By KAL
The Sydney Basin is appriximately 350 kilometres long and 100 kilometres wide.
The rock types of the basin are: Marine shales and Mudstone at the bottom, coal measures in the middle and sandstone at the top.
The sandstone is devided into three groups:
1.Narrabeen Group(bottom)
2.Hawksbury Sandstone(middle)
3.Wianamatta Group(top)
The Wianamatta group is made up of shale while the other two are sandstone types that were formed by erosion of the Sydney Basin.
The Sydney Basin is also made of a succesionof Permian and Triassic marine and non-marine, cold-climate, clastic sedimentry rocks, together with a series of intrusions and intrusions wich wereemplaced during several magmatic episodes.
The Formation of the Sydney Basin in the Late Palaeozoic was caused by a multistage process of cratonic accretion in the Lachlan Fold Belt, followed by subsidence as part of a foredeep basin. A Mid-Permian period of diastrophism produced the New England Fold Belt and the final stucture of the Sydney Basin.
