Delta formation

A delta is a landform, it is an area that looks like the Greek letter "delta"   (look at the picture), also it looks like a triangle. This area forms at the rivers' mouth, just where they meet the ocean. Erosion and deposition play an important role in "deltas" formation. Erosion moves the weathered materials (pieces of rock, sand, sediments, etc.) along the river, as it flows to the ocean. All these materials are deposited at the river's mouth forming this triangle or "delta". If you look at a delta from a plane, it will look similar to the roots of a plant. Here are some pictures which will give you an idea of what a delta is:

Here are a couple of videos which show how the Nile River's delta in Egypt and the Mississipi River's delta in The United States formed and how they look. Watch them, I think you will get a better idea about what a "delta" is:

http://www.youtube.com/watch?v=gmjjxxu7tWc

http://www.youtube.com/watch?v=t_IIA2o6-lk