Dueling over the Dead

The only thing that distinguishes Grahame Walsh's home from any other in suburban Brisbane is the eerie silhouette overlooking his letterbox. It depicts a wanjina - a mysterious ancient figure painted on cave walls in Australia's remote northwest. But the figure merely hints at what lies inside the two-story brick house: hundreds of thousands of images of some of the country's most extraordinary pieces of rock art, including the famous Bradshaw paintings, many of them unseen by non-Aborigines until Walsh trekked through hostile, lonely terrain to photograph them.

For his work in recording and interpreting the fragile art, Walsh...