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4.6 Billion years ago to 543 Million years ago. This is known for the development of microscopic fossils. It includes the Hadeaon, Archaean, and Proterozoic periods. |
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4.5 to 3.8 Billion years years ago. This predates the appearance of the oldest known rocks. It is thought that chemical evolution and the origins of life occurred in this period.
3.8 to 2.5 Billion years ago. Earliest fossils.
2.5 Billion years to 548 Million years. Transition to oxygen atomsphere. Development of multi-celled organisms.
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This is connected first to physics, chemistry, astronomy, earth science, and other areas of biology including molecular biology, cell biology, organism biology, systematics, and ecology. Precambrian life is followed by Paleozoic life. Other areas of knowledge such as personal studies, anthropology, culture, institutions, sociology, and history will be connected as this site develops. |
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