The Kimberley (or Tasman Land) forms the northwestern part of the Great Australian Penepian. It differs from most of this mainly in having an annual precipitation above 500 mm; it consists of different soils eroded to varying degrees. The highest point is Mount Hann (853 m.). Due to the considerable rainfall, the penepiano, already almost leveled and then raised again, was sculpted in mountains and valleys. Some of the more resistant rocks emerge as steep cliffs that form part of the so-called King Leopold, Geikie and Napier Range, crossed in some places by streams in deep winding gorges superimposed (antecedents). It has been assumed that rivers originally flowed southwest (such as Sturt Creek today) and were then captured by westward flowing coastal courses. The main one is the Fitzroy, about 563 km long, which after the summer rains brings an enormous volume of water to the sea. It flows over vast and low grassy plains, which at times, as in 1914, are flooded with them for a width of over 30 km., While during the dry months the river does not flow and shows along its course only large pockets of water. water. The Kimberley coast is characterized by a number of narrow and deep gulfs (rias), due to a relatively recent marine transgression in large river valleys. The tide reaches a height of 7 and a half meters in various points of this coast.
The desert region comprises the large uninhabited area extending east of a line from the River De Gray to Laverton, and extensively penetrating South, Central and Northern Australia. Its topography is known well enough for reports made by Talbot, Clarke, Carnegie, Clapp and others. The average level is about 450 m. and there are no notable topographical features other than salt lakes, of shallow depth, and insignificant relief lines which geologists consider valley edges of a remote wet age (Great Sandy Desert and Great Victoria Desert).
The north-western coastal area extends from the De Gray river to the Murchison: it is a raised edge of the penepian, which reaches 1226 m. to M. Bruce, traversed by fold or fracture escarpments, and plunging into the eastern sandy desert. The most important area is constituted by the plateau called Hamersley and Ophthalmia Range, limited to the north by a marked fracture wall, along which the Fortescue flows. The whole internal portion of the region presents undulations in a state of advanced topographical maturity, with large flat surfaces crossed by small reliefs. Spinifex (Triodia) forms the common vegetation of the high basins of Ashburton and Fortescue, while mulga (Acacia). Towards the headwaters of the Murchison, there is another large extension above 600m. which can take the name of Wiluna’s highlands, made up of rocky reliefs and arid plains with very few inhabited centers.
The south-western temperate region, endowed with sufficient precipitation for agriculture, and with fairly dense settlements, has been given the name of Swanland (Swanland): it is a part of the great penepian that has suffered for a long time erosive action of many rivers and streams, so its topography is very different from that of the rest of Western Australia. The raised fracture of the Darling Mountains, an escarpment that extends for about 300 km. from Moora to the south, it separates the coast from the interior, which has been eroded into large valleys in which the rivers, with an old aspect, meander. A subsidence, particularly noticeable near Perth, has produced the Swan River estuary. The origin of the relief near Cape Leeuwin seems to be due to a small local uplift. The Mount Stirling chain, 80 km long, is made up of quartzites, which have perhaps been pushed as a single block to a height of 900 m. This movement seems to have occurred rather recently, as small lakes and hanging valleys still show the disturbance that interrupted the ancient outflow. The Gulf of King George in Albany is a fine example of a submerged coastal valley. For Australia democracy and rights, please check localbusinessexplorer.com.
Between the Land of the Swans and the desert extends the region of the salt lakes, which has between 200 and 250 mm. of annual rain. The numerous lakes (playas) are shallow, elongated in shape, some extended in length up to 80 km. and about 8. They occupy small cavities of the penepian, and many theories have been advanced to explain their origin: but it is probable that they are remnants of river valleys from the Tertiary period. The lakes north of Kalgoorlie (Raeside, Darlot Salt and Carey) appear in fact portions of a river that once flowed from the southeast to Goddard’s Creek and then to the great southern gulf. Gregory believes that these rivers could not keep their course clear of encroaching sand dunes during post-Miocene desiccation. And, as Tutson has shown, desert erosion has subsequently attacked the emptied lake basins, so that they often have flat, rocky bottoms edged by almost vertical walls. Sheer rocky islands also emerge from the level floor like a billiard table. The water in these lakes evaporates quickly, but it can be obtained from underground easily, almost everywhere. In the south it is often salty, but in the north it is sweet, and the region is therefore largely occupied by livestock.
The (synclinal) region of Nullarbor (or Nullabor), south of the Great Desert, consists of a vast plateau of relatively recent Cretaceous limestone rocks in the north, similar to those of the Queensland artesian basin, covered in the south by Tertiary (Miocene) which also form the high coastal bank (60 m.) of the Gran Baia or Bight. From this the plateau gradually rises towards the north up to 350 meters. The cavernous limestone, which has 250 m. thick, quickly absorbs rains; hence the lack of surface water, which prevented colonization.
To a great extent the Northern Territory is part of the Great Penepian which, as we have seen, was partially raised during the Middle and Upper Tertiary. Jensen believes that this rise has continued to the present time and that this is indicated by the raised beaches seen on most of the coastline, and by the cañons. of the Katherine and MacArthur Rivers. Inside, there is no trace of river erosion. The northern or coastal portion of Northern Australia appears to have a height of 150 to 300 meters, but a part of the Land of Arnhem, not yet fully explored, perhaps reaches a greater height. Most of the waters flowing south from the Barkley Plateau collects in vast shallow basins that become true lakes during the wettest seasons. Thus Lake De Burgh (near Brunette Downs) can sometimes spread over a space of about 160 km., While it generally divides into a series of marshy areas at the lower end of the creeks. Playford, Creswell et al. Lake Woods (near Newcastle Waters) is another similar basin, but has now almost disappeared. The southernmost region of the Territory is higher and more arid. A large area south of Powell Creek and the Barkley Plateau is little known, although the route along the transcontinental telegraph is often traveled. To the west it touches the outskirts of the Great Desert, between Tanami and Barrow Creek, to the east the smaller but equally depopulated area, which has been assigned the name of Arunta desert. These inhospitable regions have more or less vegetation of mulga shrubs or spinifex patches. They show the characteristic aspect of desert erosion in the vast, monotonous succession of sand dunes, generally fixed by vegetation, oriented towards the roughly from north-west to south-east. There are also stony plains, here and there sandy valleys and bare pockets of clay.
The Barkley plateau (350 m.), On the north-eastern edge of the penepian, is made up entirely of ancient rocks with various notable mines, such as those of Cloncurry and Mount Isa. Towards Cammooweal there are interesting sinkholes in the porous limestone, and the rivers of the Gulf of Carpentaria are fed by springs that gush at the base of similar limestones. In its western part the region looks like a slowly inclined plane with the highest edge towards the coast and constitutes a grassy country important for the breeding of livestock, which however suffers from the lack of permanent water on the surface; deep wells also provide it in abundance.
The Mac Donnell Mountains, consisting of east to west direct hills emerging on the general penepiano, rise to 1470 m. (see mac donnell, mountains). At 1585 m. in a rounded granite massif (Mount Woodroffe) come the Musgrave Mountains, south of the previous ones, on the edge of South Australia. The Everard Mountains, south of the Musgraves, consist of domed hills emerging from the penepian which is here at about 520m. In the lower part of the region near the center of the state, sandstones in almost horizontal layers, very compact, have formed a kind of very resistant cover that has been eroded into tabuliform heights or mesas, while the fragments of it have given rise to the typical desert pebbles known by the native name of gibber. Wind-blown dunes are common at the intermittent course of the Alberga River.