Geologic Time Scale

Scientists during the time of the Great Inventing created a scale named the Geologic Time Scale to determine the history of Earth. Based on findings, they created a scale that was separated into different divisions called eons, eras, periods & epochs. They also adopted the term "supereon" to account the timeline that contained the majority of eons in the Earth's history.

Chaotian Eon
The eon prior to the start of the Hadean & the Precambrian Supereon is the Chaotian. The Chaotian was recognized as the time before the formation of Earth & spans from the time of the Big Bang at the beginning of the universe 14 billion years before the present up to about 5 to 4.6 billion years ago when the Earth formed.

Precambrian Supereon
The Precambrian Supereon is all time before the Cambrian Explosion in the Cambrian Period of the Paleozoic Era of the Phanerozoic Eon. It depicts 90% of the entire history of Earth.

Hadean Eon
As a newborn planet, Earth was a giant molten ball of fire with an atmosphere that had little or no oxygen. After about 100 million years after it's creation, the Moon was captured & put into an orbit over the Earth. The Earth then cooled to form a crust over the next 600 million years. 3.9 billion years ago, the Earth entered the Late Heavy Bombardment, when meteors attacked the Earth & supplyed water for the world's oceans. During the Bombardment that lasted 100 million years, the Moon distanced from Earth, slowing the planet's rotation & lowering tides.

Archean Eon
3.8 billion years ago, in the oceans, bacteria appeared as the first life. Over time, they began evolving into newer prokaryotic (unicellular) organisms, becoming cyanobacteria, which cemented with minerals from the rocks on the seabeds in shallow waters to become a structure called stromatolites. Cyanobacteria, using photosynthesis, created oxygen over the next 2 billion years.

Proterozoic Eon
Stromatolites from the Archean continued to create oxygen for the atmosphere. At the end of the Mesoproterozoic Era, the Earth generated heat that made the mantle break the crust into plates that made islands collide & merge. 1 billion years ago, the plates formed the first supercontinent in Earth's history, Rodinia. Rodinia existed for about 350 million years before it broke apart. 558 million years ago, global cooling, caused by volcanic activity spawned from the breakup of Rodinia, starts Snowball Earth, a fifteen million year long ice age that was the longest & coldest in Earth's history. 543 million years ago, the Earth's volcanoes break the surface of the ice & warm the atmosphere.

Cambrian
The Cambrian began with the intense spawning of eukaryotic (multicellular) life. Prior to the recently concluded Snowball Earth, the only life on Earth was prokaryotic cells of bacteria that lived in the oceans. In the oceans, newer life forms appeared, such as wiwaxia, pikaia, anomalocaris & elrathia, the first species of the trilobites. All life is under the ocean.

Ordovician
The Ordovician continued with life in the oceans. Life continued to evolve under the waves while the tectonic plates shifted again. This time, they formed the second supercontinent, Gondwana. This supercontinent mostly contained areas such as present day Wildwood, the Big Apple & Storm Island while missing other chunks of land such as the Ovalia & Siberia.

Silurian
In the Silurian, the ozone layer began to develop to block out ultraviolet radiation while life continued evolution under the waves.

Devonian
Most of the Devonian Period, life was in the water. However, the ozone layer closes up & shields the Earth from radiation. With no UV light getting to the surface of the Earth, life moves onto land, spawning newer life forms.

Pennsylvanian
The movement & evolution of life on land in Gondwana continues. In this time, Ovalia & Siberia collide with Gondwana & merge. The oxygen in the atmosphere was greater than it is in the Holocene, making most animals giants. However, some creatures, such as mammals, end up being small, such as the ottsels, which appear in the Middle Pennsylvanian.