APril 1 current notes & understanding

The Precambrian Super Eon is from 4.57 billion to 541 million years ago, roughly 88.03% of recorded time. Note that humans have only been on the Earth .007% of recorded time, a miniscule fraction of one percent. 

4.57 billion years ago or 4.57 Ga, is the current estimate or the best guess of a coalesced Earth, where particles of matter gravitated together from the abyss to form the planet. There is much difficulty in estimating these periods as fossil records did not begin until 3.48 Ga. By Carbon dating rocks, the oldest samples of Zircon crystals of which can survive a molten environment have been dated as far back aa 4.4 Ga. Subsequently dating of meteors to determine the age of the solar system. Thus a baseline for the precambrian is logically estimated. The four Eons are established, The Hadean, The Archean, The Proterozoic, The Phaneroic, of which the first three form the Super Eon known as the Precambrian, followed be the Cambrian encompassing the Phaneroic.

4.54 Ga-4.0 Ga, Hadean Eon, after 3 billion years of the planets formation Earth is unrecognizable and mysterious. It is molten and plate tectonics moved much faster. At 4.4 Ga Thea a Mars size planet collides with Earth, most of Thea coalesced with Earth where enough material deflected to form the Earths moon. 4.1 to 3.8 Ga is known as the Hadean Late Heavy Bombardment where the earth and moon are pummelled by meteors and water bearing comets, ere the craters of the moon are evidence of this. 

4.0 Ga-2.5 Ga, Archean Eon, Earth has cooled, the Oceans and land mass is formed, and from space begins to resemble the Earth as we know it today. By 3.8 Ga are the last traces of heavy bombardment. Unicellular life begins deep in the oceans where volcanic vents breed chemical reactions. By 3.8 Ga the fossil records begin. Stromatolites the oldest fossils are small calcareous layered and sediment mounds created by cyanobacteria single celled organisms live through photosynthesis The formation of ancient continents become the scattered Cratons we know today. 

 2.5 Ga- 541 Ma, Proterozoic Eon "Early Life." Newly evolved cyanobacteria through photosynthesis release Oxygen which is at first absorbed by the Oceans. BIFs-Banded Iron Formations are the visible red layered sedimentary streaks seen in sections of rock. The increase of Oxygen in the oceans trigger a mass extinction of Obligate Anaerobes, organisms that cannot live in an oxygen environment, 2.4 Ga known as the Great Oxidation Event. The predominant Carbon Dioxide over taken by oxygen shift the skys color from orange and green to blue Evolution of multicellular life through Endosymbiosis, the combining and sharing between unicellular and eukaryotic cells. The first complex living plants and animals thrive in the Ediacara fauna a 570 Ma old animal fossil record. Active plate tectonics, 1.8-1.5 Ga Nuna the first supercontinent forms, followed by Rodinia 1.1 Ga to 750 Ma. Pannocia breaks off to the south triggering 100 million year glaciation, ushering in Snow Ball Earth 720-635 Ma. Then the earth thaws and life proliferates again. 

541 Ma, The Phaneroic Eon where all the major phylum of life begin from the Cambrian Explosion. It marks the end of the Precambrian Super Eon.