4.6 bln years ago:
Earth forms & starts as a clump of dust, that gets struck by lightning! turns into rock, clumps with other asteroids and becomes a big ball.
4.5 by ago:
protoplanet Theia collides with earth, creates moon.
first atmosphere forms, made of gases, like hydrogen & helium, gets blasted away by solar wind. volcanoes create new atmosphere made of Sulpher & carbon dioxied.
crust forms on molten earth. oceans form, supplied by asteroids 2.5 AU away.
first single-celled organisms appear.
first actual plants appear. starts pumping out oxygen. pros: we get to live. cons: most life survives with methane & carbon dioxide @ this time, so massive dieoffs.
great oxygenation crisis. (see above)
snowball earth forms. according to Wikipedia:
The natural evolution of the Sun made it progressively more luminous during the Archean and Proterozoic eons; the Sun’s luminosity increases 6% every billion years.:165 As a result, the Earth began to receive more heat from the Sun in the Proterozoic eon. However, the Earth did not get warmer. Instead, the geological record suggests it cooled dramatically during the early Proterozoic. Glacial deposits found in South Africa date back to 2.2 Ga, at which time, based on paleomagnetic evidence, they must have been located near the equator. Thus, this glaciation, known as the Huronian glaciation, may have been global. Some scientists suggest this was so severe that the Earth was frozen over from the poles to the equator, a hypothesis called Snowball Earth.
wow, so sciency!
basically the earth was snowball earth because of less methane. methane is a great greenhouse gas, and removing it could make it really cold. that’s what happened.
the first alge emerges, which doesn’t help the oxygenation crisis.
1000 million years ago:
supercontinent Rodina forms.
Cambrian explosion brings a lot of life to the planet. here is Wikipedia again:
The rate of the evolution of life as recorded by fossils accelerated in the Cambrian period (542–488 Ma). The sudden emergence of many new species, phyla, and forms in this period is called the Cambrian Explosion. The biological fomenting in the Cambrian Explosion was unpreceded before and since that time.:229 Whereas the Ediacaran life forms appear yet primitive and not easy to put in any modern group, at the end of the Cambrian most modern phyla were already present. The development of hard body parts such as shells, skeletons or exoskeletons in animals like molluscs, echinoderms, crinoids and arthropods (a well-known group of arthropods from the lower Paleozoic are the trilobites) made the preservation and fossilization of such life forms easier than those of their Proterozoic ancestors. For this reason, much more is known about life in and after the Cambrian than about that of older periods. Some of these Cambrian groups appear complex but are seemingly quite different from modern life; examples are Anomalocaris and Haikouichthys. More recently, however, these seem to have found a place in modern classification.
That is it for pt 1, I will do part 2 soon.