When you consider that the home was constructed in 1858 it's not surprising that there is plenty of history to be discovered online when you search 'Terragong at Jamberoo'. Here's a sampling of the many links we've stumbled across relating to the house, the farm, the region and of course the Marks family (who owned the property for seven generations). Terragong is indeed "a unique piece of dairying history nestled in the lush green valley of Jamberoo."
Australian Heritage Database
Historic home to go under the hammer
Booth v Dairv Farmers' Co-operative. Ltd.
(From the Sydney Morning Herald, November 1, 1932)
First century of dairying in New South Wales online
Early Land Settlement in Illawarra 1804-1861
Obituary - Marks, Ernest John (1861–1925)