Estuary

Overview

A sedimentary system composed of a series of sedimentary facies in estuary at the river mouths. Estuary is a variety of bays which is at the tide-dominated river mouths. Estuary is a shape of bays intruded into the land and is usually formed in the transgressive process, whereas delta is a shape of land protruded into the sea and is usually formed in the regressive process. Sediments deposit on the seafloor of the bay. It is considered as a system during the transitional stage from the low sea level to high sea level, and during the high sea level stage for large rivers.

Composed of tidal river sediments (upward-fining sands), tidal flat sediments (finely interbedded sands and mud), sand bar sediments (packed shellfish fossils), transgressive sands (poorly sorted sands), tide-influenced shallow marine deposits (upward-fining sands and mud including finely interbedded sands and mud), estuary-mouth shoal sediments (upward-fining sands and mud).