{"thcode":2,"term":{"code":1104,"name":"stratigraphy","parent":464,"scope":"Branch of geology concerned with the study of the formation, composition, ordering in time, and arrangement in space of stratified rocks."},"uf":[],"bt":[{"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":291,"name":"earth sciences","parent":1019,"scope":"Broad term for all science related to the study of the earth."},{"code":1019,"name":"sciences","parent":1,"scope":"Major educational fields, fields of study, and professional groupings within USGS."},{"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":115,"name":"biostratigraphy","parent":1104,"scope":"Branch of geology concerned with the separation and differentiation of rock units based on the fossils they contain."},{"code":668,"name":"lithostratigraphy","parent":1104,"scope":"Branch of stratigraphy dealing with the study of units of rock. Each unit is composed of a body of rock which is dominated by a certain lithology or similar color, mineralogic composition, and grain size."}],"rt":[{"code":84,"name":"bedrock geologic units","parent":1103,"scope":"Units of consolidated (solid) rock that underlie soils or other unconsolidated materials."},{"code":125,"name":"borehole logging","parent":375,"scope":"Method of recording the physical characteristics of the subsurface as a function of depth by observations during drilling of a well or borehole, studying the resulting core, or by lowering instruments into a drilled hole."},{"code":325,"name":"electrical resistivity logging","parent":125,"scope":"Recordings made to identify the composition of subterranean materials at different depths in a borehole by measuring their ability to resist the flow of an electric current."},{"code":424,"name":"gamma-ray logging","parent":125,"scope":"Recording of the measurements of natural gamma radiation emitted from the rocks in a borehole to study the subsurface structures."},{"code":438,"name":"geochronology","parent":464,"scope":"Study of the age of the earth by dating geological formations, rocks, and fossils."},{"code":452,"name":"geologic contacts","parent":1103,"scope":"Junctions of two different rock formations varying by type or age of rock, including faults, unconformities, and bedding planes."},{"code":455,"name":"geologic history","parent":287,"scope":"Record (and inferred reconstruction) of the origin and development of the earth since its formation."},{"code":1103,"name":"stratigraphic sections","parent":287,"scope":"Vertical arrangement in layers of rock units whose sequence is used to study the geological history of the strata."},{"code":1127,"name":"surficial geologic units","parent":1103,"scope":"Rock units on the earth's surface."},{"code":1198,"name":"unconformities","parent":452,"scope":"The contact between older rocks and younger sedimentary rocks where erosion had removed some of the older rocks before the younger rocks were deposited."}]}