The rich rock art of Australia, especially of Arnhem Land and the Kimberly continues to be the subject of research, as well as fierce debate about their meaning and age, with obvious implications for Aboriginal cultural history. Three signficant styles are identified : the 'Bradshaws', (named after explorer Joseph Bradshaw who discovered them in the 1800s) the 'Dynamic' and the 'Wanjina' paintings. Most of the more than 100,000 ancient sites are not effectively protected but are of great importance to living Aboriginal people.