Ashfield Shale
Ashfield Shale | |
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Stratigraphic range: | |
Wiannamatta group | |
Sub-units | Kellyville Laminite Member, Mulgoa Laminite Member, Regentville Siltstone Member, Rouse Hill Siltstone Member |
Overlies | Mittagong Formation |
Thickness | up to 64 metres (210 ft) |
Lithology | |
Primary | Shale |
Location | |
Location | Sydney Basin |
Country | Australia |
Type section | |
Named for | Ashfield |
Ashfield Shale is part of the
Description
Ashfield Shale comprises black
Small scale bedding is abundant. The shales are sandy at the top of the sequence. There are up to ten bands in a fifteen-metre section. The fine grained silty sediments were laid down in a low energy, south-east flowing deltaic setting, near the shores of a shallow sea. Ashfield Shale underlies the Prospect dolerite intrusion in Pemulwuy.
Natural selection in which the Ashfield Shale is completely exposed is rare. However, it can be seen at railway and roadside cuttings, as well as old quarries. With weathering and exposure, the shale becomes a paler colour.
Weathering of the shale units produces a reddish/brown
Engineering and construction
The adjacent Hawkesbury Sandstone is considered a safer bedrock than the (less stable and
Flora
Ashfield Shale is associated with the
Industry and agriculture
In the earlier days of Sydney, the Ashfield Shale supported a number of quarries. The shale provided a suitable raw material for brickmaking.[6] Sydney soils based on shale are not particularly fertile. But at Parramatta they proved more suitable to agriculture than those at Farm Cove, in the early days of the First Fleet.
Fossils
Ashfield Shale is considered a freshwater
Fossils are not common in this stratum, however, fossil
The Ashfield Shale has also yielded a shark species, a lungfish species, six species of paleoniscid fish, a species of holostean fish, and a subholostean fish.[8]
Fossil fauna
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Bivalvia of the Ashfield Shale | ||||
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Sharks of the Ashfield Shale
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Fish of the Ashfield Shale | ||||
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Amphibians of the Ashfield Shale
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Reptiles of the Ashfield Shale
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References
- ^ a b c d Packham, Gordon Howard, ed. (November 1969). The Geology of New South Wales. Sydney: Geological Society of Australia. pp. 417β421.
- ^ "Geological History". Sydney Olympic Park Authority. NSW Government. Retrieved 23 July 2012.
- ISBN 0-7318-1031-7.
- ^ "Lane Cove Collapse". Tunnel Talk. Retrieved July 22, 2012.
- ^ "Recent Experiences in Grouting Sydney Sandstone". Australian Tunnelling Society. ats.org.au. Retrieved July 23, 2012.
- ^ a b John Johnson (2008). "Croydon". Dictionary of Sydney. Dictionary of Sydney Trust. Retrieved 23 July 2012.
- ^ "Blue Gum High Forest - Typical Form" (PDF). Mapping and Assessment of Key Vegetation Communities Across the Ku-ring-gai Local Government Area. Ku-Ring-Gai Council. Archived from the original (PDF) on 18 March 2011. Retrieved 23 July 2012.
- ^ Cosgriff, J. W. (1973). "Notobrachyops picketti, a brachyopid from the Ashfield Shale, Wiannamatta Group, New South Wales". Journal of Paleontology. 47 (6): 1094β1101.