Cᵉ siècle av. J.-C.
Southern Africa and parts of Africa
Traduction non disponible · Original (anglais) · français indisponible
The Karroo Supergroup is an extensive succession of continental sedimentary rocks deposited from the later Carboniferous to the early Jurassic. Its fullest development lies in South Africa’s Karoo basin, where more than 7,000 metres of sediment accumulated. The sequence records major environmental changes, from glaciation through swampy conditions to increasingly arid landscapes, and preserves abundant plant and vertebrate fossils as well as important coal deposits.
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Le récit
The Karroo Supergroup developed after an intense glaciation in southern Africa and accumulated within a subsiding basin in the geographical area known as the Karoo. More than 7,000 metres of sediment were deposited in its maximum development in South Africa. Although the complete succession is best exposed in its type area, equivalent beds extend widely across Africa and also occur in Madagascar.
The succession spans the later Carboniferous to the early Jurassic and is divided in South Africa into four principal groups: Dwyka, Ecca, Beaufort, and Stormberg. The Dwyka is largely glacial tillite, while the Ecca consists mainly of dark shales and grey sandstones. Ecca beds contain Glossopteris plant remains and extensive coal deposits, especially in South Africa and Zimbabwe.
The Beaufort Group records swampy environments subject to desiccation and flooding. Its abundant vertebrate fossils include amphibians and, especially, reptiles that become increasingly mammal-like in higher layers. Two of the earliest true mammals known come from the Stormberg Group in Lesotho and are assigned an uppermost Triassic age.
The Stormberg Group shows a progressive shift toward desert conditions and ends with the eruption of up to 1,000 metres of basaltic lavas. These Stormberg or Drakensberg volcanics now form a protective cap on the highlands of Lesotho. Taken as a whole, the Karroo succession preserves a major environmental sequence from glaciation to warm swamps and finally near-desert conditions.
Cᵉ siècle av. J.-C.
Southern Africa and parts of Africa
Traduction non disponible · Original (anglais) · français indisponible
The Karroo Supergroup is an extensive succession of continental sedimentary rocks deposited from the later Carboniferous to the early Jurassic. Its fullest development lies in South Africa’s Karoo basin, where more than 7,000 metres of sediment accumulated. The sequence records major environmental changes, from glaciation through swampy conditions to increasingly arid landscapes, and preserves abundant plant and vertebrate fossils as well as important coal deposits.
Poursuivre l’exploration
Le récit
The Karroo Supergroup developed after an intense glaciation in southern Africa and accumulated within a subsiding basin in the geographical area known as the Karoo. More than 7,000 metres of sediment were deposited in its maximum development in South Africa. Although the complete succession is best exposed in its type area, equivalent beds extend widely across Africa and also occur in Madagascar.
The succession spans the later Carboniferous to the early Jurassic and is divided in South Africa into four principal groups: Dwyka, Ecca, Beaufort, and Stormberg. The Dwyka is largely glacial tillite, while the Ecca consists mainly of dark shales and grey sandstones. Ecca beds contain Glossopteris plant remains and extensive coal deposits, especially in South Africa and Zimbabwe.
The Beaufort Group records swampy environments subject to desiccation and flooding. Its abundant vertebrate fossils include amphibians and, especially, reptiles that become increasingly mammal-like in higher layers. Two of the earliest true mammals known come from the Stormberg Group in Lesotho and are assigned an uppermost Triassic age.
The Stormberg Group shows a progressive shift toward desert conditions and ends with the eruption of up to 1,000 metres of basaltic lavas. These Stormberg or Drakensberg volcanics now form a protective cap on the highlands of Lesotho. Taken as a whole, the Karroo succession preserves a major environmental sequence from glaciation to warm swamps and finally near-desert conditions.