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Earth formed about 4.54 billion years ago by accretion from the solar nebula, a disk-shaped mass of dust and gas left over from the formation of the Sun, which also created the rest of the Solar System. Initially, Earth was molten due to extreme volcanism and frequent collisions with other bodies.
1903 – George Darwin and John Joly claim that radioactivity is partially responsible for the Earth's heat; 1907 – Bertram Boltwood proposes that the amount of lead in uranium and thorium ores might be used to determine the Earth's age and crudely dates some rocks to have ages between 410 and 2200 million years
The geologic time scale, proportionally represented as a log-spiral with some major events in Earth's history. A megaannus (Ma) represents one million (10 6) years.. The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth.
5th century BC: The earliest documented mention of a spherical Earth comes from the Greeks in the 5th century BC. [31] It is known that the Indians modeled the Earth as spherical by 300 BC [32] 460 BC: Empedocles describes thermal expansion. [33] Late 5th century BC: Antiphon discovers the method of exhaustion, foreshadowing the concept of a limit.
The geologic record is the strata (layers) of rock in the planet's crust and the science of geology is much concerned with the age and origin of all rocks to determine the history and formation of Earth and to understand the forces that have acted upon it.
The Earth's strata can be defined as horizontal layers of rock having approximately the same composition throughout. [10] An important pioneer in the science was Nicolas Steno. Steno was trained in the classical texts on science; however, by 1659 he seriously questioned accepted knowledge of the natural world. [11]
The geological time scale (GTS), as defined by international convention, [3] depicts the large spans of time from the beginning of the Earth to the present, and its divisions chronicle some definitive events of Earth history. Earth formed around 4.54 billion years ago, approximately one-third the age of the universe, by accretion from the solar ...
Map of the later North Atlantic region after the closing of the Iapetus Ocean and the Caledonian/Acadian orogenies (Wilson 1966).Animals: Trilobites and graptolites. [1] [2] Euramerica in the Devonian (416 to 359 Ma) with Baltica, Avalonia (Cabot Fault, Newfoundland and Great Glen Fault, Scotland; cited in Wilson 1962) and Laurentia (Other parts: Iberian Massif and Armorican terrane).