The Upper Triassic Bocock Formation varies from 0 to 63 metres thick between Silver Sands and Carbon creeks, having been completely eroded in the lower part of Silver Sands Creek. It consists of very resistant light-grey to grey weathering, grey to brownish grey limestone that is typically micritic to very finely crystalline, but which also has some coarse bioclastic units containing rounded crinoid and brachiopod fragments. To the north, along the west side of McNairn Creek, it becomes coarse-grained calcarenite and is slightly more silty and dolomitic than to the south. Bedding is thick to indistinguishable, and massive.

A minimum of 20 metres of limestone averaging nearly 55 per cent CaO is reported to be present from Discovery Creek to Tiger Creek, a distance of over 10 kilometres (Assessment Report 20410, Figure 2.2). The analysis of one sample taken across 21 metres is recorded as 55.1 per cent CaO, 0.1 per cent MgO, 0.9 per cent insolubles, 0.5 per cent R2O3, 43.7 per cent loss on ignition and 0 per cent SiO2 (Assessment Report 20410, Table 3.1).