A comparative analysis of obsolescence patterns of the U.S. Geoscience literature

The United States (U.S.) geoscience literature is employed as a vehicle to study the phenomenon of obsolescence. Problems investigated include the classical and ephemeral aspects of subject literatures, diversity among narrowly defined literatures within broadly defined subject literatures, and the effect of literature growth on obsolescence. Comparisons are made: 1. among time‐frequency bibliographs based on citation counts from each of twelve major journals published in 1969; 2. between bibliographs of three major journals for the years 1969 and 1949; and 3. between uncorrected and corrected obsolescence curves. Each journal yields citation patterns comprised of both an ephemeral and a classical literature component. Within this framework apparent obsolescence varies across a broad spectrum, from physics/chemistry‐oriented geoscience subdisciplines with relatively short “half‐lives,” to those biology‐oriented with relatively long “half‐lives.” Obsolescence rates of traditional geoscience fields seem to vary little between 1949 and 1969 in contrast to those of fast‐changing fields such as solid earth geophysics. The relationship between obsolescence curves uncorrected and corrected for growth suggests the operation of factors that control research fronts. The effect of literature size on obsolescence, though minor for the recent literature, is more pronounced for the classical literature.