THE CHRONO-CONTINUUM - AN APPROACH TO MODELING PEDOGENESIS IN MARSH SOILS ALONG TRANSGRESSIVE COASTLINES

More than a half century ago, time was popularized as one of the state factors of soil formation, The accompanying concept of the ''chronose quence'' significantly impacted research efforts to understand the rol e of time in soil genesis. Two difficulties have plagued chronosequenc e soils studies: (i) small data sets (limited by what is available in nature), and (ii) variability within the data sets (introduced by geog raphical variations in other soil-forming factors),This paper describe s a theoretical approach to developing more accurate chronofunctions i n transgressive estuarine pedogenetic systems by minimizing these obst acles; it is here called the chrono-continuum. The encroachment of the sea on upland soils during the most recent coastal transgression caus ed a dramatic shift in pedogenetic processes, which brought about a nu mber of significant changes in physical, chemical, mineralogical, and biological soil properties, The slowly rising sea level (a few mm/yr) has permitted the establishment of tidal marsh vegetation, The subsequ ent vertical accretionary growth of marsh vegetation generally has kep t pace with sea-level rise,The rate of sea-level rise during an interv al of marsh soil formation can be determined by various dating techniq ues, which can be related to the elevation of the submerged land surfa ce through a topographic survey, In this way it is possible to recreat e the relationship between sea level and the land surface at any point in the history of the marsh, Thus, the continuum in space (along the topographic surface) can be translated into a continuum in landscape t hat represent different points in time (addressing the first difficult y), and this can be done within a relatively small geographic distance (addressing the second difficulty).