Bombo Headland Quarry Geological Site
| Bombo Headland Quarry Geological Site | |
|---|---|
 | |
| Location | Princes Highway, Bombo, Municipality of Kiama, New South Wales, Australia |
| Coordinates | 34°39′00″S 150°51′48″E / 34.6499919°S 150.8633683°E |
| Owner | Department of Planning and Infrastructure; Sydney Water |
| Official name | Bombo Headland Quarry Geological Site; Bombo Quarry |
| Type | state heritage (landscape) |
| Designated | 2 April 1999 |
| Reference no. | 177 |
| Type | Geological site or area |
| Category | Landscape – Natural |
  Location of Bombo Headland Quarry Geological Site in New South Wales | |
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Bombo Headland Quarry Geological Site is a heritage-listed former quarry and now geological site at Princes Highway, Bombo, Municipality of Kiama, New South Wales, Australia. It is also known as Bombo Quarry. It was added to the New South Wales State Heritage Register on 2 April 1999.[1]
History
In 1979 a nomination was received from the Geological Society of Australia (NSW Division) for the Bombo Quarry. The importance of the geological features was brought to the Heritage Council's attention by Dr. Suzanne Wass of Macquarie University's School of Earth Sciences. The quarry was owned by the Metropolitan Water, Sewerage, and Drainage Board and it was proposed that a pollution control plant be constructed on the floor of the disused quarry.[1] It also made an appearance in Mighty Morphin Power Rangers: The Movie as part of the planet Phaedos.[2]
Following site inspections and lengthy consultations between the Metropolitan Water, Sewerage and Drainage Board, NSW Heritage Council, NSW Planning Commission, and other key agencies a Permanent Conservation Order was placed over the site in 1983. It was transferred onto the State Heritage Register in 1999.[1]
Description
Two units of the Late Permian Gerringong volcanic facies are exposed on Bombo Headland. The Kiama Sandstone member forms a narrow wave-cut platform and adjacent vertical cliff face around the south-eastern extremity of the quarry. To the north, the
Petrographic descriptions of the latite emphasise its conspicuous porphyritic texture; large labradorite to andesine phenocrysts with minor clinopyroxene are set in a groundmass of feldspar microlites with interstitial chlorite and iron oxide. The latter is commonly vesicular. Agglomerates or volcanic breccias are developed in some areas of the quarry. E.g. in the south-western portion near the access road. This lithology is readily distinguished from the latter by its chaotic appearance and light-coloured matrix.[1]
A capping of cream-coloured weathered latite, still retaining the characteristic porphyritic texture, maybe studied at the top of the northern and western quarry faces. This sharply-defined zone of surface weathering and soil formation overlies relatively fresh rock exhibiting columnar jointing.[1]
The Bombo Latite Member was subsequently intruded by at least five basaltic (Monchique) dykes of probable Tertiary age which flowed around and between the columns of latite often taking 90-degree changes in direction. Early workers[3] mapped and described these dykes, but subsequent quarry development provided further exposures and obliterated others. Today dykes are mainly in the northern half of the quarry, but at least one extends across the excavation floor in the isolated columnar stacks. They are of interest due to their inclusions of xenoliths and xenocrysts, which are believed to represent fragments of the earth's mantle incorporated in magmas originating from within that zone. Sussmilch (1905) described xenoliths of hypersthene gabbro, augite peridotite, enstatite peridotite and pyroxenite occurring as rounded fragments and boulders embedded in the monchiquite. From a deeper level of what was probably the same dyke, Wilshire & Binns (1961) recorded hornblendite and glimmerite as the dominant xenoliths. Present exposures of most of the other dykes appear to lack macroscopically visible xenoliths.[1]
Heritage listing
Bombo Headland Quarry Geological site is of research/technical significance in the numerous dykes which cut the Permian Bombo Latite. One of the dykes is geologically unique and contains abundant xenoliths which represent material brought up to the Earth's mantle, about 80 kilometres below the surface of Eastern Australia. The mineral assemblages including
Bombo Headland Quarry Geological Site was listed on the New South Wales State Heritage Register on 2 April 1999.[1]
See also
References
Bibliography
- "Bombo Headland Quarry Geological Site". 2007.[permanent dead link]
- Attraction Homepage (2007). "Bombo Headland Quarry Geological Site".
Attribution
This Wikipedia article was originally based on Bombo Headland Quarry Geological Site, entry number 00177 in the New South Wales State Heritage Register published by the State of New South Wales (Department of Planning and Environment) 2018 under CC-BY 4.0 licence, accessed on 1 June 2018.
External links
Media related to Bombo Quarry at Wikimedia Commons