These notes provide detailed unit descriptions and a synthesis of the geology of the Moss Vale 1:100 000 geological map sheet area, which lies about 120 km southwest of Sydney and covers parts of the eastern Lachlan Orogen and the overlying southern Sydney Basin. In the area, the oldest rocks of the Lachlan Orogen are strongly deformed, regionally metamorphosed Ordovician deep marine sedimentary rocks. In the west, they are overlain by latest Silurian to Early Devonian, mostly shallow marine, sedimentary and volcanic rocks. A Late Devonian sequence of sedimentary and volcanic rock is preserved in the Budawang Syncline. The orogen contains many Early Devonian and Carboniferous plutons. The Lachlan Orogen rocks are unconformably overlain and largely obscured by the Permo-Triassic sedimentary sequence of the Sydney Basin over much of the map area. This little-deformed sequence dips gently to the north and northeast. Local Cenozoic deposits include basic volcanic rocks, alluvial gravels, soils and alluvium.
Trigg S.J. & Campbell L.M. 2016. Moss Vale 1:100 000 geological sheet 8928. Explanatory Notes. Geological Survey of New South Wales, Maitland, NSW.
Mapping during 2008 and 2009 was supplemented by a detailed review and compilation of previous work. Surface mapping and drillhole data were used to interpret the subsurface extents of the Lachlan Orogen basement and individual units of the Sydney Basin. New SHRIMP zircon U-Pb isotopic ages of various plutons and volcanic rocks were obtained. Some stratigraphic names were modified during the project.