GEOSCIENCE TERMINOLOGY DEVELOPMENT FOR THE NATIONAL GEOLOGIC MAP DATABASE

One of the principal technical challenges facing designers of the National Geologic Map Database is the variability in the usage of terminology describing geologic phenomena and interpretations. Much geologic data based on field observation is terminological, but the usage of individual words evolves with time, and varies regionally. Integration of geoscience information from different sources requires a formalized terminology. Information system engineering demands a completely formal system, but geologists are very resistant to requirements to conform to a formal vocabulary. In order to accommodate both approaches the NGMDB is developing a standard terminology (‘science language’) with definitions, and a procedure for defining alternate terminology systems. The standard terminology includes 4 components—a definition of scope, the list of terms, a schema specifying how descriptions of the terms are constructed, and definitions for the terms. Initially, definitions are constructed as text; the goal is to convert the text descriptions to a formalized syntax (e.g. DAML-Oil, OWL) to allow computerized inference. In order to be considered as part of the NGMDB, alternate terminology systems will need to include all four components, along with a link from each term in the alternate terminology to the most specific subsuming term in the standard terminology. Resolution of queries in a distributed information system using multiple terminology systems will require non-relational inference capabilities based on Description Logic and concept similarity metrics from case-based reasoning systems. Our current focus is on developing a standard terminology by compiling terms from existing geologic map database systems, and developing unambiguous, non-overlapping text definitions for the terms. Structure of the terminology is designed to fit into evolving North American Geologic map information conceptual model (NADM-NORTON) and science language. Major topics in the terminology include classifications for rocks, non-consolidated materials, geologic structure, genetic environments, geologic processes, and vocabularies for describing rocks and geologic units.