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Solidified lava flow in Hawaii Sedimentary layers in Badlands National Park, South Dakota Metamorphic rock, Nunavut, Canada. Geology (from Ancient Greek γῆ (gê) 'earth' and λoγία () 'study of, discourse') [1] [2] is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. [3]
It is widely believed that the early Earth was dominated by vertical tectonic processes, such as stagnant lid, [19] [20] heat-pipe, [21] or sagduction, [22] [23] [24] which eventually transitioned to plate tectonics during the planet's mid-stage evolution. However, an alternative view proposes that Earth never experienced a vertical tectonic ...
Historical geology examines the vastness of geologic time, measured in billions of years, and investigates changes in the Earth, gradual and sudden, over this deep time. It focuses on geological processes, such as plate tectonics, that have changed the Earth's surface and subsurface over time and the use of methods including stratigraphy ...
Pull-apart basin – Type of basin in geology; Quarry – A place from which a geological material has been excavated from the ground; Rift – Part of a volcano where a set of linear cracks form; Sea cave – Cave formed by the wave action of the sea and located along present or former coastlines
Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...
The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronology (a scientific branch of geology that aims to determine the age of rocks).
He argued that most geological change had been very gradual in human history. Lyell provided evidence for Uniformitarianism, a geological doctrine holding that processes occur at the same rates in the present as they did in the past and account for all of the Earth's geological features. [29]
The first eon in Earth's history, the Hadean, begins with the Earth's formation and is followed by the Archean eon at 3.8 Ga. [2]: 145 The oldest rocks found on Earth date to about 4.0 Ga, and the oldest detrital zircon crystals in rocks to about 4.4 Ga, [34] [35] [36] soon after the formation of the Earth's crust and the Earth itself.