Atriangular shaped body of water that forms where a stream in to the larger body of water is a

This triangular body of water is called a delta. It is shaped like the Greek letter delta and was coined by Herodotus, the father of history who lived from 484 to 425 BC by seeing the deltoid shape at the mouth of the Nile.

Deltas occur throughout the world except at the poles. They all have three things in common, namely:

1. The presence of a large catchment basin. The top 30 river deltas all have catchment basins.

2. They all are at the mouth of large river systems that carry large quantities of clastic sediments (soils or portions of rocks that have been moved by water from where they formed)

3. They are not found near geologically active coastlines. They take a long time to develop so they are very rarely situated on tectonically active coast.

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