Karst evolution of the Nullarbor Plain, Australia

Webb, John A.; James, Julia M.

doi:10.1130/2006.2404(07)

Cited by 39 publications

(68 citation statements)

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“…The Nullarbor Plain is outstandingly important on a national (and probably world) scale, and this is reflected in its high score (Table ). One of the largest single karst areas in the world, it is Australia's most extensive karst landscape (Lowry and Jennings, ; Webb and James, ). Although arid karst is poorly researched on a world scale (Webb and White, ), and in arid Australia, karst research is limited by the remote and unforgiving terrain, the Nullarbor is currently the research focus of several groups.…”

Section: Examplesmentioning

confidence: 99%

“…Goede et al ., ; Prideaux and Warburton, ; Blyth et al ., ; Burnett et al ., ). The Nullarbor Plain is notable for its aridity and the sparsity of its vegetation (Webb and James, ); its aesthetic qualities are iconic. It possesses a unique combination of surface, underground, and coastal features, and is an outstanding example of solutional landforms modified by increasing aridity (Webb and White, ).…”

Section: Examplesmentioning

confidence: 99%

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EarthSciencesComparativeMatrix: A Comparative Method for Geoheritage Assessment

White

Wakelin-King

2014

Geographical Research

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Geological heritage is insufficiently recognised in Australia; it should be considered in its own right, not as an addendum to other heritage values. The lack of a suitable robust and repeatable methodology has seriously constrained the assessment of geological sites suitable for the National Heritage List (NHL). A desktop assessment of Australian desert landscapes required intrinsic natural values of a diverse group of sites, spread over a vast area, to be assessed against NHL criteria. The Earth Sciences Comparative Matrix (ESCoM) was developed for this study. In the ESCoM, sites are grouped in process themes. Each is assessed against NHL criteria then compared with other similar places, according to degree of unusualness, integrity, and authenticity. A site scoring well across multiple themes has increased heritage significance. The overall values of a site are quantified, leading to a qualitative judgement on whether it achieves the threshold of outstanding heritage value. Examples of assessment using this method are given. In this methodology, significance determination is based on rigorous comparisons of specific values. It is semi‐quantitative, repeatable, and robust. It differs from other geoheritage assessment methods in its combination of process‐based groupings (facilitating the separation of site type from heritage criteria), matrix structure (minimising complexities of scale or diversity), and use of numerical rankings as an aid in decision‐making. While the study for which ESCoM was developed was focused on landforms, it can be used for other types of geoheritage (e.g. fossils, tectonic processes), with modification of matrix theme headings.

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Section: Examplesmentioning

confidence: 99%

Section: Examplesmentioning

confidence: 99%

EarthSciencesComparativeMatrix: A Comparative Method for Geoheritage Assessment

White

Wakelin-King

2014

Geographical Research

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“…This provides a suitable contrast to the fossiliferous limestone of the Nullarbor Plain, which predominantly contains calcite [CaCO 3 ] and quartz [SiO 2 ] (Webb and James, 2006). In this study, 16S rRNA gene analysis was used to assess which of the microorganisms that have adapted to soils over the Nullarbor limestone can colonize chondrites.…”

Section: Introductionmentioning

confidence: 99%

Microbial Populations of Stony Meteorites: Substrate Controls on First Colonizers

et al. 2017

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Finding fresh, sterilized rocks provides ecologists with a clean slate to test ideas about first colonization and the evolution of soils de novo. Lava has been used previously in first colonizer studies due to the sterilizing heat required for its formation. However, fresh lava typically falls upon older volcanic successions of similar chemistry and modal mineral abundance. Given enough time, this results in the development of similar microbial communities in the newly erupted lava due to a lack of contrast between the new and old substrates. Meteorites, which are sterile when they fall to Earth, provide such contrast because their reduced and mafic chemistry commonly differs to the surfaces on which they land; thus allowing investigation of how community membership and structure respond to this new substrate over time. We conducted 16S rRNA gene analysis on meteorites and soil from the Nullarbor Plain, Australia. We found that the meteorites have low species richness and evenness compared to soil sampled from directly beneath each meteorite. Despite the meteorites being found kilometers apart, the community structure of each meteorite bore more similarity to those of other meteorites (of similar composition) than to the community structure of the soil on which it resided. Meteorites were dominated by sequences that affiliated with the Actinobacteria with the major Operational Taxonomic Unit (OTU) classified as Rubrobacter radiotolerans. Proteobacteria and Bacteroidetes were the next most abundant phyla. The soils were also dominated by Actinobacteria but to a lesser extent than the meteorites. We also found OTUs affiliated with iron/sulfur cycling organisms Geobacter spp. and Desulfovibrio spp. This is an important finding as meteorites contain abundant metal and sulfur for use as energy sources. These ecological findings demonstrate that the structure of the microbial community in these meteorites is controlled by the substrate, and will not reach homeostasis with the Nullarbor community, even after ca. 35,000 years. Our findings show that meteorites provide a unique, sterile substrate with which to test ideas relating to first-colonizers. Although meteorites are colonized by microorganisms, the microbial population is unlikely to match the community of the surrounding soil on which they fall.

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“…Blowholes can exhibit very strong reversing draughts in response to changes in atmospheric pressure. Little is known about the origin and distribution of these blowholes, but they are thought to be common on the plain, possibly numbering in the order of 10 5 , in some cases acting as surface drains after occasional heavy rains until they become blocked by sediment (Lowry and Jennings, ; Webb and James, ). They have been speculated to originate from downward dissolution along root holes (Webb et al ., ) or from upward doming of underlying cavities by salt wedging (Lowry, ).…”

Section: Introductionmentioning

confidence: 99%

Origin and karst geomorphological significance of the enigmatic Australian Nullarbor Plain ‘blowholes’

Doerr

Davies

Lewis³

et al. 2011

Earth Surf Processes Landf

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The Australian Nullarbor Plain, one of the world's largest limestone platforms (~200 000 km2), has few distinctive surface karst features for its size, but is known for its enigmatic ‘blowholes’, which can display strong barometric draughts. Thousands of these vertical tubes with decimetre–metre (dm–m) scale diameter puncture the largely featureless terrain. The cause and distribution of these has remained unclear, but they have been thought to originate from downward dissolution and/or salt weathering. To elucidate blowhole distribution and mode of formation we (i) correlated existing location data with Shuttle Radar Topography Mission (SRTM) data, which distinguishes the subtle undulations (< 10 m per km) of the landscape, (ii) surveyed blowhole morphology and (iii) determined their rock surface hardness. Over a sampled area of 4200 km2, the distribution of 615 known blowholes is not correlated with present topography. Blowholes are often connected to small or, in some cases extensive, but typically shallow cavities, which exhibit numerous ‘cupolas’ (dome‐shaped pockets) in their ceilings. Statistical arguments suggest that cavities with cupolas are common, but in only a few cases do these puncture the surface. Hardness measurements indicate that salt weathering is not their main cause. Our observations suggest that blowholes do not develop downwards, but occur where a cupola breaks through the surface. Lowering of the land surface is suggested to be the main cause for this breakthrough. Although cupolas may undergo some modification under the current climate, they, as well as the shallow caves they are formed in, are likely to be palaeokarst features formed under a shallower water table and wetter conditions in the past. The findings presented have implications for theories of dissolutional forms development in caves worldwide. The environmental history of the Nullarbor platform allows testing of such theories, because many other factors, which complicate karst evolution elsewhere, have not interfered with landform evolution here. Copyright © 2011 John Wiley & Sons, Ltd.

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Karst evolution of the Nullarbor Plain, Australia

Cited by 39 publications

References 11 publications

EarthSciencesComparativeMatrix: A Comparative Method for Geoheritage Assessment

EarthSciencesComparativeMatrix: A Comparative Method for Geoheritage Assessment

Microbial Populations of Stony Meteorites: Substrate Controls on First Colonizers

Origin and karst geomorphological significance of the enigmatic Australian Nullarbor Plain ‘blowholes’

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