THE GUNS WERE the first to catch my eye. One, two, three of them, looming larger than life on the rock wall. One sits above a figure in white kaolin clay, hands on waist, pipe in mouth, broad-brimmed hat: the familiar whitefella stance. Amidst the array of Dreaming creatures, these signs of contact are stark.

I look up at this fresco from the pit below. A large crocodile returns my gaze. He has been eyeing me off for seven weeks now, watching quietly as we excavate around him. I am in Kakadu National Park, on the fringes of Arnhem Land, standing at the bottom of the oldest archaeological site in Australia.