Throughout the world, you can see examples of Karst landscapes. Many Karst terrains are now tourism hotspots providing beautiful canyons for rafting or canoeing while others offer sports enthusiasts with the opportunity to discover an underground world with a unique ecosystem. Geoscience Australia estimates that up to 15 per cent of Australia consists of karst landscapes with only four per cent seen at the ground surface.
Beautiful landscapes in Australia that have been produced by Karst process include;
The intricate process of creating a karst landscape begins when water and sedimentary rock which is capable of being dissolved by surface water or groundwater is either physically or chemically eroded away.
Examples of this type of sedimentary rock include chalk, gypsum and limestone. Limestone is the most common sedimentary rock is formed from the compaction of dead shells and skeletal Molluscs which contain calcium carbonate, making it soluble.
This chemical erosion first starts when rainwater mixes with CO2 it makes an acid solution that seeps into the soil picking up more CO2, eventually reaching bedrock. However, if the acidic rain that has seeped into the cracks and crevices of the bedrock and if the rock is soluble, chemical erosion will start to occur, hollowing it out forming magnificent subterranean caves that are trademark karst environments.
Other tell-tale signs of a Karst landscape include sinkholes. These are formed from the washout of subterranean material or decaying buried organic material and are formed from the surface down called suffosion. Large particles of clay, sand and gravel are dissolved over time and washed down into a network of fractures and crevices in the underlying bedrock forming a cavity as result of the loss of subsurface support and eventually collapses in on itself.
Another karst terrain which is much more sensitive to man-induced effects is called a depression or in some cases land subsidence resulting from groundwater extraction. The water below ground is helping to keep the surface soil in place, lowering the water table can remove this support. If water is withdrawn from the ground at a faster rate than it is replenished, it can result in a depression or even a sinkhole.
Although the karst process sculpts beautiful landscapes, they are incredibly vulnerable to groundwater pollution. Just like rainwater, pollutants can easily pass through sedimentary rock. Surface runoff enters the network of underground fractures and crevices bypassing the natural filtration meaning the opportunity for contaminants to still be present is significantly increased.
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