The pressure record underfoot: Using ground penetrating radar to obtain pressure patterns of buried footprints

• Ground penetrating radar can image buried footprints in soft sediment. • Results show primarily a record of undertrack pressure rather than morphology. • Detailed study of ichnofossils using radar requires relatively high frequencies. Fossilised trackways are a key source of evidence for reconstructing how ancient humans and animals moved across the landscape. The morphology of tracks is of particular importance because it allows inferences to be made about plantar pressure and therefore mechanics of motion of the track maker. However, the typical methods of excavation and photogrammetry used to document these tracks can be time consuming and may not be ideal at sensitive sites. This paper explores the use of ground penetrating radar to record the morphology of human tracks buried in soft sediment at White Sands National Park, New Mexico. The results demonstrate that a record of plantar pressure is preserved in the radar data and that this record might be a more direct measure of pressure than the typical proxy of footprint depth. This suggests that ground penetrating radar is a strong choice of method in ichnological studies.