Tide-Dominated Deltas

These tidal sand ridges are characteristic of the subaqueousdelta plain. They may reach relief heights of up to 15-20 meters close to the shoreline. Relief of the ridges decrease with increasing distances from the distributaries. Ridges are also greater in relief and size when there is more tidal discharge than fluvial discharge. Sediments that make up the sand ridges are fine to medium sands. Characteristic of the lower delta plain are broad tidal flats that grade unidirectionallyinto the sand bars and the opposite direction into marshes or evaporative flats (depending on climate).
The delta has a gradational, upward coarsening sequence of muds; interbeddedsands, silts, and muds; and then fine to medium sands. Due to the eroding effect of tides, the sands display cross-bedding, the sand ridge field can be truncated through erosion, and the distributarychannel sediments contain more slack-water mud drapes than usual.