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5 billion years ago
Our solar system was a swirling mass of dust and gas. It was not yet formed, but it was in the beginning process. -
4.6 billion years ago
Earth began to form and grow by collecting colliding space debris. What happened was a cloud of debris from the big bang was left in the area o the milky way galaxy. This debris was collected by the gravitational force into the center of the cloud until it had to burst because it was far to dense. The. The planets and other systems were formed from what the sum didn't take up. -
4 billion years ago
-Volcanoes start to form an atmosphere on Earth. This happens because the earth was still in it's early stages of development and the molten rock underneath the mantle and the crust above unstable causing chemicals from the earths interior to spill out in these volcanoes. -Cellular life also started to develop at this time. The Archaea we know today is thought to be smiliar to the types of cellular life that was on the Earth 4 billion years ago. -
3.5 billion years ago
Fossils of stromatolites are as old as 3.5 billion years. These rocks are important because they record some of the earliest types of life on Earth in forms such as bacteria and other microorganisms. -
3 billion years ago
Life forms on Earth become photosynthetic by this time. Bacteria started producing oxygen from water, and turning CO2 into carbohydrates. -
2.2 billion years ago
The Earth's appearance was probably much like it was today. Most of the earths crusts were done moving and the molten exterior was hardening. Most of the earths crusts were done moving and the molten exterior was hardening. The plates began to settle into place. This led to the existence of O2 on earth. -
2 billion years ago
The Earth's oxygen levels reached today's levels. Due to the photosynthetic life forms living on our early planet, Earth was able to develop over time and produce oxygen. -
1.5 billion years ago
Small aerobic prokaryotes began to live and produce inside a larger anaerobic prokaryote.The theory that explains this is called the endosymbiotic theory. -
1 billion years ago
-Ozone (O3) formed – protected organisms from harmful UV rays so they could exist on land. -
Between 1600-1700
Francesco Redi conducts his experiments with maggots and raw meats. He wanted to disprove the theory of spontaneous generation, which was the theory that most people believed in. -
Between 1700-1800
Spallanzani conducts experiments with flasks and broth and his findings agree with Redi and biogenesis. -
Between 1800-1900
In 1952, the Urey and Miller experiment was conducted to test what the conditions were like during the early years of Earth. It is often referred to as the “classic experiment on the origin of life”. It was also conducted to test Oparin’s hypothesis. -
Between 1900-Present
Haldane and Oparin hypthoicize. According to their theory, life evolved in the oceans during a period when the atmosphere was reducing - containing H2, H2O, NH3, CH4, and CO2, but no free O2. Organic compounds were synthesized non-biologically by ultraviolet light energy, which in the absence of an ozone shield would penetrate the upper layers of the ocean.
