Basalts and silcretes on the coast near Ulladulla, southern New South Wales

Young, R. W.; McDougall, Ian

doi:10.1080/00167618208729224

Cited by 55 publications

(47 citation statements)

References 11 publications

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“…Compared with the East Victoria Highlands, the adjacent New South Wales alps and tablelands are considered to have been tectonically stable throughout most of the Cenozoic: Young (1977, Young & McDougall (1982, Bishop et al (1985), Bishop (1986), Taylor et al (1985, 1990 and Nott et al (1991) all postulated a mostly Mesozoic age for uplift. Others considered some uplift to be in response to Cenozoicaged denudational isostatic rebound (Bishop & Brown 1992), and Ollier & Taylor (1988) interpreted significant (up to 1 km) post-Oligocene uplift.…”

Section: Proposed Uplift Mechanismsmentioning

confidence: 99%

No mountains to snow on: major post-Eocene uplift of the East Victoria Highlands; evidence from Cenozoic deposits

Holdgate

Wallace

Gallagher

et al. 2008

Australian Journal of Earth Sciences

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Section: Proposed Uplift Mechanismsmentioning

confidence: 99%

No mountains to snow on: major post-Eocene uplift of the East Victoria Highlands; evidence from Cenozoic deposits

Holdgate

Wallace

Gallagher

et al. 2008

Australian Journal of Earth Sciences

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“…Yet these estimates seem reasonable given the very slow rates of long-term denudation determined from the excellent K-Ar chronology for the widespread basalts in this region (Wellman & McDougall 1974;Young & McDougall 1982;1985). Basalts, dated at 27 to 30 Ma, overlying fluvial sediments near sea level south of Nowra (Figure 1), demonstrate the great age of the coastal lowland and indicate a maximum possible rate of 170 m/Ma for the recession of the coastal escarpment (Young 1983b;Young & McDougall 1983).…”

Section: Rate Of Deformationmentioning

confidence: 94%

“…The general northeast dip, at about 1°, of these Permian rocks is essentially syndepositional (Young 1977) and has been modified only slightly by two sets of low amplitude folds, one striking approximately eastnorth-east and the other north-west. Basalts of Eocene to Oligocene age (Wellman & McDougall 1974;Young & McDougall 1982;1985), together with laterite weathering profiles (Young 1977) and siliceous skins developed on the sandstone (Watchman 1993), provide chronological constraints for estimating rates of denudation and block gliding in the region.…”

Section: Regional Settingmentioning

confidence: 99%

Block gliding and rheological deformation in the Southern Sydney basin

Wray¹,

White²,

Hoskins³

1995

Australian Geographer

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Block gliding caused by low frictional resistance or by the deformation of plastic substrates has been well documented from many parts of the world, but neither of these mechanisms explains the widespread gliding of sandstone blocks away from cliffs in the southern Sydney Basin of south-eastern Australia. The movement of large blocks over declivities from near zero to a maximum of 5°, high frictional resistance and lack of high porewater pressures rule out a simple sliding mechanism and it is unlikely that slender towers of sandstone could have survived seismic vibration sufficient to overcome frictional resistance to gliding. Highly preferential dip control of the direction of gliding and of the development of benches over which the blocks move, together with mounds, similar to pressure ridges, on the benches, indicate that the block gliding is due to the rheological deformation of the underlying rock, even though it is a sandy siltstone lacking readily deformable beds. Estimated rates of deformation are only 11 m/Ma to 270 m/Ma, but are commensurate with the rates of erosional retreat of clifflines estimated from K-Ar and 14 C chronologies. This phenomenon may be a significant feature of many slowly eroding landscapes, and prompts revision of models of long-term geomorphological evolution.

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“…1). These determinations, together with studies of the deep weathering and of the dissection of the landscape, provide an exceptionally detailed Cainozoic history (Craft 1932;Wellman & McDougall 1974;Young 1977;Ruxton & Taylor 1982;Young & McDougall 1982). However, because of the difficulty of obtaining fresh basalt outcrop at Sassafras in the south-eastern part of the catchment, an important gap remained in the regional chronology.…”

Section: Introductionmentioning

confidence: 97%

The age, extent and geomorphological significance of the Sassafras basalt, south‐eastern New South Wales

Young

McDougall

1985

Australian Journal of Earth Sciences

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Basalt at Sassafras was erupted in the Middle Eocene. The K-Ar ages average 45.3 ± 4.9 Ma on whole rock and 48.4 ± 1.9 Ma on plagioclase. The basalt is not limited to a plateau capping, but extends 150 m down into adjacent valleys. Comparison with nearby Eocene basalts shows that there was in excess of 250 m of local relief in the central Shoalhaven valley by the Early Tertiary. The basalts were extruded at high elevation, and denudation of the coastal margin of the upland was already well advanced. Post-basaltic denudation has been very slow, and the Early Tertiary landscape is well preserved.

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Basalts and silcretes on the coast near Ulladulla, southern New South Wales

Cited by 55 publications

References 11 publications

No mountains to snow on: major post-Eocene uplift of the East Victoria Highlands; evidence from Cenozoic deposits

No mountains to snow on: major post-Eocene uplift of the East Victoria Highlands; evidence from Cenozoic deposits

Block gliding and rheological deformation in the Southern Sydney basin

The age, extent and geomorphological significance of the Sassafras basalt, south‐eastern New South Wales

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