Karst Landscapes
1. Introduction
Karst limestone is the technical term for a highly distinctive form of weathered limestone dominated by rounded conelike hills or steep or vertical sided ‘towers’. Although fengling (cone) and fengcong (tower) karst are different in appearance, they are sequential stages of a long process of formation. Fengcong towers developed from fengling cones that were steepened by water table undercutting (Pelling, 2008:50).
This assignment will pay attention to the following aspects on the topic of karst geomorphology in South Africa. First by explaining the processes at work in karts (limestone) areas, then on why are such areas potentially dangerous, and finally how should these areas be managed in South Africa. The assignment will be finished with a conclusion.
2. The complex process
The entire process requires three key elements to coexist over millions of years:
• a very deep layer of high-quality limestone
• continuous warm wet weather
• slow, steady tectonic uplift – around a millimetre a year
The only area in the world where these requirements were fully satisfied was Southeast Asia, and particularly in what is now the Guangxi province of southern China and in Vietnam (Henderson, 2004:110).
According to Ziervogel (2007:83) the layers of sediment from which the limestone is formed is laid down in horizontal layers, or strata. Steady tectonic pressure from underneath causes the limestone strata to fracture. If the uplift is completely even and the limestone pure and free from impurities, the bedrock fractures along regular lines at right angles, creating the familiar ‘limestone pavements’ found in cool latitudes.
Ziervogel (2007:85) also says that as the limestone rise, the fractures becomes hair cracks, wide enough for moisture to enter. Rain falls through the atmosphere, picking up carbon dioxide, which dissolves in the droplets. When the rain hits the ground, it percolates through the soil to form a weak solution of carbonic acid
Karst limestone is the technical term for a highly distinctive form of weathered limestone dominated by rounded conelike hills or steep or vertical sided ‘towers’. Although fengling (cone) and fengcong (tower) karst are different in appearance, they are sequential stages of a long process of formation. Fengcong towers developed from fengling cones that were steepened by water table undercutting (Pelling, 2008:50).
This assignment will pay attention to the following aspects on the topic of karst geomorphology in South Africa. First by explaining the processes at work in karts (limestone) areas, then on why are such areas potentially dangerous, and finally how should these areas be managed in South Africa. The assignment will be finished with a conclusion.
2. The complex process
The entire process requires three key elements to coexist over millions of years:
• a very deep layer of high-quality limestone
• continuous warm wet weather
• slow, steady tectonic uplift – around a millimetre a year
The only area in the world where these requirements were fully satisfied was Southeast Asia, and particularly in what is now the Guangxi province of southern China and in Vietnam (Henderson, 2004:110).
According to Ziervogel (2007:83) the layers of sediment from which the limestone is formed is laid down in horizontal layers, or strata. Steady tectonic pressure from underneath causes the limestone strata to fracture. If the uplift is completely even and the limestone pure and free from impurities, the bedrock fractures along regular lines at right angles, creating the familiar ‘limestone pavements’ found in cool latitudes.
Ziervogel (2007:85) also says that as the limestone rise, the fractures becomes hair cracks, wide enough for moisture to enter. Rain falls through the atmosphere, picking up carbon dioxide, which dissolves in the droplets. When the rain hits the ground, it percolates through the soil to form a weak solution of carbonic acid