It extended from Muchea and Yanchep in the south to Mogumber and Ledge Point in the north. The county approximately corresponds to the northern part of the Swan Land District and the north-western part of the Avon Land District, which form the basis for land titles in the area.
References
^Crowley, F.K. (1963). "Stirling, Sir James (1791–1865)". Australian Dictionary of Biography. Melbourne: Melbourne University Press. Retrieved 25 January 2016.