{"thcode":2,"term":{"code":725,"name":"metamorphic rocks","parent":1005,"scope":"Sedimentary or igneous rocks which have undergone such intense changes in temperature, pressure, structural stress, or chemical environment that they are transformed into denser rocks."},"uf":[],"bt":[{"code":1005,"name":"rocks and deposits","parent":287,"scope":"Solid masses that make up the earth's crust as well as accumulations of materials. Use for major rock types and unconsolidated deposits. For deposits of economic value, see related terms."},{"code":287,"name":"earth characteristics","parent":1174,"scope":"The measurable, definable properties and features of the earth."},{"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":[],"rt":[{"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":883,"name":"petrology","parent":464,"scope":"Branch of earth sciences concerned with the origin, structure, alteration, and composition of rocks."}]}