Bulgo Sandstone

Bulgo Sandstone is a sedimentary rock occurring in the Sydney Basin in eastern Australia. This stratum is up to 100 metres thick, formed in the early Triassic (Olenekian). A component of the Narrabeen Group of sedimentary rocks. It consists of layers of fine to medium-grained quartz-lithic sandstone, with lenticular shale interbeds.

TypeGeological formation

Unit ofNarrabeen Group

UnderliesBald Hill Claystone

Thicknessup to 100 metres (330 ft)

Quick facts Type, Unit of ...

Bulgo Sandstone
Stratigraphic range: Olenekian PreꞒ Ꞓ O S D C P T J K Pg N ↓
Outcrop of the Bulgo Sandstone at Long Reef in New South Wales
Type	Geological formation
Unit of	Narrabeen Group
Underlies	Bald Hill Claystone
Thickness	up to 100 metres (330 ft)
Location
Location	Sydney Basin
Country	Australia
Extent	Sydney

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Often seen as a grey-green colour when exposed, the Bulgo sandstone contains a high level of particles of volcanic rocks, and is dissimilar to other Sydney sandstones, such as Hawkesbury sandstone and Newport Formation. The rock breaks down to create a relatively fertile clayey soil. These soils contribute to the rainforest growth in the northern Illawarra. Bulgo sandstone may be seen at the "figure eight" rock pool at Royal National Park and at Long Reef in the northern Beaches in Sydney. A fossil of the giant amphibian Bulgosuchus gargantua was found at Long Reef.^[1][2][3]