Geology 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. Modern geology significantly overlaps all other Earth sciences, including hydrology. It is integrated with Earth system science and planetary science.
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than 150 to 200 °C and, often, elevated pressure of 100 megapascals (1,000 bar) or more, causing profound physical or chemical changes. During this process, the rock remains mostly in the solid state, but gradually recrystallizes to a new texture or mineral composition. The protolith may be an igneous, sedimentary, or existing metamorphic rock.
In geology, rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition, and the way in which it is formed. Rocks form the Earth's outer solid layer, the crust, and most of its interior, except for the liquid outer core and pockets of magma in the asthenosphere. The study of rocks involves multiple subdisciplines of geology, including petrology and mineralogy. It may be limited to rocks found on Earth, or it may include planetary geology that studies the rocks of other celestial objects.
A volcanologist, or volcano scientist, is a geologist who focuses on understanding the formation and eruptive activity of volcanoes. Volcanologists frequently visit volcanoes, sometimes active ones, to observe and monitor volcanic eruptions, collect eruptive products including tephra, rock and lava samples. One major focus of inquiry in recent times is the prediction of eruptions to alleviate the impact on surrounding populations and monitor natural hazards associated with volcanic activity. Geologists who research volcanic materials that make up the solid Earth are referred to as igneous petrologists.
Economic geology is concerned with earth materials that can be used for economic and industrial purposes. These materials include precious and base metals, nonmetallic minerals and construction-grade stone. Economic geology is a subdiscipline of the geosciences; according to Lindgren (1933) it is “the application of geology”. It may be called the scientific study of the Earth's sources of mineral raw materials and the practical application of the acquired knowledge.
Petrology is the branch of geology that studies rocks and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology. Igneous and metamorphic petrology are commonly taught together because both make heavy use of chemistry, chemical methods, and phase diagrams. Sedimentary petrology is commonly taught together with stratigraphy because it deals with the processes that form sedimentary rock. Modern sedimentary petrology is making increasing use of chemistry.
Skarns or tactites are coarse-grained metamorphic rocks that form by replacement of carbonate-bearing rocks during regional or contact metamorphism and metasomatism. Skarns may form by metamorphic recrystallization of impure carbonate protoliths, bimetasomatic reaction of different lithologies, and infiltration metasomatism by magmatic-hydrothermal fluids. Skarns tend to be rich in calcium-magnesium-iron-manganese-aluminium silicate minerals, which are also referred to as calc-silicate minerals. These minerals form as a result of alteration which occurs when hydrothermal fluids interact with a protolith of either igneous or sedimentary origin. In many cases, skarns are associated with the intrusion of a granitic pluton found in and around faults or shear zones that commonly intrude into a carbonate layer composed of either dolomite or limestone. Skarns can form by regional or contact metamorphism and therefore form in relatively high temperature environments. The hydrothermal fluids associated with the metasomatic processes can originate from a variety of sources; magmatic, metamorphic, meteoric, marine, or even a mix of these. The resulting skarn may consist of a variety of different minerals which are highly dependent on both the original composition of the hydrothermal fluid and the original composition of the protolith.
The following outline is provided as an overview of and topical guide to Earth science:
Fractional crystallization, or crystal fractionation, is one of the most important geochemical and physical processes operating within crust and mantle of a rocky planetary body, such as the Earth. It is important in the formation of igneous rocks because it is one of the main processes of magmatic differentiation. Fractional crystallization is also important in the formation of sedimentary evaporite rocks or simply fractional crystallization is the removal of early formed crystals from an Original homogeneous magma so that the crystals are prevented from further reaction with the residual melt.
The Geological Association of Canada (GAC) is a learned society that promotes and develops the geological sciences in Canada. The organization holds conferences, meetings and exhibitions for the discussion of geological problems and the exchange of views in matters related to geology. It publishes various journals and collections of learned papers dealing with geology.
The following outline is provided as an overview of and topical guide to geology:
Earth science or geoscience includes all fields of natural science related to the planet Earth. This is a branch of science dealing with the physical, chemical, and biological complex constitutions and synergistic linkages of Earth's four spheres: the biosphere, hydrosphere/cryosphere, atmosphere, and geosphere. Earth science can be considered to be a branch of planetary science but with a much older history.
Igneous rock, or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava.
Bernard Elgey Leake is an English geologist. He is Emeritus Professor of Geology at the University of Glasgow, was Leverhulme Emeritus Fellow at Cardiff University 2000-2002 and has been an Honorary Research Fellow at Cardiff University since 1997.
The China University of Geosciences (Beijing) is a public university located in Beijing, China. It is affiliated with the Ministry of Education, and co-funded by the Ministry of Education and the Ministry of Natural Resources. The university is part of the Double First-Class Construction and Project 211.
The Department of Earth and Environmental Sciences at The University of Manchester is one of the oldest earth and environmental science departments in the UK. The Department takes roughly 100 new undergraduates and 140 postgraduates each year, and employs 90 members of academic staff, 41 postdoctoral researchers, 27 technical staff and 20 administrative staff.
Geological engineering is a discipline of engineering concerned with the application of geological science and engineering principles to fields, such as civil engineering, mining, environmental engineering, and forestry, among others. The work of geological engineers often directs or supports the work of other engineering disciplines such as assessing the suitability of locations for civil engineering, environmental engineering, mining operations, and oil and gas projects by conducting geological, geoenvironmental, geophysical, and geotechnical studies. They are involved with impact studies for facilities and operations that affect surface and subsurface environments. The engineering design input and other recommendations made by geological engineers on these projects will often have a large impact on construction and operations. Geological engineers plan, design, and implement geotechnical, geological, geophysical, hydrogeological, and environmental data acquisition. This ranges from manual ground-based methods to deep drilling, to geochemical sampling, to advanced geophysical techniques and satellite surveying. Geological engineers are also concerned with the analysis of past and future ground behaviour, mapping at all scales, and ground characterization programs for specific engineering requirements. These analyses lead geological engineers to make recommendations and prepare reports which could have major effects on the foundations of construction, mining, and civil engineering projects. Some examples of projects include rock excavation, building foundation consolidation, pressure grouting, hydraulic channel erosion control, slope and fill stabilization, landslide risk assessment, groundwater monitoring, and assessment and remediation of contamination. In addition, geological engineers are included on design teams that develop solutions to surface hazards, groundwater remediation, underground and surface excavation projects, and resource management. Like mining engineers, geological engineers also conduct resource exploration campaigns, mine evaluation and feasibility assessments, and contribute to the ongoing efficiency, sustainability, and safety of active mining projects
Keiko Hattori is a geochemist and mineralogist. She is Distinguished University Professor of Geochemistry and Mineral Deposits in the Department of Earth and Environmental Sciences at the University of Ottawa.
