Part one of term paper
When examining waters transition from fresh to salt as well as from salt to fresh one quickly finds the importance of estuaries. In terms of geology, present-day estuaries are young and ephemeral coastal features. Today's estuaries began to take their current form during the last interglacial period, when sea level rose about 120 m (Braun 3 ...

Part two of term paper
... sea level rises, estuaries tend to fill with sediments and become much smaller. The sediments come from riverborne terrestrial materials from the eroding continents and from sand transported upstream by the tides from the continental shelf (Braun 55). It is in estuaries that most of the world's freshwater runoff encounters the oceans. Because fresh water is lighter, or less dense, than salt water, unless the two are mixed by the tides or winds, the fresh water remains at the surface, resulting in a ...