Dwyka Group

Based on stratigraphic position, lithostratigraphic correlation and palynological analyses, these lowermost Karoo strata range between the Late Carboniferous (Pennsylvanian) to Early Permian in age.

[1][2][3][4] At the commencement of the deposition of the Dwyka Group, it is thought that the development of the Karoo supergroup foreland system had begun approximately 30 million years prior.

The continuation of the orogenic pulses from the growing Gondwanides mountain chain and associated subduction created accommodation space for sedimentation in the Karoo Basin which ran along an east to west trending foreland trough.

The result was the development of the Permo-Carboniferous glacial environment where massive ice sheets entombed the early Karoo Basin in the surrounding highlands and permanent, floating glaciers in the lowlands.

[5][6][7][8][9][10] The geological formations of the Dwyka Group are restricted to the edges of the Karoo Basin and achieve their greatest thickness in its southern deposits at approximately 800 m, progressively thinning out towards the north.

[24][25] The cold, glacial environment that the sedimentary rocks of the Dwyka Group were deposited in was not conducive for high plant diversity.

Caption: 1-South-America 2-Africa; 3-India; 4-Australia; 5-Antarctica; 6-Fossil remains of Cynognathus, a Triassic land reptile, approximately 3m long; 7- Fossil remains of the freshwater reptile Mesosaurus; 8-Fossil of the fern Glossopteris found in all of the southern continents show that they were once joined; 9-Fossil evidence of the Triassic land reptile Lystrosaurus
Caption: 1-South-America 2-Africa; 3-India; 4-Australia; 5-Antarctica; 6-Fossil remains of Cynognathus, a Triassic land reptile, approximately 3m long; 7- Fossil remains of the freshwater reptile Mesosaurus; 8-Fossil of the fern Glossopteris found in all of the southern continents show that they were once joined; 9-Fossil evidence of the Triassic land reptile Lystrosaurus
Greenish laminated siltstones of the Elandsvlei Fm, Dwyka Group, near Laingsburg, RSA, containing a solitary pebble which was apparently a dropstone, with thinned laminae draped over the top.