The Formation Process
The formation of Stromatolites begins with cyanobacteria. These single celled bacteria live in mats on the seafloor which secrete mucilage (mucus) over them. From this point there are 2 ways in which the process continues:
Trapping/Binding
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Calcite Precipitation
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Marine stromatolites tend to form through the "Trapping/Binding" method, and non marine stromatolites found in places like lakes tend to form using the "Calcite Precipitation" method. In either case:
- The cyanobacteria are prevented from performing photosynthesis
- They penetrate through the material and colonize the surface to form a new algal layer on top (either binding sediment or growing through the calcite in the process)
- Over time this process accumulates layers which cause the stromatolite to grow in size
The result is a layered structure in which the bacteria sit on top repeating the accretionary process over and over again.