{"thcode":2,"term":{"code":451,"name":"geologic processes","parent":101,"scope":"All types of processes involving geological structures."},"uf":[{"name":"lithification","usewith":false}],"bt":[{"code":101,"name":"biological and physical processes","parent":1174,"scope":"All continuing activities, functions, and phenomena associated with organisms and non-living matter."},{"code":1174,"name":"topics","parent":1,"scope":"Themes, subjects, and concerns for which USGS information resources are relevant."},{"code":1,"name":"Categories","parent":null,"scope":"Thematic terms for categorizing information resources.  This thesaurus is intended to support finding and understanding scientific information."}],"nt":[{"code":1699,"name":"deformation (geologic)","parent":451,"scope":"Change in form and structure of geologic materials in response to stress, typically heat and pressure."},{"code":248,"name":"diagenesis","parent":451,"scope":"Chemical, physical, and biological changes in sediment during and after its conversion to rock (lithification)."},{"code":1683,"name":"earth tides","parent":451,"scope":"Periodic changes in the earth surface topography caused by the gravitational attraction of the moon and sun, measured with tiltmeters.  Used in studies of volcanic activity."},{"code":304,"name":"earthquakes","parent":451,"scope":"Ground shaking caused by the sudden release of accumulated strain by an abrupt shift of rock along a fracture in the earth or by volcanic or magmatic activity, or other sudden stress changes in the earth."},{"code":353,"name":"erosion","parent":451,"scope":"The process whereby materials of the earth's crust are loosened, dissolved, or worn away and simultaneously moved from one place to another."},{"code":2282,"name":"fluid migration","parent":451,"scope":"Movement or migration of fluids, including petroleum and other chemicals through earth materials by natural or anthropogenic forces."},{"code":482,"name":"glaciation","parent":451,"scope":"The geologic processes involved in the formation, movement, changes, and effects of large ice masses (glaciers)."},{"code":534,"name":"heat flow (earth)","parent":451,"scope":"Energy transferred by a difference in temperature through the surface of the earth."},{"code":562,"name":"hydrothermal processes","parent":451,"scope":"Natural phenomena relating to heated water generated by igneous activity."},{"code":608,"name":"isostasy","parent":451,"scope":"Condition of equilibrium or buoyancy of the earth's crust above the mantle."},{"code":1721,"name":"magnetic storms","parent":451,"scope":"A period of time during which the earth's magnetic field varies rapidly.  During magnetic storms, satellite electronics can be damaged through the build up and subsequent discharge of static electric charges and astronauts and high-altitude pilots can be subjected to increased levels of radiation."},{"code":727,"name":"metamorphism (geological)","parent":451,"scope":"Process by which rocks are altered in composition and texture by extreme heat, high pressure, or the action of chemicals."},{"code":1034,"name":"sediment transport","parent":451,"scope":"Transport of solid particles of unconsolidated rock and mineral fragments, chemical precipitates, or biological materials."},{"code":1036,"name":"sedimentation","parent":451,"scope":"Process of deposition of sediments (loose, uncemented pieces of rock, mineral fragments, or biological materials).  The sediments settle out of water or air into layers on a surface."},{"code":1736,"name":"slope processes","parent":451,"scope":"The down slope movement of earth material under the influence of gravity."},{"code":1710,"name":"soil formation","parent":451,"scope":"Geological, geochemical, and ecological processes that work together to produce soils."},{"code":624,"name":"subsidence","parent":451,"scope":"Settling, compaction, or caving in of land caused by subsurface mining, ground-water withdrawal, or pumping of oil and gas."},{"code":1145,"name":"tectonic processes","parent":451,"scope":"The structural forces affecting the deformation, uplift, and movement of the earth's crust."},{"code":1751,"name":"uplift","parent":451,"scope":"Local or regional rise in the elevation of the land surface, usually due to tectonic or volcanic processes."},{"code":1286,"name":"volcanic activity","parent":451,"scope":"Episodes during which gases, ash, and lava (molten rock) escape from vents in the earth's crust, accompanied by minor tremors."}],"rt":[{"code":464,"name":"geology","parent":291,"scope":"Study of the planet earth, its composition, structure, physical and chemical processes, and history since its origin."},{"code":560,"name":"hydrology","parent":291,"scope":"Branch of earth science that deals with water as it occurs in the atmosphere, on the surface of the ground, and underground."},{"code":1195,"name":"tsunamis","parent":822,"scope":"Sea waves generated by submarine earthquakes, volcanic eruptions, or landslides, which are generally imperceptible in deep water but may be very destructive when striking the shoreline."}]}