Delta Formation • Areas of sediment deposited at the mouth of river • Fast moving water enters a slowing moving body such as sea or lake • Discharge, and therefore competence, reduces dramatically - resulting in deposition of even very fine material • Flocculation occurs when salt water meets fresh water – clays stick together and sink to floor • Highly changeable landforms as sediment is unconsolidated – erosion and incursion by the sea too • Deposition rate must be greater than erosional rate So – 2 major conditions: • Form on rivers with high sediment rate (Mississippi – 450m tonnes a year) • Rivers flow into bodies of water with little wave action (Nile into the Mediterranean)