Created by Jasmine Suero; E Period Earth Systems/Space; October 10, 2014; This is my science project over all the eons of Earth and major events that occurred within them.
After the Big Bang, floating space debris compacted in some areas to form asteroids, solar systems, stars, and even planets as awe-inspiring as our planet Earth. 4.6 billion years ago, when our timeline begins, the Earth looked nothing like it did in modern times. From its molten state, to the introduction of water and life, to troubling pollution, our Earth has gone through many stages.
Earth's satellite, the moon, has been orbiting us almost as long as Earth has existed itself. When a large asteroid collided with Earth, the debris began orbiting Earth and eventually unified into a the moon we see today. Bombardment from other space bodies made the moon's craters, basins, and other identifying features. The moon is responsible for regulating Earth's currents, climate, and animal life cycles.
The water that fills the ocean was deposited on Earth by two methods: outgassing from Earth's molten state, and bombardment by space objects hitting Earth. As these processes continued on, enough water had been deposited to form the oceans we see today. They existed mainly as water vapor but condensed when the planet had cooled down. The same processes that created our oceans also deposited foreign minerals. The geochemical cycles of the ocean have remained virtually unchanged for over billion years.
The first life on Earth existed as single-celled organisms called cyanobacteria that lived around deep sea geothermal vents. These organisms are what all life evolved from today, and they are still a living species. These bacterium-like life forms lacked a nucleus and were the only life on Earth for over a billion years.
The oxygen that went on to occupy Earth's atmosphere (which was composed of methane, ammonia, carbon, and water vapor) was photosynthesized by stromatalites, or blue-green algae, that filled the oceans. This accumulation brought on many changes to Earth, and impacted future life irrefutably. The oxygen in the atmosphere also caused the first mass extinction. Bacterium that were not suited for the air component were poisoned by it.
The first Ice Age, also known as the Huronian glaciation, occurred during the Proterozoic Eon. This ice age occurred when only simple, unicellular life forms existed on Earth, so little was impacted by it. The Huronian was one of the longest and most severe ice ages in Earth's history. It is believed to of been caused by the Great Oxygenation Event, when oxygen accumulated in the atmosphere and killed off many species. This led to a decrease of methane in the atmosphere, therefore decreasing Earth's temperatures.
Tiktaalik is a fossil fish that was found in 2004 in Canada. It is believed to of been the first fish to venture out into land. With a mix of amphibian, reptilian, and mammalian traits, it's no wonder scientists marvel at the evolutionary breakthrough. Tiktaalik is believed to be the precursor to many species that live today, even humans.
The Carboniferous time period was a time when Earth was very organically rich and lush. The Earth looked like a giant bog. The climate was very tropical and humid, and many tetropods evolved during this time, making it a period of interest for scientists. As the matter died and underwent immense heat and pressure, peat, lignite, then coal formed. Many of the coal deposits we see today formed from the remains of this time.
Pangaea was the large super-continent that once was all the landmass on Earth. Evidence for this is shown through our fossil records and other ways. Alfred Wegener originally proposed the idea that the continents used to be merged as one. Tectonic plates, which made up Pangaea, were shifted as convection currents in the mantle below it forced them apart. Over a period of millions of years, the plates moved and formed the map we see today.
Dinosaurs, the massive creatures of prehistoric Earth, lived long ago and thrived in their reign. Dinosaur species were all vastly unique and suited for their environments. Almost 65 million years ago an asteroid hit Earth, killing the dinosaurs in a few different ways. Some died from impact, some died from subsequent shock waves, and some died from the loss of food material, due to the darkening of the atmosphere. Smaller and more equipped to survive species burrowed underground or hid in bodies of water to escape the heat. These species went on to evolve into animals we see today.
Although many consider the first mammals to of emerged shortly after the extinction of the dinosaurs, new fossil evidence suggests that mammals led a low-profile existence 150 million years before they were thought to of emerged. The first mammals evolved from Tiktaalik, and were mostly land inhabitants. The mammals present after the extinction of the dinosaurs were small, weasel-like, and easily adaptable. This contributed to their ability to survive on today.
The first human hominids, like Homo erectus and the Neanderthal, were very similar to humans we see today. Humans and apes share a common ancestor, which makes sense, since humans and apes have 98% of the same DNA. As these hominids evolved, they gradually mutated and changed in ways that made them more cognitively sharp, better at making technologies, and able to do what modern humans have done.
The USSR's Sputnik was the first man-made object to orbit Earth. In 1969, the US made the first moon landing of mankind. Today, scientists are working on many missions to get us farther out from Earth, learn new things about our universe, and contribute to the knowledge of our human race.
There are four major eons of Earth's history.
The Hadeon Eon is the oldest eon in Earth's history. No rock record exists from this time, except for select rocks found in Canada. Rocks from other solar systems were possibly deposited during this eon.
The Archean eon, or the Archaeozoic, shows signs of some of the earliest bacteria-like life forms on Earth that were present for over a billion years desolately. Earth's atmosphere was composed mostly of methane, ammonia, hydrogen, and carbon until stromatolites photosynthesized enough oxygen to make the atmosphere support oxygen thriving creatures. The climate of this eon was very hot and wet. Violent lightening storms and continual rain caused by volcanic activity plagued Earth.
This eon shows evidence of some of the first multicelled organisms. Stromatolites were still commonplace, but other life forms were present as well, like archaea that lived where water was very hot and extremely salty. Eukaryotes (cells with a nucleus) came into existence. The first extinction of large scale occured when the oxygen that had built up in the atmosphere poisoned early, primal, life. Also, two ice ages occured during this eon.
The Phanerozoic Eon is the present eon of Earth's history. The Carboniferous period period and time of the dinosaurs and humans is in this eon. Many species have gone extinct in this eon due to the influence of other species, such as the human.