Detecting footprints with GPR

Recent field research at White Sands National Park, New Mexico, USA, has used ground-penetrating radar to detect the footprints of Pleistocene humans, mammoths, and ground sloths. The technique has been succesful with a range of antenna frequencies and for detecting footprints of many different sizes. Perhaps more importantly, the method has been shown to successfully detect fooprints that are not visible to the human eye, often with sufficent detail to differntiate species. This work raises an obvious question about whether GPR could be used to detect footprints in a range of other contexts, or whether the circumstances seen at White Sands are unique.