Landforms Are Not Static

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An examination of micro-erosion meter results from various sites in Australia, over the period 1978 to present.

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Landforms Are Not Static

  1. 1. Landforms are not static – geodiversity & geoheritage in a changing world Stephen Swabey, Dingle Smith Andy Spate, Dave Lambert Linnean Society meeting, 6-10 September 2010
  2. 2. Landforms are not static <ul><li>Rock surface lowering affects landforms </li></ul><ul><li>Rates of lowering a function of: </li></ul><ul><ul><li>Natural processes </li></ul></ul><ul><ul><li>Human interventions </li></ul></ul><ul><li>Affects geodiversity & geoheritage through </li></ul><ul><ul><li>Destruction </li></ul></ul><ul><ul><li>Alteration </li></ul></ul><ul><li>Changes through time – how quickly? </li></ul>
  3. 3. Micro-Erosion Meter Sites <ul><li>Micro erosion meter (MEM) invented by High & Hanna to directly measure rock surface lowering over time </li></ul><ul><li>Used world-wide </li></ul><ul><li>Mainly on coasts & karst but also on built structures & archaeological sites </li></ul><ul><li>Four traversing MEMs used in this study </li></ul><ul><li>Measuring periods range from 2 to 32 years </li></ul>
  4. 4. Locations – NSW Buchan Bouddi Mutawintji Yengo Brisbane Water Ku-ring-gai Chase Jenolan Kosciuszko Wombeyan New South Wales Ginninderra
  5. 5. Locations - WA Geikie Gorge Windjana Gorge Tunnel Creek Napier Ra. Oscar Ra. DERBY Western Australia FITZROY CROSSING
  6. 8. Site geologies <ul><ul><li>Cooleman Plain (5 sites) – Silurian limestone </li></ul></ul><ul><ul><li>Yarrangobilly (6) – Silurian limestone </li></ul></ul><ul><ul><li>Kimberley (17) – Devonian limestone </li></ul></ul><ul><ul><li>Ginninderra (9) – Limestones from across Australia </li></ul></ul><ul><ul><li>Archaeological sites (5) – Sydney Basin sandstones & Mutawintji Group Ordovician to Devonian sandstones </li></ul></ul>
  7. 9. Rates of Lowering – Sub-alpine karst Cooleman Plain 1978-2010 (mm/1,000 years) 16.4 7.8 9.1 20.3 48.8 Solution ripples Bedrock (convex) Bedrock (concave) Cave stream Sinking stream Kosciuszko National Park
  8. 10. Rates of Lowering – Sub-alpine karst Yarrangobilly 1978-2010 (mm/1,000 years) 18.4 9.7 13.9 93.5 7.4 Solution flutes Bedrock (convex) Bedrock (concave) Kamenitza Bedrock (litter covered) Kosciuszko National Park
  9. 13. Rates of Lowering – Tropical seasonally moist karst 2008 – 2010 (mm/1000 years) 47.4 32.3 24.2 20.5 45.6 Napier Range, Oscar Range 44.7 37.6 Fore reef Reef crest Back reef Fore reef Vertical run-on Kamenitza Reef crest (micritic)
  10. 14. Rates of Lowering – Tropical seasonally moist karst 1988 – 2010 (mm/1000 years) 98.7 85.6 70.0 50.9 49.7 64.9 Pediment Creek bed Pediment Buried (soil) Pediment Kamenitza Pediment Napier Range 2494
  11. 16. Sydney Basin Sandstone archaeological sites 1978-1983/6 (mm/1,000 years) 309 9.9 15.0 49.7 35.9 Bouddi- Milligans Bulgandry Burragurra NW Ridge Daley’s Point rock shelter (1978-2010) Sydney basin sandstone
  12. 17. Ginninderra 1979-2010 (mm/1000 years) 5.1 5.6 4.3 6.8 9.9 23.9 Yarrangobilly Wombeyan Buchan Bungonia Mt Gambier 5-year Nullabor Cooleman Ginninderra Rock Garden Mt Gambier 100 year Wilsons 2.9 4.7 4.7
  13. 19. Uniform Climate… <ul><li>At Ginninderra same rainfall/temperature </li></ul><ul><ul><li>Rainfall 615.4 mm, 72 raindays (1939-2010) </li></ul></ul><ul><ul><li>Temp. monthly means </li></ul></ul><ul><ul><ul><li>-0.1 o C (minimum - July) </li></ul></ul></ul><ul><ul><ul><li>28 o C (maximum – January) </li></ul></ul></ul><ul><li>Relatively similar rates of lowering, except Wilson’s Bluff (Nullarbor) </li></ul>
  14. 20. Comparing all rates of lowering… 9.9 98.7 37.6 5.1 5.6 4.3 6.8 23.9 Ginninderra Rock Garden 2.9 4.7 4.7 309 9.9 15.0 49.7 35.9 Sydney basin sandstone 2494 85.6 70.0 50.9 49.7 64.9 Napier Range 47.4 32.3 24.2 20.5 45.6 Napier Range, Oscar Range 44.7 7.4 18.4 9.7 13.9 93.5 Yarrangobilly 16.4 7.8 9.1 20.3 48.8 Cooleman Plain
  15. 21. Some Conclusions… <ul><li>Tropical karst lowers faster than sub-alpine karst; Sydney sandstone in between </li></ul><ul><li>Individual landforms can lower rapidly </li></ul><ul><ul><li>Karst stream 2.5 m in 1000 years </li></ul></ul><ul><ul><li>Mossy kamenitza 94 mm in 1000 years </li></ul></ul><ul><ul><li>Rock shelter floor 309 mm in 1000 years </li></ul></ul><ul><li>Low-profile landforms may evolve quickly </li></ul><ul><li>Climate is a strong control on rates </li></ul>
  16. 22. So what can this be used for? <ul><li>Context for geomorphological processes/rates </li></ul><ul><li>Identifying ‘hot-spots’ of process rates </li></ul><ul><li>Significance of landforms in landscape </li></ul><ul><li>Visitor impacts on geodiversity/geoheritage (eg, Viles’ work in UK – 139 mm/1000 years)? </li></ul><ul><li>Interpretation for geotourism (eg, Mutawintji) </li></ul><ul><li>Focus for future management approaches </li></ul>
  17. 23. Thanks… <ul><li>The late Joe Jennings </li></ul><ul><li>DECCW (NSW) for site access </li></ul><ul><li>DEC (WA) for site access </li></ul><ul><li>CSIRO GES for rock garden site </li></ul><ul><li>Landowners (WA) for site access </li></ul>

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