The earliest and oldest period in the development of the earth's crust is the Archean era. It was at this time, according to scientists, that the first living heterotrophic 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 decreasing, due to 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, Mesoarchean and Eoarchean.
Earth's crust in the Archean Era
During 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, which erupted lava in large quantities. Its hot rivers formed continents, plateaus, mountains and oceanic depressions. The constant activity of volcanoes and high temperatures have led to the formation of minerals - ores, copper, aluminum,gold, building stone, radioactive metals, cob alt 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 B altic and Canadian shields, Greenland, etc.
During the Paleoarchean (3, 7-3, 34 billion years ago) the formation of the first continent - Valbaru, and a single ocean occurs. At the same time, the structure of oceanic ridges has changed, which has 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 followed the Mesoarchean, during which the supercontinent began to slowly break apart. In the Neoarchean, which ended approximately 2.65 billion years ago, the main continental mass is formed. 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 pools located separately from each other. The atmosphere consisted mainly of gas (carbon dioxide - the chemical formula CO2), its density was much higher than the current one. The 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.
Archaean era: biology
During this erathe birth of the first simple organisms. Anaerobic bacteria became the first inhabitants of the Earth. In the Archean era, the first photosynthetic organisms appeared - 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 for the appearance of photosynthesis. At this time, two more important evolutionary events take place: multicellularity and the sexual process appear, which dramatically increased adaptation to environmental conditions due to the creation of many chromosome combinations.
