deltaa triangular area of land formed at the mouth of a river by deposited sedimentRiver deltas are among the most fertile and densely populated regions in the world.NoteRiver deltas are among the most fertile and densely populated regions in the world.Elon.io is an online learning platformWe have an entire course teaching IELTS Vocabulary — Band 7+ grammar and vocabulary.Start learning IELTS Vocabulary — Band 7+ now