Earth photos

Stromatolites The ages of the Earth

Stromatolites The ages of the Earth

The photo shows a stromatolite community on the western Australian coast. These primitive organisms are the oldest known way of life. Looking back, we all owe them our existence.

The oldest stromatolite fossils are between 3,700 and 3,900 million years old. They hold the record of survival on Earth, because even today they can be found in shallow areas of warm waters, such as the western coast of Australia, the Bahamas, the Red Sea, and some areas of South America.

Stromatolites, also called stone beds because of their rocky appearance, are actually layers of underwater bacteria that cluster on sedimentary rocks. His great contribution to the evolution of life was photosynthesis.

The microorganisms that form stromatolites are a type of cyanobacteria, that is, bacteria capable of taking their energy from sunlight. Through photosynthesis, a large amount of oxygen began to be released. Over millions of years, oxygen accumulated in the oceans. When mixed with the abundant iron in the water, it produced rust, and settled on the seabed. This gave rise to large iron deposits that we still exploit today.

The production of oxygen as a waste of photosynthesis continued to increase and, finally, also filled the atmosphere. In this way, stromatolites opened the way to new life forms, capable of breathing oxygen from the air.

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