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Geology of KwaZulu-Natal |
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Drakensberg & |
Lebombo group | |||
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Dramatic outpourings of lava spread across much of Gondwana about 180 million years ago heralding the start of Gondwana breakup. Remnants of these once extensive lavas now form the Lesotho highlands and Lebombo mountains.
A 1.5 kilometre thick accumulation of Jurassic age basalt flows can be seen along the Drakensberg Escarpment. The magma (molten rock) made its way to the surface along a complex system of fractures. |
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Crystallisation of magma within these fractures formed dolerite sills and dykes.
Sills are horizontal intrusions of igneous rock. Dolerite sills are common throughout inland KZN in sedimentary rocks of the Karoo Supergroup. |
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Move your mouse over the picture to see the boundary between the basalt lava and the dolerite dyke. |
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Move your mouse over the schematic diagram to see where the sills and dykes are. |
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Amphitheatre, Drakensberg Mountains |
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The sills often form flat areas and weather to form a very dark red soil. The sill may also form resistant cliffs such as at Howick Falls. | |||
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Howick Falls |
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The final volcanic event produced rhyolite lava which now forms the Lebombo mountains. These volcanic events were followed by uplift and faulting that eventually separated Africa and Antarctica.
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Lebombo Mountain south of Jozini |
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last updated:
26 Sep 2006
© School of Geological Sciences, University of KwaZulu-Natal
The website was designed and compiled by Dr. G. Whitmore, Ms D. Meth and Dr. R. Uken (modified by T. Reinhardt.)