Related Clues:
- Triangular letters
- Some fertile regions
- River formations
- River features
- Triangular deposits
- River plains named for their usual shape
- Coastal waters
- Rivers' mouths
- Greek D's
- Nile and Mississippi
- River mouth formations
- Pointed river formations
- River areas named for their shape
- The Mekong and Nile have them
- River mouth features