Certain parts of the ground surface of South Africa are prone to sudden, catastrophic collapse which may lead to death, injury or structural damage. Such features are known as sinkholes and in this part of the world sinkholes occur in areas underlain by dolomite rock. Dolomite rock comprises a system of discontinuities (fractures, joints and faults) which act as preferential solution passages. Although dolomite rock is relatively impervious and insoluble in pure water, rainwater which has become charged with carbon dioxide in its passage through the atmosphere and the soil flows along these discontinuity passages and slowly acts to dissolve this rock type.
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