| Darling Scarp | |
|---|---|
| Katta Moorda | |
 Darling Scarp as viewed from Sullivan Rock (September 2022) | |
| Highest point | |
| Peak | Mount Cooke |
| Elevation | 582 m (1,909 ft) AHD |
| Geography | |
 | |
| Country | Australia |
| State | Western Australia |
| Geology | |
| Formed by | Darling Fault |
| Rock age | Cenozoic |
TheDarling Scarp (Nyungar:Katta Moorda),[1] also referred to as theDarling Range orDarling Ranges, is a lowescarpment running north–south to the east of theSwan Coastal Plain andPerth,Western Australia. The escarpment extends generally north ofBindoon, to the south ofPemberton. The adjacent Darling Plateau goes easterly to include Mount Bakewell nearYork and Mount Saddleback nearBoddington. It was named after theGovernor of New South Wales, Lieutenant-GeneralRalph Darling.
The feature was first recorded as General Darling Range byCharles Fraser, Government Botanist with CaptainJames Stirling aboardHMS Success in March 1827.
Maps from the 1830s show the scarp labelled "General Darlings Range"; this later became Darling Range, a name by which the formation was still commonly known in the late 20th century despite common understanding of it being an escarpment. There is also a tendency to identify the locations on or to the east of the scarp as being in the "Perth Hills" (or simply "The Hills").
The earliest traverses byBritishsettlers in theSwan River Colony occurred in the 1830s. The best known of these is the expedition ofEnsign Robert Dale, who appears to have gone from a point nearGuildford, to the south side ofGreenmount Hill and up through theHelena Valley.[2]
The Darling Scarp originated as the local expression, in the Perth area, of the extensiveDarling Fault, a major and ancient geological discontinuity separating theArchaeanYilgarn Craton in the east from the youngerPinjarra Orogen and overlyingPhanerozoicPerth Basin to the west. The Darling Fault is exposed for over 1,000 kilometres (620 mi), from the area east ofShark Bay, to the southern coast of Western Australia east ofAlbany. The location of the scarp must once have coincided with the location of thefault, but the scarp has since eroded about 15 kilometres (9.3 mi) eastwards. The original location of the scarp is indicated in places by an unusual landform known as theRidge Hill Shelf.
The Darling Plateau is covered by lateritic materials that cover the underlying geology.[3][4]
The Archaeangranites andgneisses of the Yilgarn Craton form the high ground of the Perth Hills and can be observed in road cuts, with good examples in theMundaring Weir area. The only exposed sediments of the Perth Basin, west of the fault, are ofCenozoic age, and are composed of materials such as sandylimestone,travertine and dune sand on which the city of Perth is built, including sand dunes ofPleistocene age formed during thelast glacial period.
This area is also a distinct physiographic section of the largerYilgarn Block province, which in turn is part of the largerWest Australian Shield division.
The Scarp, like the rest of south west Australia, has a Mediterranean climate, with mild rainy winters and warm dry summers. Average annual rainfall is 1300 mm along the scarp, declining to the east and north.[5]
Often theBureau of Meteorology identifies different weather for "the hills" in comparison to that of theSwan Coastal Plain.[6]
Also, in traditionally hot summers, strong easterly winds travelling across the scarp have presented serious issues for planes using thePerth Airport because of the alignment of the runways.[7] On 2 September 1999, the number one engine of aQantasBoeing 747, en route fromSydney Airport coming into land on Runway 06/24, struck the runway surface upon landing, due towind shear caused by rolling winds on the Darling Scarp.[8] In addition, orographic uplift is produced when rain clouds move over the hills, giving higher rainfalls in settlements in the ranges compared with their coastal neighbours.
The scarp is part of theJarrah Forest bioregion. The natural vegetation of the scarp is predominantlyjarrah–marri forest, characterised byjarrah (Eucalyptus marginata) andmarri (Corymbia calophylla), withbullich (Eucalyptus megacarpa) andblackbutt (Eucalyptus patens) in the valleys.[5] TheDarling Range ghost gum (Eucalyptus laeliae) is endemic to the western slopes of the scarp.
Heath is found on granite outcrops. Low woodlands ofBanksia grow on sand sheets.[5]
Native mammals include thequenda (Isoodon fusciventer),chuditch (Dasyurus geoffroii),woylie (Bettongia penicillata ogilbyi), andbrush-tailed phascogale (Phascogale tapoatafa wambenger).Quokka (Setonix brachyurus) andwestern ringtail possum (Pseudocheirus occidentalis) are often restricted toriparian areas.[5]
The Darling escarpment has been exploited for stonequarries,forestry andbauxite mining. Extensivetimber railways and timber mills and the supporting communities existed along the escarpment because of the high qualityjarrah forests.[9]
In the early twentieth century, most of the main rivers flowing off the escarpment had mainly been used for dams for water supply for metropolitan Perth. The dams on the scarp include:
The only free flowing water from the Darling Range in the Peel Region is the Dirk Brook inKeysbrook and theMurray River.
The scarp also defines the easternmost limit of the variousaquifers present in the Perth Basin sediments, most notably the SouthwestYarragadee Aquifer. The scarp forms a divide between the hypersaline groundwaters typical of the Yilgarn Craton basement from the fresh ground waters of the Perth Basin. Some dams along the scarp are contaminated by seepage of saline water from the granite into the base of the dam's water column and must be periodically flushed to preserve water quality.
Also in the early to mid-twentieth century numerous rock quarries existed on the edge of the escarpment - visible and affecting both the aesthetics and the environment of the escarpment.
In the area where theHelena River emerges from its valley to thesandplain, there are still four quarries evident, despite being unused as quarries for fifty years or more. Mountain[10] and Stathams[11] quarries are now managed as rock climbing locations.
There have also been visible quarries on the scarp in theGosnells andHerne Hill areas.
Legislative restrictions upon such developments were initiated in the late twentieth century to prevent further visible scars on the western face of the scarp.
In the late twentieth century, the proving of bauxite deposits correlating to the extensivejarrah forests saw wide-ranging protests against the proposals to mine the forests.Campaign to Save Native Forests was one group to oppose the activity.
The lengthy process of protest forced the government and miners to check their original proposals, and wide-ranging processes to guard segments of the jarrah forests from mining ensued.
The current mining activity in the region is extensive - the main mines being Huntly and Willowdale.[12]
The building and developing of rail access across the scarp developed three separate main routes over eighty years.[13]
The localities or suburbs on the "edge" of the scarp are those that sit at its western edge, and in most cases command excellent views of theSwan Coastal Plain:
The suburbs near Midland and Kalamunda are often referred to as thePerth Hills.
The suburbs to the south of Kalamunda are the locations of the main Perth Metropolitan television station transmission towers. There is also another site at Mount Lennard nearCollie that Services the Southwest areas includingBunbury.
Also in the late twentieth century,dieback affecting jarrah timber in particular infected large tracts of the forest. Currently only the restriction of vehicle access has proved effective in slowing the spread of this disease. This gained greater acceptance and publicity through the decision to allowRally Australia to operate along services roads provided that the vehicles had a thorough wash including the under carriage at the end of each stage.
In late 2004, the largest bushfire in the northernJarrah Forest for at least 100 years created significant issues for the forest as well. As a result of this fire intensity the Government increased the volume of controlled burns along the entire escarpment to reduce the buildup of flammable materials.
In the early 2000s,Greenmount National Park andJohn Forrest National Park were repeatedly burnt by bushfires - in most cases through suspected arson.
A network of reserves of crown lands on the escarpment have been connected into a regional park to maintain and conserve parts of the escarpment.
In most cases the reserves or parks had individual names prior to being incorporated into the larger park, for example theSerpentine National Park,John Forrest National Park and theGreenmount National Park, or were simply known as State Forests (e.g. State Forest No.42).
Following a change in 2005, the separate parks have been known as the "Parks of the Darling Range", and take up 23,948 hectares on the scarp.[14] Further in August 2008 the parks were given indigenous names:[15]
| International | |
|---|---|
| National | |
