Stromatolites are layered rock formations that are mainly formed in shallow layers of salt or fresh water. They are formed as a result of the biological activity of cyanobacteria, which are otherwise called blue-green algae. Cyanobacteria uses water, carbon dioxide, and sunlight to make their food, then emit oxygen as a supplement.
During the Proterozoic period (about 2.5 billion years ago to 540 million years ago), the rocks composed of stromatolites were enormous, some reaching up to several hundred meters. Individual deep underwater stromatolites reached up to 75 meters in height. Proterozoic stromatolites had a rather complex microstructure, while those formed by microbes from the time period are simpler.
The most common stromatolites consist mainly of calcium carbonate, since carbonate-type sediment is more common in the seas. Nevertheless, phosphate, iron, earth and other types of stromatolites are also formed under other hydrochemical conditions. The coloration of the multilayer can change during the day, because the inhabitants of the lower layer can climb up during the dark and vice versa. Microbes slide up and down at a speed of 2 centimeters per hour.
The outer layer of stromatolites is up to 2 cm. thick multi-layered “carpet”, at the base of which are benthic or palmelloid cyanobacteria, while other types of bacteria also exist.
The lower layers can be easily separated:
- A dense upper layer (1 – 1.5 mm), where there are both oxygen-producing (so-called “photosynthesizing cyanobacterial”) organisms and microbes that cannot live without oxygen.
- A thin (narrower than 1 mm) “wallpaper” in which microbes synthesize organic substances from inorganic substances, performing photosynthesis, in which the source of oxygen is not water, but another substance, such as hydrogen sulfide, in which it is separated is not molecular oxygen, but sulfur.
- Upper 2 layers, where photosynthesis takes place, comes a thick, oxygen-deprived zone where bacteria live that do not need molecular oxygen. Often they are poison.
Stromatolites are considered to be the oldest known form of life.
They actually appear in the records of the oldest geologic weathered formations in South (Western Australia) dating back up to 3.5 billion years.
With great probability, it is assumed that there are stromatolites at the bottom of Lake Sevan, which foreign scientists are interested in. ArmDiving has conducted and continues to conduct numerous research dives in the suspected and adjacent areas to provide required material to scientists for further research.
