<span>An eon is a geologically around tens of millions of years. A period is a million year included in an eon which is also made up of several eras. Therefore my answer is a period due to it being a subset of an era which is a subset of an eon.</span>
Answer:
Delta
Explanation:
Delta is a geographical term that describes the formation of wetlands. It is formed from the slow movement of water and deposit from a river into a larger water body. For example lake, sea and ocean. A vivid example is a place where the River Nile moves at a slower pace into the Mediterranean Sea.
Hence, in this case, as a river reaches its mouth it is often affected by incoming tides resulting in a formation called a DELTA.