A survey has been made of some low-lying porphyritic igneous rock masses which occur about 11 miles north-northeast of Kingston, adjacent to the Princes Highway near the southern end of the Coorong, for the purpose of quantifying possible reserves of construction materials which might be applied to railway and/or port building projects planned for the district. Outcropping reserves of granodiorite within the main, solely viable exposed mass are estimated to be 108,700 tons, while an additional 93,300 tons of potential reserves have been calculated to a depth of 5 feet below ground level. Quarrying of the latter would involve the removal of 11,000 cubic yards of overburden, and would necessitate the control and removal of groundwater, due to the essentially constant waterlogged nature of the surrounding country.