Answer:
Glaciers carved out the fjords. Glaciers protected nearly everything during the last ice age on Earth.
Estuaries in the River Valley have been drowned. Coastal plain estuaries include the Chesapeake Bay on the East Coast and the Coos Estuary on the West Coast.
Estuaries built with a bar.
Tectonic Estuaries are a form of tectonic estuary.
Fjords are a type of fjord.
