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Earth's formation and evolution. Approximately 4.6 billion years ago, the solar system was a cloud of dust and gas known as a solar nebula. ... Earth's rocky core formed first, with heavy elements colliding and binding together. Dense material sank to the center, while the lighter material created the crust.
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The inner core is Earth's deepest layer. It is a ball of solid iron just larger than Pluto which is surrounded by a liquid outer core. The Earth’s upper mantle is mostly made up of silicon oxide or “silicate” and a mixture of iron and magnesium oxide. At high temperatures, a metallic melt containing iron forms between grains of the silicate crystals because it has a lower melting point. https://physicsworld.com/a/how-the-earths-core-was-formed/
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The prevailing theory supported by the scientific community, the giant impact hypothesis suggests that the moon formed when an object smashed into early Earth. Like the other planets, Earth formed from the leftover cloud of dust and gas orbiting the young sun.
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Jack Hills zircon is best known as the source of the oldest material of terrestrial origin found to date. that zircon crystals from Western Australia’s Jack Hills region crystallized 4.4 billion years ago, strengthening the theory of a ‘cool early Earth,’ where temperatures were low enough for liquid water, oceans and a hydrosphere not long after the planet’s crust congealed from a sea of molten rock.
https://earthsky.org/earth/this-zircon-crystal-is-the-oldest-piece-of-earths-crust -
The Acasta gneiss: Earth's oldest surface rock. Acasta Gneiss: at approximately 4.03 billion years-old, the tonalite gneiss is the oldest rock exposed on the surface of the planet.Courtesy Mark RyanI recently attended a geology seminar sponsored by the Geological Society of Minnesota. https://journals.lib.unb.ca/index.php/GC/article/view/3966
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The geologic record shows evidence for early life in two ways: 1) carbon isotopes, and 2) fossil stromatolites. The isotope evidence significantly predates the fossils. One difficulty in identifying the earliest evidence of life is that most of the rocks from this period have been destroyed by erosion and plate tectonics. Geologists find rocks of this antiquity in only a few places in the world, such as Western Australia and Greenland. https://ncse.com/library-resource/earliest-evidence-life
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Surface of Earth changed from molten to solid rock. Water started condensing in liquid form. https://www.researchgate.net/publication/31323729_High-Pressure_Dehydration_Melting_of_Metapelites_Evidence_from_the_Migmatites_of_Yaounde_Cameroon
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First simple cells, oxygen-producing bacteria. https://en.wikipedia.org/wiki/History_of_Earth
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Ancient Life: Apex Chert Microfossils. This slide shows pictures of some of the oldest known fossils from Earth, bacteria fossils from the Apex Chert in Western Australia. Approximately 3.5 billion years ago, this rock was sediment on the floor of an ancient lake or ocean.
https://en.wikipedia.org/wiki/History_of_Earth -
the atmosphere was largely or entirely devoid of oxygen. So were the oceans, with the possible exception of oxygen oases in the shallow oceans. Around 2.45 million years ago, atmospheric oxygen levels rose sharply, leveling out around 1.85 million years ago. The shallow oceans became mildly oxygenated, while the deep oceans continued to be anoxic.
https://en.wikipedia.org/wiki/History_of_Earth -
Bacteria and Archaea, which are prokaryotes, are single-celled organisms of quite a different type and do not have nuclei. Cell nuclei were first found by Antonie van Leeuwenhoek in the 17th century. The nucleus has a membrane around it but the things inside it do not.
https://en.wikipedia.org/wiki/History_of_Earth -
Sexual reproduction appeared, increasing the rate of evolution. https://en.wikipedia.org/wiki/History_of_Earth
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Meteor impact, 170 km crater Chicxulub, Yucatan, Mexico.
Mass extinction of 80-90% of marine species and 85% of land species.
Dinosaurs became extinct.
Mammals became dominant species. Rapid diversification in ants. -
