The earliest and oldest period in the development of the earth's crust is the Archean era. It was at this time that, according to scientists, the first living heterotroph organisms appeared, which used various organic compounds as food. At the end of the Archean era, the formation of the core of our planet took place, the activity of volcanoes was intensively reduced, because of which life began to develop on Earth.
The Archean era began about 4,000,000,000 years ago and lasted about 1.56 billion years. It is divided into four periods: Neoarchean, Paleoarchean, Mesoarchaeus and Eoarchei.
Earth's crust in the Archean Era
In the Neoarchean period, which took place about 4,000 million years ago, the Earth was already formed as a planet. Almost the entire area was occupied by volcanoes that erupted in large quantities of lava. Its hot rivers formed continents, plateaus, mountains and oceanic depressions. The constant activity of volcanoes and high temperatures led to the formation of minerals - ore, copper, aluminum, gold, building stone, radioactive metals, cobalt and iron. About 3.67 billion years ago, the first metamorphic and igneous rocks (granite, anorthosite and diorite) were formed, which were found in various places: the Baltic and Canadian shields, the island of Greenland, etc.
During the Paleoarchean (3.7-3.34 billion years ago), the formation of the first continent - Valbaru, and the single ocean. The structure of the ocean ridges has changed, which led to a gradual increase in the amount of water and a decrease in the amount of carbon dioxide in the Earth’s atmosphere.
Then the Mesoarchaeus followed, during which the supercontinent began to slowly crack. The Neoarchean, which ended about 2.65 billion years ago, forms the mainland mass. This fact speaks of the antiquity of all the continents of our planet.
Climatic conditions and atmosphere
The Archean era was characterized by a small amount of water. Instead of a vast single ocean, there were only shallow basins located separately from each other. The atmosphere consisted mainly of gas (carbon dioxide is the chemical formula of CO2), its density was much higher than the current one. Water temperature reached 90 degrees. There was little nitrogen in the atmosphere, about ten to fifteen percent. There was practically no methane, oxygen and some other gases. The temperature of the atmosphere itself, according to scientists, reached 120 degrees.
Archean era: biology
During this era, the nucleation of the first protozoa occurs. Anaerobic bacteria became the first inhabitants of the Earth. The first photosynthetic organisms appeared in the Archean era - cyanobacteria (pre-nuclear) and blue-green algae, which began to release free oxygen into the atmosphere from the Earth’s ocean. This contributed to the emergence of living organisms that can survive in an oxygen environment.
But the Archeozoic era is important not only the emergence of photosynthesis. At this time, two more important evolutionary events take place: multicellularity and the sexual process appear, which sharply increased adaptation to environmental conditions due to the creation of many chromosome combinations.