{"thcode":4,"term":{"code":"0","name":"Earth material","parent":null,"scope":"Geologic map unit classification (Bruce R. Johnson) version 6.2: A hierarchical classification of earth materials for digital geologic maps."},"uf":[],"bt":[],"nt":[{"code":"5","name":"Metamorphic rock","parent":"0","scope":"A rock derived from pre-existing rocks by mineralogical, chemical, and\/or structural changes, essentially in the solid state, in response to marked changes in temperature, pressure, shearing stress, and chemical environment, generally at depth in the earth's crust."},{"code":"4","name":"Plutonic rock","parent":"0","scope":"A rock formed at considerable depth by crystallization of magma and\/or by chemical alteration.  It is characteristically medium- to coarse-grained, of granitoid texture."},{"code":"2","name":"Sedimentary rock","parent":"0","scope":"A rock resulting from the consolidation of loose sediment that has accumulated in layers..."},{"code":"6","name":"Tectonite","parent":"0","scope":"A rock whose fabric reflects the history of its deformation."},{"code":"1","name":"Unconsolidated material","parent":"0","scope":"A sediment that is loosely arranged or unstratified, or whose particles are not cemented together, found either at the surface or at depth."},{"code":"3","name":"Volcanic rock","parent":"0","scope":"A generally finely crystalline or glassy igneous rock resulting from volcanic action at or near the Earth's surface, either ejected explosively or extruded as a lava.  The term includes near-surface intrusions that form a part of the volcanic structure."}],"rt":[]}