The history of the development of Earth's nature

Four broad stages are distinguished in Earth's history: astronomical (the planet formed about 4.6 billion years ago from a cloud of gas and dust), geological (development of the crust, volcanism and tectonic movements), biological (life appeared about 3.5–3.8 billion years ago) and anthropogenic (the stage of humans and their society). The teaching about the order and age of rocks is called geochronology. Relative age is found from the order of layers (when undisturbed, the lower layer is older), and the palaeontological method uses fossils. The geochronological scale runs from the largest unit to the smallest: supereon, eon, era, period, epoch, age. The latest eon is the Phanerozoic, which began about 539 million years ago and is divided into the Paleozoic, Mesozoic and Cenozoic eras; the earlier part is called the Precambrian. In the Cenozoic (from about 66 million years ago) the Paleogene, Neogene and Quaternary (anthropogenic) periods have passed. Through the movement of continents a huge landmass, Pangaea, formed at the end of the Paleozoic and later broke apart again; Earth's nature changed as a result.