrying sediments away from the river delta, causing the delta to retreat. For deltas that form further upriver in an estuary, there are complex yet quantifiable linkages between winds, tides, river discharge, and delta water levels. Erosion is also an important control in tide-dominated deltas, such as the Ganges Delta, which may be mainly submarine, with prominent sandbars and ridges. This tends to produce a "dendritic" structure. Tidal deltas behave differently from a river- and wave-dominated deltas, which tend to have a few main distributaries. Once
Mississippi River Delta the Mississippi embayment. The embayment began focusing sediment into the Gulf of Mexico, which facilitated the deltaic land-building processes for the future. During the Paleogene Period (approx. 65.5 to 23 million years ago), a series of smaller scale, regional rivers entered present-day southern Louisiana allowing an increase in dispersion of sediment deposition into the delta region. The Mississippi embayment then became a primary focus of sediment deposition during the Miocene Epoch (approx. 23 to 5.3 million years ago), which built the foundation of the modern delta region. The modern day Mississippi River Delta plain began to evolve during the Holocene