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This article discusses how rocks are formed. There are also articles on physical rock formations, rock layerings , and the formal naming of geologic formations. Terrestrial rocks are formed by three main mechanisms: Sedimentary rocks are formed through the gradual accumulation of sediments: for example, sand on a beach or mud on a river bed. As ...
The use of rock has had a huge impact on the cultural and technological development of the human race. Rock has been used by humans and other hominids for at least 2.5 million years. [22] Lithic technology marks some of the oldest and continuously used technologies. The mining of rock for its metal content has been one of the most important ...
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]
For example, an igneous rock such as basalt may break down and dissolve when exposed to the atmosphere, or melt as it is subducted under a continent. Due to the driving forces of the rock cycle, plate tectonics and the water cycle, rocks do not remain in equilibrium and change as they encounter new environments. The rock cycle explains how the ...
Over two-thirds of mineral species owe their existence to life, [12] but life may also owe its existence to minerals. They may have been needed as templates to bring organic molecules together; as catalysts for chemical reactions; and as metabolites. [1] Two prominent theories for the origin of life involve clays and transition metal sulfides.
The main rock types. Provenance in geology, is the reconstruction of the origin of sediments. The Earth is a dynamic planet, and all rocks are subject to transition between the three main rock types: sedimentary, metamorphic, and igneous rocks (the rock cycle). Rocks exposed to the surface are eventually broken down into sediments.
The 1.6-billion-year-old organisms are believed to have been the first predators on Earth.
Geology – one of the Earth sciences – is the study of the Earth, with the general exclusion of present-day life, flow within the ocean, and the atmosphere. The field of geology encompasses the composition, structure, physical properties, and history of Earth's components, and the processes by which it is shaped.