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Geology of KwaZulu-Natal |
| Ecca Group - drifting to warmer latitudes | ||
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As Gondwana moved north towards the equator, thick clay and silt
beds were laid down in a large sea that occupied the Karoo basin.
These sediments now form shales of the Pietermaritzburg Formation.
The shales are easily weathered and often pesent slope
stability problems.
Overlying the shale is a is a thick sequence dominated by light grey sandstones, called the Vryheid Formation. These sandstones were deposited along ancient sandy shorelines behind which lay vast swamplands with numerous Glossopteris plants.
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Glossopteris leafs from the Ecca group (near Cedara, KwaZulu-Natal). The original leafs have been oxidised and replaced by iron oxide. Move your mouse over the picture to see a detailed Glossopteris leaf |
Distribution of Lystrosaurus and Glossoperis fossils |
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Burial of vegetation in the swamps eventually formed coal which is mined in the Vryheid area.
Close examination of the sandstones reveals numerous fossilised burrows formed by ancient soft bodied animals. These structures are similar to those formed by sand-burrowing crustaceans today. |
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Ecca shale is typically dark-coloured as they are carbon-rich due to the high vegetation content of the original sediments. Fine bedding or laminations may also be noted, and the shales tend to easily crumbled. |
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last updated:
29 Mar 2007
© 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.)