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Heuningnes: Catchment Characteristics |
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The development of the area took place during the Tertiary and Recent (that is, during the past 70 million years) periods, beginning with prolonged erosion, after which the ocean covered most of the area underlain by Bredasdorp Beds which consist of calcified dune sand. These occur along the whole coast up to the Potberg Mountain in a band varying from three to twenty kilometres in width. During the Miocene (26 to 7 million years ago) the ocean began to retreat and on this wavecut platform the Bredasdorp Beds were left as inshore deposits. The beach sand was blown up into dunes that crossed the former extension of the ocean. Subsequently the sea level rose again and a platform was cut over Bredasdorp and older formations. As the sea retreated again, the beach sand was blown up into dunes locally on this younger marine terrace. Still later the sea level sank further, due to worldwide glaciation and another terrace was formed. Its maximum height is 7 m and it is preserved only in patches along the coast. (Ref 2) |
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Greater resistance to weathering processes has left the Table Mountain Sandstone as the most prominent feature in the landscape, forming high ground and mountain ranges. The less resistant shales have weathered resulting in the round hilly nature of the Bokkeveld shales in the undulating country in the upper reaches of the Heuningnes catchment. (Ref 2) |
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