Earth Formation Timeline

The Beginning

Approximately 4.54 billion years ago the earth was in its infancy when a nebula went through accretion. Accretion is the process of things running into each other and progressively getting bigger. Earth began as a ball of molten lava, which made the planet uninhabitable for any life form.

• As the planet formed heavier materials such as iron began to sink, resulting in the Earth becoming denser as you got closer to the center.
• Lighter materials made up the Earth's top layer later cooling to form the crust.
• Earth's original atmosphere also consisted mainly of nitrogen,

ammonia, and carbon dioxide.

Layer Formation

Approximately 4.5 billion years ago the Earth's layers began to form. These major layers include:

• Inner core
• Outer core
• Mantle
• Crust

These layers formed due to heavier materials "sinking" to the center of the Earth and lighter materials "floating" to the surface.

The Planet Cools

The Earth began to cool once our moon collided into our planet. The moon helped stabilize our seasons and took our "6 hour days to 24 hours" (earthhow.com). The cooling also started because eventually the Earth started to loose its energy/heat to space. This resulted in the formation of the crust.

• Oceans and Continents (which started off as volcanic islands) started to form as the Earth cooled. Water came from volcanoes, asteroids, and comets.
• Life began to form as bacteria (cyanobacteria) was able to gain food and energy from the sun only to release oxygen, forming the atmosphere.
• Bacteria came from underwater vents, which contained large

amounts of heat and provided a constant environment, perfect

for the formation of life.

Formation of Earth's Magnetic Field

The formation of Earth's magnetic field was/is very crucial to the development of life on Earth because it kept harmful radiation away. Earth's magnetic field keeps solar radiation from hitting its surface because too much solar radiation would sanitize the planet, killing all bacteria.

Species Evolution

Cambrian Explosion: This era was only the beginning for all life forms. During this time hard-shelled invertebrates came to life in oceans. Followed by the Age of Fish then the first invertebrate formed on land.

• Once invertebrates formed the Age of Amphibians came next.

Paleozoic Era: During this time, rainforests began to thrive. But, due to global warming the vast jungles became deserts when plants and swamps where buried.

• This also turned into underground coal deposits.
• This era ended in a mass extinction

Formation of the Atmosphere

In the beginning Earth's atmosphere was made up of a mixture of Nitrogen, ammonia, and Carbon Dioxide. Later forming into a balance of Co2 and oxygen. Since cyanobacteria was the first dominant species on Earth, they gave off a large amount of oxygen creating not only a thickened ozone layer but also a problem. Cyanobacteria didn't need oxygen to survive instead, they relied on other gases in the atmosphere and sunlight to flourish.

• Due to an abundance of oxygen in the atmosphere at the time multicellular organisms began to form.
• Life forms at this time could only survive in water because it helped protect them from radiation.

"The Age of Mammals and Homo Sapiens"

Before humans, scientists believe that dinosaurs once roamed this planet only to become extinct after an asteroid impacted the Earth. This affected the temperature of the planet, cooling due to the dust from the impact. Once dinosaurs where gone, mammals began to take over. Eventually humans evolved and have become the dominate species of Earth that continue to learn and grow as they evolve, just like any other object in the universe.