Hallett Cove Conservation Park
Hallett Cove Conservation Park South Australia | |
---|---|
Nearest town or city | Adelaide |
Coordinates | 35°04′25″S 138°29′57″E / 35.07361°S 138.49917°E |
Established | 1 July 1976[2] |
Area | 51 ha (126 acres)[3] |
Managing authorities | Department for Environment and Water |
Website | Hallett Cove Conservation Park |
See also | Protected areas of South Australia |
Hallett Cove Conservation Park is a protected area in the Australian state of South Australia located in the suburb of Hallett Cove on the coast of Gulf St Vincent about 22 kilometres (14 miles) south of the centre of the state capital of Adelaide.
Hallett Cove is one of the best known geological sites in Australia and is known for its international significance. The area has been declared a Geological Monument by the
Some of the features in the park are Waterfall Creek, Black Cliff and the Amphitheatre. A freshwater spring near Waterfall Creek is one of the features of the
History
Aboriginal occupation
Although Kartan tools are traditionally made of quartzite, often sourced from great distances, all of the finds at Hallett Cove were made of siltstone despite large amounts of suitable quartzite being available on the beach. During the late Pleistocene, the sea level was around 90 metres (300 ft) lower than today. From 85,000 to around 15,000 years ago, the present Gulf St Vincent was a deep river valley to the west while the nearest site of exposed quartzite was likely near the coast, which during that time lay some 350 kilometres (220 mi) to the south. It has been suggested that a debris slope may have stretched far into the gulf, covering the local quartzite which had likely eroded out only after the present coastline was established around 6,000 years ago. The finds include a number of very well made quartzite tools of the type in use when Adelaide was settled.[5]
More recently, the
Hallett Cove is a place of significance to the Kaurna people because of its association with
The spring, and Hallett Cove more broadly, has in the past mistakenly been ascribed the place name Krildhung (by Albert Karlowan) or Ka`reildung (Norman Tindale); however, this word is derived from a verb in the Ngarrindjeri language, but this has been found to be the result of mistaken location. A Kaurna version of the meaning of this word ("crying place") was created in 2008 as Murrkangga, and applied to the Amphitheatre.[6]
European occupation
After the British colonisation of South Australia, Hallett Cove was named for John Hallett, who travelled into the area while searching for lost stock in 1837. In the 1840s the cove was used by smugglers to land goods at night which were then taken to Adelaide by dray. In 1847, the Worthing Mining Company purchased 800 acres (320 ha) from the Hallett family and built a copper mine on the northern side of Hallett's creek, now known as the Field River. However, the ground proved to be too hard and water kept flooding the diggings. In 1852 the miners left for the Victorian gold rush and the mine was finally abandoned in 1857. Farming began in what is now the eastern section of the park in the 1850s. In the late 1880s the cove was used for naval exercises and the southern area of beach was cleared of rocks to allow landings.[5]
Professor Ralph Tate realised that South Australia had been subjected to an ice age when in 1877 he discovered the area's smoothed and striated glacial pavement. In 1893, "the largest scientific excursion ever held in the Southern Hemisphere" explored the area with Prof. Walter Howchin later demonstrating that the deposits were of Permian age and that Australia was closer to the south pole than today while part of the Gondwanan supercontinent. During that time the south-western two-thirds of Australia, including much of South Australia was covered by an ice sheet. The first detailed description of the geology of the area was published in 1943.[5]
In 1957 Professor A.R. Alderman from the University of Adelaide wrote to the
In 1965 subdivision of the adjacent land for housing was announced. For the next 11 years conservationists fought against developments. In late 1969, the State Planning Authority declared 51 acres (21 ha) of Hallett Cove a site of scientific interest which prohibited landowners from developing the land in any way that would destroy its scientific value. In 1970 it was announced that the surrounding land would be subdivided and a large private marina built in the cove. The government received tens of thousands of letters of protest and significant public debate ensued. Premier Dunstan guaranteed to protect the area and the government later acquired the cove and a further 67 acres (27 ha) of land.[5]
Conservation park
In 1976, the park was declared a Conservation Park dedicated for the protection of features of geological and historic interest.[citation needed]
After the creation of the Glenthorne National Park–Ityamaiitpinna Yarta in 2020, Hallett Cove Conservation Park became part of the Glenthorne Precinct, along with Marino Conservation Park, areas of the Field River valley and Happy Valley Reservoir.[8]
Geology of the park
Late Precambrian
Ripple marks in the oldest Hallett Cove rocks indicate that the sediments that formed them originated on a
From around 550 Ma the beds of the Geosyncline began a series of intraplate extensional and contractional events. The beds began to buckle, fold, uplift and
Today, the remains of the southern section of the Cambrian mountain range are known as the Mount Lofty Ranges which have eroded down to below 730 metres (2,400 ft).
Permian
The 600 Ma Precambrian rocks at Hallet cove are separated from the 270 Ma Permian deposits by an unconformity. If there were periods of deposition between the two periods, erosion has removed all trace.
The formation of
Hallett Cove at this time was part of a river valley orientated with the mountain range to the NE. Ice had scoured a basin and meltwater from the retreating glacier formed a lake which deposited the sediments that can be seen today along the clifftops. Although no fossils have been found in these sediments, arthropod trails have been found in similar sediments further south. Dropstones and erratics, rocks carried by glaciers which drop when they melt, litter the beach where the Permian sediments that once held them have long since been eroded away. Smaller ones can be found still embedded in the sediments. Most of the dropstones, some bigger than cars, originated from sites hundreds of km to the south, however, several consist of rock not found in South Australia and their origin has yet to be determined. One erratic currently eroding out at the top of Black Cliff is dated 400 Million years older than the oldest Hallett Cove rocks. Made of Tillite, it is the earliest evidence of glaciation ever recorded.[5]
Pliocene
A second period of erosion began around 250Ma which removed most of the Permian sediments in the region with the exception of some that were protected by the Hallett cove basin. This forms the second unconformity that separates the Permian from the Pliocene deposits.
By the Cenozoic, the Mt Lofty Ranges had worn down to sea level. A period of faulting commenced which uplifted the ranges and downthrust the plains which, beginning 50Ma was flooded by the sea. By 20Ma the land west of the ranges was a shallow sea. Hallett Cove has no sediments from this period indicating it may have been above sea level, an island in a shallow sea.
Further faulting raised the Mt Lofty Ranges to a little higher than their current elevation and submerged Hallet Cove. Dated at 5Ma to 3Ma, a band of sandstone that had been laid down on a sea floor can be found overlaying the Permian deposits. This layer contains fossil shells and limy sands. Overlaying the sandstone is a considerable thickness of mottled clays with patches of sand and gravel, the sediments washed down from the slopes of the Mt Lofty Ranges from 3Ma to 1Ma when the area was a river
Pleistocene
The Pleistocene climate was marked by repeated glacial cycles. During the early pleistocene the rapid accumulation of clays indicates a much wetter climate than today. Following the end of the last glaciation 15,000 years ago, the climate appears to have dried out somewhat as a layer of calcrete overlays the clay deposits. The Gulf St Vincent was an alluvial plain drained by an ancient river when Aboriginals first settled on the Hallett Cove clifftops and their tools have been found in the sand that lies above the calcrete.
Recent
As the glaciers retreated in the Northern Hemisphere, the sea levels rose worldwide. The current sea level stabilised around 6,000 years ago and began to erode the Hallett Cove cliffs. As the folds in the cliff face are almost vertical, the cliff face retreats as the sea breaches the quartzite layers that protect the softer siltstone layers between them forming the zigzag pattern we see today. As the cliff retreats it leaves a wave cut platform behind.
The Amphitheatre is a feature of the park where the Precambrian rocks are below sea level. Without their protection erosion is rapidly cutting through the soft Permian, Pliocene and Pleistocene deposits resulting in a badlands terrain. As the silts are eroded erratics are released which roll down to the base platform and beach.
An interpretative walking trail describes the park's cultural and geological heritage.[12]
See also
- List of protected areas in Adelaide
- Adelaide Rift Complex
References
- ^ "Terrestrial Protected Areas of South Australia (refer 'DETAIL' tab )". CAPAD 2016. Australian Government, Department of the Environment (DoE). 2016. Retrieved 21 February 2018.
- ^ Chatterton, Brian (1 July 1976). "NATIONAL PARKS AND WILDLIFE ACT, 1972-1974: HALLETT COVE CONSERVATION PARK CONSTITUTED" (PDF). The South Australian Government Gazettee. Government of South Australia. p. 7. Retrieved 5 December 2018.
- ^ "Protected Areas Information System - reserve list (as of 25 November 2014)" (PDF). Department of Environment Water and Natural Resources. Retrieved 8 January 2015.
- ^ a b Coastal Management Study, Hallett Cove, SA (PDF) (Report). Report No. R11‐008‐01‐01. Coastal Environment Pty Ltd. 14 June 2012. Retrieved 18 November 2020.
Prepared for the City of Marion.
- ^ a b c d e f g h i j Cooper, H. M. (Harold Moore), 1886-1970; Kenny, M. (Margaret); Scrymgour, June M; South Australian Museum (1970), Hallett Cove: a field guide / by H.M. Cooper, M. Kenny, J.M. Scrymgour, South Australian Museum
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: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link) - ^ a b Schultz, Chester (22 April 2016). Place Name Summary (PNS) 3/10: (a) Krildhung and (b) Murrkangga (PDF) (Report). The Southern Kaurna Place Names Project. University of Adelaide.
- ^ Malone, Gavin Damien Francis (2012). "Chapter 10: Kaurna Ancestor Being Tjilbruke: Commemorations". Phases of Aboriginal Inclusion in the Public Space in Adelaide, South Australia, since Colonisation (PhD). Chapter 10 PDF. Flinders University. p. 217. Retrieved 17 November 2020.
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: External link in
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- ^ "Glenthorne National Park-Ityamaiitpinna Yarta". Glenthorne National Park. 12 July 2021. Retrieved 19 December 2021. Text may have been copied from this source, which is available under a Attribution 3.0 Australia (CC BY 3.0 AU) licence.
- ^ Cooyerdoo Rocks, located 375 kilometres (233 mi) NW of Hallett Cove are dated to 3,157 ± 2 Ma
- ^ This mountain range may have been the southern extent of the Petermann Orogeny and part of a suspected Supermountain range that may have stretched more than 8,000 kilometres (5,000 mi) through the newly forming Gondwana supercontinent. The uplifting was so violent that despite now being located in the center of a plate, the Flinders Seismic Zone of which Hallett Cove is part remains one of the most seismically active regions in Australia.
- ^ a b Australia in time and space Australian National University Pg 84 - 104
- ^ Hallett Cove Conservation Park Archived 21 April 2012 at the Wayback Machine Parks SA
Further reading
- Major, R. B; Giesecke, R; Whatmough, R; Field Geology Club of South Australia (1999), A field guide to the geology of Hallett Cove and other locations with glacial geology on Fleurieu Peninsula (1st ed.), Field Geology Club of South Australia, ISBN 978-0-9596596-3-4
External links
- Hallett Cove Conservation Park Archived 21 April 2012 at the Wayback Machine South Australia Department of Environment and Natural Resources. This site includes a pamphlet containing a map of the walking trails. Accessed 22 April 2012.
- "Hallett Cove Conservation Park". City of Marion. Retrieved 2 May 2015.
- Hallett Cove Conservation Park webpage on protected planet