Komati Gorge

Last updated August 30, 2019

Komati Gorge is a river valley in the Mpumalanga Province in central South Africa, which features vertical sandstone cliffs that provide habitat for a wide diversity of wildlife. Komati Gorge is located near the communities of Carolina and Machadodorp. The Komati River flows through the gorge and provides riparian cover for many species of flora and fauna, including several endemic endangered species and big game animals. The geology of the vertical cliffs of the gorge offer a diverse set of colourful mineralized exposures.

A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases a river flows into the ground and becomes dry at the end of its course without reaching another body of water. Small rivers can be referred to using names such as stream, creek, brook, rivulet, and rill. There are no official definitions for the generic term river as applied to geographic features, although in some countries or communities a stream is defined by its size. Many names for small rivers are specific to geographic location; examples are "run" in some parts of the United States, "burn" in Scotland and northeast England, and "beck" in northern England. Sometimes a river is defined as being larger than a creek, but not always: the language is vague.

Valley Low area between hills, often with a river running through it.

A valley is a low area between hills or mountains typically with a river running through it. In geology, a valley or dale is a depression that is longer than it is wide. The terms U-shaped and V-shaped are descriptive terms of geography to characterize the form of valleys. Most valleys belong to one of these two main types or a mixture of them, at least with respect to the cross section of the slopes or hillsides.

South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by 2,798 kilometres (1,739 mi) of coastline of Southern Africa stretching along the South Atlantic and Indian Oceans; to the north by the neighbouring countries of Namibia, Botswana, and Zimbabwe; and to the east and northeast by Mozambique and Eswatini (Swaziland); and it surrounds the enclaved country of Lesotho. South Africa is the largest country in Southern Africa and the 25th-largest country in the world by land area and, with over 57 million people, is the world's 24th-most populous nation. It is the southernmost country on the mainland of the Old World or the Eastern Hemisphere. About 80 percent of South Africans are of Bantu ancestry, divided among a variety of ethnic groups speaking different African languages, nine of which have official status. The remaining population consists of Africa's largest communities of European, Asian (Indian), and multiracial (Coloured) ancestry.

Geology

Within the Komati Gorge are exposures of the Kromberg Formation and upper Hooggenoeg Formation of the Onverwacht Series in which debris flows, turbidites, and thin gray chert units are exhibited.^[1] There are also exposures of black and white banded cherts interbedded with basalt flows representing eastern faces of Black Reef Chert. A banded iron formation is exposed in the bluffs.

Debris flows are geological phenomena in which water-laden masses of soil and fragmented rock rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form thick, muddy deposits on valley floors. They generally have bulk densities comparable to those of rock avalanches and other types of landslides, but owing to widespread sediment liquefaction caused by high pore-fluid pressures, they can flow almost as fluidly as water. Debris flows descending steep channels commonly attain speeds that surpass 10 m/s (36 km/h), although some large flows can reach speeds that are much greater. Debris flows with volumes ranging up to about 100,000 cubic meters occur frequently in mountainous regions worldwide. The largest prehistoric flows have had volumes exceeding 1 billion cubic meters. As a result of their high sediment concentrations and mobility, debris flows can be very destructive.

A turbidite is the geologic deposit of a turbidity current, which is a type of sediment gravity flow responsible for distributing vast amounts of clastic sediment into the deep ocean.

Chert A hard, fine-grained sedimentary rock composed of crystals of quartz (silica) that are very small

Chert is a hard, fine-grained sedimentary rock composed of crystals of quartz (silica) that are very small (microcrystalline or cryptocrystalline). Quartz (silica) is the mineral form of silicon dioxide (SiO₂). Chert is often of biological origin (organic) but may also occur inorganically as a chemical precipitate or a diagenetic replacement (e.g., petrified wood). Geologists use chert as a generic name for any type of microcrystalline or cryptocrystalline quartz.

Ecology

Komati Gorge western cliffs. Komatigorgecliffscmichaelhoganlowres.jpg — Komati Gorge western cliffs.

The Komati Gorge contains a great diversity of flora and fauna, including many large mammalian species. There are several discrete types of habitat present, including riparian zone, bluff habitat, thorn bushveld and highveld grassland. The river provides not only water for wildlife and aquatic vegetation, but also supports a robust riverine trout fishery. The bluffs support a very specialized ecosystem including vegetation adapted to the steep rocky vertical landform of the gorge sides.^[2] In addition there are favourable opportunities for bird habitat, providing more protection from certain predators; for example the threatened southern bald ibis inhabits these cliff habitats.

Biodiversity is the variety and variability of life on Earth. Biodiversity is typically a measure of variation at the genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near the equator, which is the result of the warm climate and high primary productivity. Biodiversity is not distributed evenly on Earth, and is richest in the tropics. These tropical forest ecosystems cover less than 10 percent of earth's surface, and contain about 90 percent of the world's species. Marine biodiversity is usually highest along coasts in the Western Pacific, where sea surface temperature is highest, and in the mid-latitudinal band in all oceans. There are latitudinal gradients in species diversity. Biodiversity generally tends to cluster in hotspots, and has been increasing through time, but will be likely to slow in the future.

Mammals are vertebrate animals constituting the class Mammalia, and characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex, fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles and birds, from which they diverged in the late Triassic, 201–227 million years ago. There are around 5,450 species of mammals. The largest orders are the rodents, bats and Soricomorpha. The next three are the Primates, the Cetartiodactyla, and the Carnivora.

In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined.

Mammal species include big game animals as well as smaller fauna; for example zebra and giraffe can be found on the bushveld. Eland, Impala and other bovids are numerous.

Zebras are several species of African equids united by their distinctive black-and-white striped coats. Their stripes come in different patterns, unique to each individual. They are generally social animals that live in small harems to large herds. Unlike their closest relatives, horses and donkeys, zebras have never been truly domesticated.

The giraffe (Giraffa) is an African even-toed ungulate mammal, the tallest living terrestrial animal and the largest ruminant. It is traditionally considered to be one species, Giraffa camelopardalis, with nine subspecies. However the existence of up to eight extant giraffe species have been described, based upon research into the mitochondrial and nuclear DNA, as well as morphological measurements of Giraffa. Seven other species are extinct, prehistoric species known from fossils.

Taurotragus is a genus of large antelopes of the African savanna, commonly known as elands. It contains two species: the common eland T. oryx and the giant eland T. derbianus.

Approximately three million years ago the underlying geological formations took shape in the Komati Gorge area, producing one of the Earth's rarest and most endangered ecosystems, the ancient grasslands of Africa. With increasing rainfall on the lowlands, an invasion of trees ensued, constituting the bushveld of the lowveld ecosystems present here.

An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment, interacting as a system. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the system through photosynthesis and is incorporated into plant tissue. By feeding on plants and on one-another, animals play an important role in the movement of matter and energy through the system. They also influence the quantity of plant and microbial biomass present. By breaking down dead organic matter, decomposers release carbon back to the atmosphere and facilitate nutrient cycling by converting nutrients stored in dead biomass back to a form that can be readily used by plants and other microbes.

Grasslands are areas where the vegetation is dominated by grasses (Poaceae); however, sedge (Cyperaceae) and rush (Juncaceae) families can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur naturally on all continents except Antarctica. Grasslands are found in most ecoregions of the Earth. For example, there are five terrestrial ecoregion classifications (subdivisions) of the temperate grasslands, savannas, and shrublands biome (ecosystem), which is one of eight terrestrial ecozones.

Access and condition

Access is from the north, via the towns of Carolina or Machadodorp, which towns are near the main highway leading to Johannesburg. Most of the Komati Gorge has been historically privately owned wilderness, with some ranching arriving in the latter half of the 20th century. Since the late 20th century there has been limited development of a lodge and a few country homes.

A highway is any public or private road or other public way on land. It is used for major roads, but also includes other public roads and public tracks: It is not an equivalent term to controlled-access highway, or a translation for autobahn, autoroute, etc.

Johannesburg is the largest city in South Africa and one of the 50 largest urban areas in the world. It is the provincial capital and largest city of Gauteng, which is the wealthiest province in South Africa. While Johannesburg is not one of South Africa's three capital cities, it is the seat of the Constitutional Court. The city is located in the mineral-rich Witwatersrand range of hills and is the centre of large-scale gold and diamond trade.

A ranch is an area of land, including various structures, given primarily to the practice of ranching, the practice of raising grazing livestock such as cattle or sheep for meat or wool. The word most often applies to livestock-raising operations in Mexico, the Western United States and Western Canada, though there are ranches in other areas. People who own or operate a ranch are called ranchers, cattlemen, or stockgrowers. Ranching is also a method used to raise less common livestock such as elk, American bison or even ostrich, emu, and alpaca.

As of 2006, visitation to the Komati Gorge is not intense, although there has been a recent case of geo-vandalism in the form of illegal drilling of some of the rock outcrops.^[3] Geo-vandalism is a term meaning defacing, alteration or drilling in significant rock formations either for unauthorised fossil collection, mineral exploration or malicious destruction.

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The Sacramento National Wildlife Refuge Complex is part of the United States system of National Wildlife Refuges (NWR). It is located in northern California, in the valley of the Sacramento River.

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References

External links

Southern Bald Ibis sightings at Komati Gorge

Coordinates: 25°52′07″S30°18′26″E / 25.86861°S 30.30722°E / -25.86861; 30.30722

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[1] NASA Astrobiology Institute Achean Surface Processes: South Africa

[2] C. Michael Hogan and Amy Gregory, Ecology of Komati Gorge, Lumina Technologies, July 22, 2006 Archived May 28, 2010, at the Wayback Machine

[3] Geo-vandalism at Komati Gorge