1. 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)

2. Arcuate
• Nile Delta,
Egypt
• Rounded,
convex
margin

3. Cuspate
• Apalachicola River
Delta, Florida, USA
• Tiber, Italy
• Material spread
evenly either side
of estuary
• ‘Tooth’ shaped

4. Bird’s Foot
• Mississippi Delta,
Louisiana, USA
• Many sediment-
bounded channels
extending out in a
fan shape.