He has written extensively on Victorian Aboriginal history including editing the journals of
George Augustus Robinson. He worked with The
Victorian Aboriginal Corporation for Languages and in 2002 published the
Dictionary of Aboriginal Placenames of Victoria and several related regional placename publications. He was one of the organisers of the second
Trends in Toponymy conference in Ballarat in 2007, and is researching a book on Aboriginal toponymy for the
ANU E-Press series. Other important published research includes work on massacre sites in Western Victoria in the 1995 publication
Scars in the landscape : a register of massacre sites in Western Victoria 1803–1859. The interaction between the
Wurundjeri people and the early settlement of
Melbourne was told in the 2004 book –
A bend in the Yarra : a history of the Merri Creek Protectorate Station and Merri Creek Aboriginal School 1841–1851, which Clark co-authored with Toby Heydon. Clark has also written on the Aboriginal presence on the
Ballarat goldfields in the 1850s noting that while there is no evidence for any direct involvement of Aboriginal people in the events of the
Eureka Rebellion in 1854, aboriginal people may be relevant to the Eureka story through the event taking place on
Wathaurong aboriginal land. The early policing of the Goldfield was done by the
Native Police Corps, and oral history that Aboriginal people looked after some of the children of the Eureka miners after the military storming of the Eureka Stockade and subsequent massacre of miners. ==Major works==