Cape pleated belt
| Cape Fold Belt | ||
|---|---|---|
| Highest peak | Seweweekspoortpiek (Swartberge) ( 2325 m ) | |
| location | Western Cape Province ( South Africa ) | |
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| Coordinates | 33 ° 24 ′ S , 22 ° 0 ′ E | |
The Cape Fold Belt (also: Cape Fold Belt ) is a type of landscape in South Africa , resulting from the combination of a plurality of mountains and the provinces of Western Cape and the western part of the Eastern Cape impressed. It consists of a series of unfolded sedimentary rocks and covers large parts of the southwest corner of South Africa with table mountain sandstone .
Mountain landscapes of the Belt
The fold belt opens up behind the numerous bays and headlands of the Western Cape and covers territories that lie about 400 km to the north from the Cape of Good Hope and about 500 km to the east in the hinterland of the coastal strips of the Atlantic and Indian Oceans . Along the Garden Route (from Mossel Bay to Plettenberg Bay ) the belt with the Outeniqua Mountains , the Kouga -Moutains and the Tsitsikamma Mountains comes close to the coast. From the eastern limb of False Bay the Hottentots Holland Mountains pull northwards, which merge into the Boland Mountains . To the west are the cedar mountains . Deeper inland, the Langeberg Mountains and the Swartberge await eastwards . With the Seweweekspoortpiek the Belt in the Swartberg Mountains reaches its highest point (2325 m).
geology
The fold belt consists of table mountain sandstone, thus a sediment sequence of various quartzitic sandstones and slate formations . It extends from Nieuwoudtville over the Table Mountain region near Cape Town to the tip of the Cape Peninsula and into the region of the more distant Port Elizabeth . Within the lithostratigraphic contexts of South Africa, the Cape Fold Belt belongs to the Table Mountain Group , which, in terms of age, can be assigned to the Middle Paleozoic and is considered part of the Cape Supergroup .
The current rocks of the Belt have their origin in the geological age of the Ordovician , a chronostratigraphic system of the Paleozoic Era . During this phase, the rock layers were superposed in a discordant manner. Fine-clastic sedimentary rocks such as silt and clay stones as well as Grauwacken from the older Malmesbury group were superimposed . During the Carboniferous and the subsequent Permian , the unfolding continued and led to the merger into the supercontinent Pangea .
Mountain building (Age of the Karoo Supergroup)
The mountains of the Cape Belt are not particularly old, despite the appearance they convey. They were formed under the collision forces when the supercontinent Pangea formed about 300 million years ago during the Permian. Its structure is very weatherproof due to the quartz-containing sandstone and clayey slate formations. Alluvial soils on the sea coasts as well as river and lake banks filled the resulting (deeply cut) valleys in the Quaternary .
The Karoo supergroup was formed 300 to 200 million years ago . Sediment formation within this supergroup began in the Carboniferous with the glacial deposits of the Dwyka group ( Dwyka- Tillite ). Massive folding movements were the cause. Marine sediments were deposited on top. Fluvial sediments were deposited over these layers . These overlays first gave the Ecca and later the Beaufort group . The exposed sediment sequences of the Beaufort group are susceptible to weathering. They break up easily and form only thin soils of sand and silt . Intensive use of the soil intensified this development and erosion channels ( gullies ) were created. By soil erosion valuable ecosystems and agricultural land destroyed. In addition, the soil washed away by surface water pollutes the rivers with large amounts of mineral suspended matter that can render dams and other water management systems inoperable. Important fossil reptile species found in this group are Cistecephalus ( Dicynodontia ), Cynognathus , Eodicynodon , Lystrosaurus , Pristerognathus , Procolophon , Tapinocephalus and Tropidostoma .
In the end, violent lava pouring from the Drakensberg Formation covered the existing sediments, so that ultimately layers of sediment were deposited on top of sediment layers and compacted in the process. The disintegration of Gondwana finally caused violent magmas to rise and volcanism set in. Extreme temperatures arose. The pressure on the rock material was just as extreme, so that the superimposed layers of sediment were enormously solidified, twisted and anticlines formed. Even today, the landscape of the Cape Fold Belt testifies to these processes in a sometimes spectacular way.
It is noticeable that these sedimentary structures often run parallel to the coastlines, which is due to the fact that during the Jurassic , about 120 million years ago, when the ancient continent Gondwana broke up into the African and South American continental masses, tremendous frictional forces along their course occurred. Until then, today's Patagonia was west of today's Cape Town and the Falkland Islands south of it. With the lowering of the continental crust on the two oceans, the Karoo supergroup concluded at the time of the overlap from Jurassic to Chalk .
Landscapes of the Cape Fold Belt
- Cedar Mountains
- Olifants River Mountains
- Piketberg ( Piketberg )
- Winterhoekberge
- Skurweberge
- Hex River Mountains
- Du Toitskloof Mountains
- Drakenstein Mountains (Drakenstein)
- Simonsberg
- Hottentots-Holland Mountains
- Kogelberg
- Stettynsberg
- Langeberg
- Riviersonderend Mountains
- Kleinrivier Mountains
- Witteberge
- Swartberg
- Outeniqua mountains
- Langkloof Mountains
- Kouga Mountains
- Tsitsikamma Mountains
- Baviaanskloof
- Zuurberge
climate
The climate of the Cape Fold Mountains is subtropical, Mediterranean with rainy winters, with peak rainy times to the east at the beginning of spring and the end of autumn. Uniform year-round precipitation can be measured at Port Elisabeth on the eastern edge of the Belt. An annual average of up to 2500 mm of precipitation can be expected there. To the west, precipitation decreases in the coastal area, as the Outeniqua and Tsitsikamma mountains act like a weather divide. There, an average of 750 mm of rain falls in the vicinity. Inland (especially in the west of the Belt) the amount of precipitation decreases to 400 mm per year.
The water drains are oligotrophic. Only a few nutrients are bound in it, which allows only low organic production. This fact is due to the geomorphological conditions that the table mountain sandstone provides. The clear but acidic water often has pH values around 4.3. This is also indicated by the vegetation formations , which are often exhausted in sclerophylls and heathland .
Fauna / flora
The relatively acidic water of the Cape Fold Mountains does not allow for any biodiversity in the waters. Endemic carp fish , galaxies , two species of Cape bush fish and a number of representatives of the genus Barbus . Isolation processes have led to allopatric speciation in the genus Pseudobarbus . At times that predated the process of division of Gondwana, the sometimes endemic habitats for insects , arthropods , dragonflies , flying insects such as stone flies and amphibians such as ghost frogs developed in the Cape region .
Typical botany are sour grass plants such as cornices , Thurniaceae from the sweet grass family and Dicranaceae from the moss family . Furthermore, the vegetation is mountain fynbos dominated proteaceae , silver trees , soap tree plants , Asteraceae , celastraceae and fields of sugar bushes . In addition, in higher regions of the mountains, rooibos , larkspurs , rhombuses and orchids occur .
Individual evidence
- ↑ a b c d B.R. Allanson, Inland Waters of Southern Africa: An Ecological Perspective , Volume 64, pp. 51 ff.
- ↑ 84 Mountains with prominence of 1,500m (4,921 ft.) Or greater
- ↑ GEOLOGY OF THE CAPE PENINSULA ( Memento of the original from July 19, 2012 in the web archive archive.today ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ JJ Veevers, Chris Powell, Permian-Triassic Pangean Basins and Foldbelts Along the Panthalassan Margin of Gondwanaland , Issue 184
- ↑ Prof. Dr. Alfred Wegener, The emergence of the continents and oceans , 2nd completely revised edition. With 33 illustrations (1920)
- ↑ JJ Lambiase: The framework of African rifting during the Phanerozoic. in: Journal of African Earth Sciences (8) 1989, pp. 183-190
- ↑ D. ADELMANN, K. FIEDLER, Sedimentary development of the Upper and Lower Ecca Beaufort Groups (Karoo Supergroup) in the Laingsburg SubBasin (SW Karoo Basin, Cape Province / South Africa)
- ^ FW North: Colonial Mining Engineers Report on the Coalfield of the Stormbergen. Parliamentary Report of the Cape of Good Hope, G47., 1878
- ↑ DJ Cole, Evolution and development of the Karoo Basin , in: MJ De Wit, IGD Ransome, IGD (eds.): Inversion tectonics of the Cape Fold Belt, Karoo and Cretaceous Basins of Southern Africa: 109-115, Rotterdam (1992 )
- ^ A b Nick Norman, Gavin Whitefield: Geological Journeys . Cape Town (Struik Publishers) 2006, pp. 153-166 ISBN 1-77007-062-1
- ↑ Notes on folding lines
- ↑ Cederberg Wilderness Area (exemplary list of plants) ( Memento of the original from November 23, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
