to form the cores of the continents we know today. If you look closely, you will see evidence of blue-green algae (actually simple bacteria) floating in the ocean. Neoarchean -the fourth and final era in the Archean Eon, occurring after the Mesoarchean Era, and before the Paleoproterozoic Era. Age: 2,800 – 2,500 million years ago Mesoarchean -a geologic era within the Archean Eon, spanning 3,200 to 2,800 million years ago. The era is defined chronometrically and is not referenced to a specific level in a rock section on Earth. Fossils from Australia show that stromatolites have lived on Earth since the Mesoarchean. The Pongola glaciation occurred around 2,900 million years ago.  The first supercontinent Vaalbara broke up during this era about 2,800 million years ago. Animal: stromatolites - longest living organism on Earth. They are sediment trapping, binding, and precipitating of phototrophic microbes. They include cyanobacteria/blue-green algae. It can grow up to be 10 different species of bacteria. Paleoarchean Era The Paleoarchean Era is 3600-3200 million years old. It spans a time when the first supercontinent, Vaalbara, was in formation. The Earth was mostly ocean during this time and was covered in volcanoes that later formed islands which made Vaalbara. During this time, days were about 18 hours long and it was around 26.7 degrees Celsius . The air, unfortunately, would not support much life. It was 0% Oxygen and 9.6-8.12% Carbon Dioxide. The only life at the time was Cyanobacteria which was well preserved in stromatolitites. Eoarchean era This is when the Earth had a solid crust for the first time, lava may have still been on the surface and it’s also the first-time rocks formed. Prokaryotes started to exist at this time, and few other bacteria. Early life used Methane as their energy source. Proterozoic Eon , the younger of the two divisions of Precambrian time, the older being the Archean Eon. The Proterozoic Eon extended from 2.5 billion to 541 million years ago and is often divided into the Paleoproterozoic (2.5 billion to 1.6 billion years ago), the Mesoproterozoic (1.6 billion to 1 billion years ago), and the Neoproterozoic (1 billion to 541 million years ago) eras. Proterozoic rocks have been identified on all the continents and often constitute important sources of metallic ores, notably of iron, gold, copper, uranium, and nickel. During the Proterozoic, the atmosphere and oceans changed significantly. Proterozoic rocks contain many definite traces of primitive life-forms—the fossil remains of bacteria and blue-green algae, as well as of the first oxygen-dependent animals, the Ediacaran fauna. Many mountain belts formed during the Proterozoic. PHANEROZOIC EON PALEOZOIC ERA The Paleozoic Era, which ran from about 542 million years ago to 251 million years ago, was a time of great change on Earth. The era began with the breakup of one supercontinent and the formation of another. Plants became widespread. And the first vertebrate animals colonized land.
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- Geologic Time Scale, Cretaceous–Tertiary extinction event, Geological history of Earth