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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 . Eon.
Oct 19, 2023 · Earth is one of the four inner, terrestrial planets in our solar system. Just like the other inner planets —Mercury, Venus, and Mars—it is relatively small and rocky. Early in the history of the solar system, rocky material was the only substance that could exist so close to the Sun and withstand its heat.
2 days ago · The early evolution of the solid Earth and its atmosphere and oceans is covered in geologic history of Earth. The geologic and biological development of Earth, including its surface features and the processes by which they are created and modified, are discussed in geochronology, continental landform, and plate tectonics.
- What is Earth?Earth is the third planet from the Sun and the fifth largest planet in the solar system in terms of size and mass. Its near-surface environments ar...
- Where is Earth in the Milky Way Galaxy?Earth is located in the Orion-Cygnus Arm, one of the four spiral arms of the Milky Way, which lies about two-thirds of the way from the centre of t...
- What is Earth named for?Earth’s name in English, the international language of astronomy, derives from Old English and Germanic words for ground and earth, and it is the o...
- What was Earth like when it was first formed?Earth and the other planets in the solar system formed about 4.6 billion years ago. The early Earth had no ozone layer and no free oxygen, lacked o...
- What does Earth look like?Viewed from another planet, Earth would appear bright and bluish in colour. In latitudinal belts, swirling white cloud patterns of midlatitude and...
- Origin of The Universe
- Hadean Eon
- Archean Eon
- Proterozoic Eon
- Phanerozoic EON: Paleozoic Era
- Phanerozoic EON: Mesozoic Era
- Phanerozoic EON: Cenozoic Era
- Summary
The universe appears to have an infinite number of galaxies and solar systems and our solar system occupies a small section of this vast entirety. The origins of the universe and solar system set the context for conceptualizing the Earth’s origin and early history.
Geoscientists use the geological time scale to assign relative age names to events and rocks, separating major events in Earth’s history based on significant changes as recorded in rocks and fossils. This section summarizes the most notable events of each major time interval. For a breakdown on how these time intervals are chosen and organized, see...
Late Heavy Bombardment
Objects were chaotically flying around at the start of the solar system, building the planets and moons. There is evidence that after the planets formed, about 4.1–3.8 billion years ago, a second large spike of asteroid and comet impacted the Earth and Moon in an event called late heavy bombardment. Meteorites and comets in stable or semi-stable orbits became unstable and started impacting objects throughout the solar system. In addition, this event is called the lunar cataclysm because most...
Origin of the Continents
The first solid evidence of modern plate tectonics is found at the end of the Archean, indicating at least some continental lithosphere must have been in place. This evidence does not necessarily mark the starting point of plate tectonics; remnants of earlier tectonic activity could have been erased by the rock cycle. The stable interiors of the current continents are called cratons and were mostly formed in the Archean Eon. A craton has two main parts: the shield, which is crystalline baseme...
First Life on Earth
Although the origin of life on Earth is unknown, hypotheses include a chemical origin in the early atmosphere and ocean, deep-sea hydrothermal vents, and delivery to Earth by comets or other objects. One hypothesis is that life arose from the chemical environment of the Earth’s early atmosphere and oceans, which was very different than today. The oxygen-free atmosphere produced a reducing environment with abundant methane, carbon dioxide, sulfur, and nitrogen compounds. This is what the atmos...
An oxygenated world also changed the chemistry of the planet in significant ways. For example, iron remained in solution in the non-oxygenated environment of the earlier Archean Eon. In chemistry, this is known as a reducing environment. Once the environment was oxygenated, iron combined with free oxygen to form solid precipitates of iron oxide, su...
Life in the early Paleozoic Era was dominated by marine organisms but by the middle of the era plants and animals evolved to live and reproduce on land. Fish evolved jaws and fins evolved into jointed limbs. The development of lungs allowed animals to emerge from the sea and become the first air-breathing tetrapods (four-legged animals) such as amp...
8.7.1 Mesozoic Tectonics and Paleogeography
This age pattern shows how the Atlantic Ocean opened as the young Mid-Atlantic Ridge began to create the seafloor. This means the Atlantic ocean started opening and was first formed here. The southern Atlantic opened next, with South America separating from central and southern Africa. Last (happening after the Mesozoic ended) was the northernmost Atlantic, with Greenland and Scandinavia parting ways. The breaking points of each rifted plate margin eventually turned into the passive plate bou...
8.8.1 Cenozoic Tectonics and Paleogeography
Animation of the last 38 million years of movement in western North America. Note, that after the ridge is subducted, convergent turns to transform (with divergent inland).
The changes that have occurred since the inception of Earth are vast and significant. From the oxygenation of the atmosphere, the progression of life forms, the assembly and deconstruction of several supercontinents, to the extinction of more life forms than exist today, having a general understanding of these changes can put present change into a ...
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Apr 30, 2024 · Parts of the mantle are molten, meaning they are composed of partly melted rock. The mantle’s molten rock is constantly in motion. It is forced to the surface during volcanic eruptions and at mid-ocean ridges. Earth’s crust is the planet’s thinnest layer, accounting for just one percent of Earth’s mass.
Apr 8, 2022 · This process created our solar system's asteroids, comets, planets and moons. Earth's rocky core formed first, with heavy elements colliding and binding together. Dense material sank to the ...
Apr 5, 2024 · 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.
