We explain what the Archaic Aeon was, the stages into which it is divided, and its characteristics. Also, the first forms of life and the oceans.
In some classifications it is treated as the first, including in the Archaic the events of the Hadic or Azoic Aeon . This is because the difficulties of studying these ancient times do not allow us to determine with certainty when one ends and the other begins.
It is presumed that the Archaic began approximately 4,000 million years ago , once the Earth was formed, in its most primitive geological and atmospheric stages. It ended about 2.5 billion years ago, beginning the Proterozoic Aeon.
The Archaic was a significant period in the early formation of the planet, in which primitive life emerged and the first evolution of the earth's crust occurred . Its name comes from the Greek arche , "origin" or "beginning."
Their names suggest the absence of life since it is the period of stabilization and initial cooling of the Earth.
Atmospheric and chemical conditions were incompatible with life. It is the initial eon of the Precambrian and of the geological history of the world.
The latter is due to the fact that the heat flux of the planet towards its crust was three times greater than the current one , which increased the movements of the lithosphere and allowed much smaller plates as well.
Thus, there were no large continents on the planet until the end of the Archaic , but protocontinents that collided constantly and on at least three occasions met to temporarily form a larger unit.
Towards the end of the period, it is possible that volcanic and tectonic activity destroyed more than one continent . Among the rocks generated during this period are the plutonic masses of granite, dorite, anorthosite, and monzonite.
However, there were already water deposits (and therefore water vapor in the atmosphere ) that contributed to the very gradual cooling of the planet. Also contributing was the fact that the sun was 30% dimmer than it is today .
It was the cause of some of the large craters that can be seen on the latter (and even on Mercury ). These meteors would have contributed additional energy charges that increased the Earth's temperature and were partially responsible for the slow cooling of the planet.
The first fossils of life forms are of bacterial origin (archaebacteria). These early forms of prokaryotic life, we might call blue-green algae, they performed a anoxygenic photosynthesis: not release oxygen to the environment , as do today the bacteria green of the sulfur and purple bacteria.
However, at some point in the Neoarchic, 2.8 billion years ago, photosynthesis as we know it began. Thus, free oxygen began to be released into the atmosphere.
It is believed to have formed from two archaic cratons called Kaapvaal (part of South Africa) and Pilbara (part of Australia) . This follows from the geological similarities between these two very distant regions.
The water also flowed from deep ocean basins in which there was an abundant presence of iron , which, unable to oxidize, dissolved. This element was extremely abundant and played a vital role in the appearance of life, but also gave the waters of the sea a reddish color that today would be unrecognizable to us.
This means that cyanobacteria of the Archean anoxygenic photosynthesis conducting a capturing carbon from CO 2 abundant in the atmosphere. With it they formed carbonates, which accumulated and sedimented, forming small rocky constructions that remain until today.
There are fossil stromatolites from almost all geological eras , and they are the oldest evidence of life on the planet. Those from the Archaic aeon are found today in Warrawoona, Australia.
There are also the first eukaryotic life forms and the first multicellular organisms (metazoans) in history.
The above content published at Collaborative Research Group is for informational and educational purposes only and has been developed by referring reliable sources and recommendations from technology experts. We do not have any contact with official entities nor do we intend to replace the information that they emit.