Mulbring Quarry

Mulbring Quarry is a well known fossil site located in the Hunter Valley near the town of Mulbring. The quarry contains an overabundance of marine fossils including bryozoans, bivalves, crinoids and brachiopods. There are fossils everywhere, in every rock that you pick up. The site is dominated by the bryozoan Fenestella which can be identified in pretty much every rock sampled. Other fossils known to have been found at Mulbring Quarry which occur less commonly include corals, forams, gastropods, starfish and rarely, trilobites. The lithology of the rocks is mostly siltstone and the modes of preservation of the fossils are casts and moulds. 

 A beautiful specimen unfortunately too big for me to take.

The palaeoenvironment and conditions of deposition at Mulbring Quarry have been the subject of academic research. Vanderlaan (2007) concluded that the deposition of the specimens took place in a quiet shallow marine, low energy environment. This is evidenced by low levels of fragmentation in the bryozoans and most of the bivalves and brachiopods are articulated meaning that the segments are found still attached together. The position of the site on the continent can also be inferred by the high levels of lithic material and the presence of wood fragments (Vanderlaan, 2007) indicating that the original site of deposition was mid-continental shelf below the normal wave base and at a high latitude.  Vanderlaan (2007) notes that the presence of drop stones is an indicator of a cold water environment with seasonal ice cover. The drop stones and wood fragments however are quite small and are not common but still occur.

References

Excursion Handout. 2012. Permian Fossils and Palaeoenvironments of the Hunter Valley.
Percival, I.G. 1979. The geological heritage of New South Wales, volume 1. Geological Society of Australia, Sydney.
Vanderlaan, T. 2007. Middle Permian palaeoecology and depositional environment of the Fenestella Shale Member, Branxton Formation, lower Hunter Valley. Unpub. Hons Thesis, Macquarie University.