The Wianamatta Group has been divided into two sub-groups—the Liverpool sub-group (lower, approximately 400 feet thick, predominantly shale lithology) and the Camden sub-group (upper, approximately 350 feet thick, sandstone lithology prominent with shale). The Liverpool sub-group includes three formations (Ashfield Shale, Minchinbury Sandstone, Bringelly Shale). The Camden sub-group includes five formations (Potts Hill Sandstone, Annan Shale, Razorback Sandstone, Picton Formation, Prudhoe Shale).
The sedimentary petrology of the graywacke-type sandstones and the relation of the lithology to the sedimentary environment and tectonics is discussed. A new element, the envirotope, is defined to be used with the elements lithotope and tectotope (Krumbein and Sloss, 1951) to describe a lithologic sequence.
Post-depositional tectonics are briefly discussed and a new series of tectonic features described from the southwestern suburbs of Sydney.