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The history of Earth is divided into four great eons, starting 4,540 mya with the formation of the planet. Each eon saw the most significant changes in Earth's composition, climate and life. Each eon is subsequently divided into eras, which in turn are divided into periods, which are further divided into epochs. Geologic time scale.
The main topics studied in Earth history are paleogeography, paleontology, and paleoecology and paleoclimatology—respectively, past landscapes, past organisms, past ecosystems, and past environments. This chapter will cover (briefly) the origin of the universe and the 4.6 billion year history of Earth.
geologic history of Earth, evolution of the continents, oceans, atmosphere, and biosphere. The layers of rock at Earth’s surface contain evidence of the evolutionary processes undergone by these components of the terrestrial environment during the times at which each layer was formed.
Geologic time, the extensive interval of time occupied by the geologic history of Earth. Formal geologic time begins with the Archean Eon (4.0 billion to 2.5 billion years ago) and continues to the present day.
About 1,000,000,000 years ago, Earth had its first signs of life. Single-celled organisms consumed the sun’s energy. As a waste product, these cyanobacteria eventually filled the oceans and atmosphere with oxygen. Next, an oxygenated atmosphere paved the way for more complex life forms to exist.
Since the Copernican revolution of the 16th century, at which time the Polish astronomer Nicolaus Copernicus proposed a Sun-centred model of the universe (see heliocentric system), enlightened thinkers have regarded Earth as a planet like the others of the solar system.
The geological history of the Earth follows the major geological events in Earth's past based on the geological time scale, a system of chronological measurement based on the study of the planet's rock layers (stratigraphy).
The variety of contending creatures that have come and gone over billions of years, in a sense, paints a picture of the many planets Earth has been: a lava-covered rock with a poisonous atmosphere, an ocean world with the bare beginnings of microbial life, a steaming tropical riot of earth-shaking dinosaurs, or an Ice Age expanse where cave ...
The first 500 million years of Earth’s existence, known as the Hadean Eon, is a critical missing link in understanding how the planet’s atmosphere, oceans, and differentiated layers of core, mantle, and outer crust developed.
The main topics studied in Earth history are paleogeography, paleontology, and paleoecology and paleoclimatology—respectively, past landscapes, past organisms, past ecosystems, and past climates. The changes that have occurred since the inception of Earth are vast and significant.