Question

what is a delta how they are formed

Answer 1

When a river reaches a lake or the sea the water slows down and loses the power to carry sediment . The sediment is dropped at the mouth of the river. Some rivers drop so much sediment that waves and tides can'tcarry it all away. It builds up in layers forming a delta.

Answer 2

Hi !

Deltas is a part land which is made by rivers. Rivers carry silt and sediments from Mountains and deposit in plains to form deltas.