{"thcode":2,"term":{"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."},"uf":[],"bt":[{"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."},{"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":[],"rt":[{"code":455,"name":"geologic history","parent":287,"scope":"Record (and inferred reconstruction) of the origin and development of the earth since its formation."},{"code":1681,"name":"tephrochronology","parent":1680,"scope":"Age determination of rocks and deposits by correlation of volcanic ash layers (tephra) that bound the deposits below and above."}]}