His studies of the Sphinx have contributed to a debate on the outer fringes of archaeology regarding the date of the monument. He suggested on the basis of weathering evidence that the Sphinix is older than its commonly accepted 4th dynastic date and instead it and two other buildings on the Giza Plaeau date to the early dynastic or late predynastic period.
Publications include A geomorphological study of the Giza necropolis with implications for the development of the site (Archaeometry 43: 1 (2001) pp149–165)
reproduced from the Journal of the Ancient Chronology Forum (JACF) 9 (2002), pp. 5–21