Geology of the Maydena Range

The oldest rocks of the area are the (?) Precambrian pyritic quartzites with interbedded conglometates.
These are overlain by 60 m of pebbly siltstone, about 300 m of ferruginous sandstones and siltstone and 300 m of quartzitc and siltstone which represent a stable tectonic environment of pre-Ordovician age. The pre-Ordovician rocks were folded before deposition of the Ordovician sediments.
The Arenigian Florentine Valley Mudstone is at least 140 m thick and is overlain by the lower 600m. of the Gordon Limestone, the upper parts of. Which are faulted out.The Lower•Upper Middle Devonian .Tabberabberan Orogeny resulted In the formation of north-westerly plunging folds.
A complete flatly dipping Permian sequence begins with at least 220 m of Lower Sakmarian Wynyard Tillite, which was derived from a glacier With a north-westerly origin .This. is overlain by 137 m of Woody Island Siltstone, 9.2 m of fossiliferous siltstones, 3.7 m of Darlington Limestone, and 32 m of Bundella Mudstone all of which are marine. These are overlain by the freshwater sedimennts of the Mersey Group (with a maximum thickness of 52 m), followed] by a marine sequence composed of 80 m of the Cascades Group, 64 m of the Malbina Siltstone and Sandstone and about 150 m of the Ferntree Group. The terrestrial Cygnet Coal Measures 4.4 m thick, is the top Permian formation. The Permian rocks form a very shallow east plunging syncline.
Three hundred and twenty metres of freshwater Triassic sediments disconformably overly the Permian rocks and are intruded by a Middle Jurassic dolerite sill. Normal faults, with down throw to the east -north-east and to t he northwest and probably associated with the formation of the Tertiary Derwent Graben, cut the older rocks. Dolerite talus slopes developed as periglacial material during the Pleistocene.