I will to dedicate this book to elementary school students because I would like them to learn a little about early earth and the 4 different era’s

Earth was formed approximately 4.6 billion years ago, the solar system was a cloud of dust and gas known as a solar nebula. Gravity collapsed the material in on itself as it began to spin, forming the sun in the center of the nebula.

Table of contents

Chapter 1 - Precambrian era

Chapter 2 - Paleozoic era

Chapter 3 - Mesozoic era

Chapter 4 - Cenozoic era

Chapter 1

Precambrian era

This Era happened around 3.5 billion years ago and ended 543 million years ago. This era made up 87% of Earth's history. Around 2.7 billion years ago organisms developed the ability to photosynthesis. Scientist separate this era into 3 distinct eons called the Hadean, the Archean, and the Proterozoic because scientists have a hard time getting information from the rocks. This Era was also the longest era In Earths History.

The Hadean Eon

begins when the Earth formed from swirling dust and gas coalescing into a sphere about 4.56 billion years ago and continues all throughout the geological development of the planet. During this time, Earth had impact craters all over it from asteroids and other celestial bodies crashing into it; had oceans that weren’t filled with water but were instead filled with boiling, liquid rock and had air that was filled with sulfur, carbon dioxide, and dust.

The Archean Eon

began approximately 560 million years after the formation of the Earth. During this time, the planet isn’t a living hell like it was during the Hadean Eon. For the most part, the Earth has cooled down and the water vapor that was locked in the atmosphere had begun to cool and condense into massive oceans. A large portion of the carbon dioxide that was a main component of the atmosphere during the last eon, was chemically alter and became limestone for the ocean floor.

The Proterozoic Eon

began about 2 billion years ago, which is approximately 2 billion years after the formation of the Earth. During this time, Earth was moving toward becoming a planet with a more oxygenated atmosphere. It was also the time when several glaciations occurred—which many scientists believe led to Snowball Earth, although at this point it’s still a hypothesis. Single celled organisms named eukaryotes also began to gain prominence during this period and this was also the time when multi-celled life really began to evolve; both probably as a result of the free oxygen that was now available in the atmosphere.

Chapter 2

Paleozoic Era

The Paleozoic Era lasted around to 544 to 245 million years and is also divided into six periods. A lot of events happened in this Era for an example there were two ice ages and there was an evolution of fish, reptiles, insects and many more. Near the end of the Paleozoic era there was the largest mass extinction on fossil records. 90% of marine life went extinct and 70% of land species went extinct.

Cambrian time period

The Cambrian period is an important point in the history of life on Earth as it is the time where most group of animals appear. This period lasted around 53 million years and made a huge change in life on Earth, known as the Cambrian Explosion. The Cambrian Explosion was an event when most major animals appeared in the fossil record and this event is what added the animals.

Ordovician time period

Ordovician is the second period in the Poleozoic era and It began 485.4 million years ago and ended 443.8 million years ago. Something that happened is that ordovician rocks were first found in wale rocks. Ordovician was named after the Celtic tribe of the Ordovices.

Silurian time period

Silurian period is the third period of the Paleozoic era. The Silurian Period occurred from 443 million to 416 million years ago. The glaciers started to melt more since the climate in this period was more warmer and it caused the seas to rise. Coral reefs began to evolve during this time and mosses and other plants began to grow.

Devonian time period

This is the fourth period of the Poleozoic Era. This period occurred from about 419.2 million and 358.9 million years ago. During this time the climate was warm and the land mass changed as well. Marine animals have also developed with jaws,gills, and fins.

Carboniferous time period