40 points please hurry marine biology. South Carolina has a small river that flows into the sea. Over time, sediments build up along the coastline and cause the body of water to be cut off from the sea. What type of estuary undergoes this kind of change?

(*blank*) estuaries can get blocked off from the sea due to deposition of sediments.

Types of Estuaries

There are four different kinds of estuaries, each created a different way:  coastal plain estuaries  tectonic estuaries;  bar-built estuaries; and  fjord estuaries.

Coastal plain estuaries are created when sea levels rise and fill in an existing river valley. The Chesapeake Bay, on the East Coast of the United States, is a coastal plain estuary.

Chesapeake Bay was formed at the end of the last ice age. Massive glaciers retreated, leaving a carved-out landscape behind. The Atlantic Ocean rushed to fill in the wide coastal plain around the Susquehanna River, creating a large estuary known as a ria: a drowned river mouth.

Tectonic activity, the shifting together and rifting apart of the Earth's crust, creates tectonic estuaries . California's San Francisco Bay is a tectonic estuary.