Mittagong Formation

The Mittagong Formation is a sedimentary rock unit in the Sydney Basin in eastern Australia.^[1]

Mittagong Formation
Stratigraphic range: Triassic PreꞒ Ꞓ O S D C P T J K Pg N
Mount Ku-ring-gai, Australia
Type	Geological formation
Underlies	Ashfield Shale
Overlies	Hawkesbury sandstone
Thickness	up to 10 metres (30 ft)
Location
Location	Sydney Basin
Country	Australia
Type section
Region	Mittagong
Country	Australia
Thickness at type section	15 metres

Formation

Laid down in the Triassic Period, it may be seen as an interval of interbedded fine-grained sandstone and shale between the Ashfield Shale (above) and the Hawkesbury sandstone (below). The maximum thickness around Sydney may be ten metres.^[2] Near Town Hall railway station, the formation is 8 metres thick. In the type area at Mittagong it is 15 metres thick.

Whereabouts

In northern Sydney it can be seen in several areas, such as West Pymble^[3] and Mount Ku-ring-gai.^[4] This rock formation is associated with the critically endangered Sydney Turpentine-Ironbark Forest.^[5]

See also

• Narrabeen group