The taphonomy of human footprints in an estuarine setting: implications for quaternary track-sites in intertidal zones

The purpose of this paper is to understand the preservation of human footprints formed in estuarine settings, with a specific focus on survival time and morphological modification. To this end, we conducted a taphonomic study by creating five trackways at two different sites on the intertidal mudflats of a modern estuary in North Wales. Trackways were monitored across multiple tidal cycles using photogrammetry to create timelapsed orthomosaics and digital elevation models. Our results exhibit a pattern of morphological footprint decay for individual tracks, while showing persistence at the same time. Under progressive influence of the tides, anatomical detail decreases, push-up ridges erode, and footprint outlines become wider with eventual sediment infill. Despite this, individual tracks remain identifiable and biometric inferences (e.g., foot length) are consistent throughout, with intra-trackway variability comparable to changes observed over time. Estimates for a complete removal of the tracks at the study sites are after five to seven days (10–14 tidal cycles). This will vary between sites as with variations in sediment properties, local hydrodynamics, and track orientation. We suggest that tidal duration is critical for footprint preservation and stress that taphonomic processes are different at sites with aeolian sediment formation. While site-specific, our results offer broader insights into the formation and survival of Quaternary footprints in dynamic coastal environments.