Biogenic · Cross section
Stromatolites
Layered, often domal sedimentary structures built by microbial mats.
- How it forms
- Photosynthetic microbes such as cyanobacteria trap and bind sediment in stacked sheets, growing upward toward light.
- Typical setting
- Shallow water; modern examples mainly in hypersaline lakes and marine lagoons, such as Shark Bay, Western Australia
- Way up
- Not a way-up indicator
- Flow direction
- No.
Photo examples
Filter all structures Practice identifying them