GEOARCHAEOLOGICAL SIMULATION OF MEANDERING RIVER DEPOSITS

Fluvial processes have the potential to obscure, expose or even destroy portions of the archaeological record. Floodplain aggradation can bury and hide archaeological features, while actively migrating channels can erode them. The archaeological record preserved in the subsurface of a fluvial system is therefore potentially fragmented and three-dimensionally complex, especially when the system was subjected to successive phases of alluviation and entrenchment. Here, we present a simulation model that is used to gain insight into the 3D subsurface distribution, visibility and preservation potential of the archaeological record in a meander-floodplain system, as a function of geomorphic history. Simulation results indicate that fluvial cut-fill cycles can strongly influence the density of archaeological material in the subsurface. Because of this, interpretation of floodplain habitation based solely upon features visible in the shallow subsurface, through traditional archaeological techniques such as aerial photography and geophysical prospection, can be misleading. In the examples shown, the loss of archaeological record by channel migration is ranges between 45-90% over 12,000 years for channel belt dominated systems, decreasing exponentially to 10-30% for rivers where the floodplain width is a multiple of channel belt width. The modeling procedure presented can be used to test excavation strategies in relation to hypothesized scenarios of stratigraphic evolution for archaeological sites.