The facts and fictions of the Gondana Concept

Abstract

Wegner did not envisage that Gondwanaland was an independent continent. This concept was introduced earlier but concretised by Du Toit. His Permian ice-cap covered almost the entire supercontinent. Ahmad, however, pointed out that the ice-cap at no stage was exceptionally large. Du Toit was not aware of the glacial deposits in Arabia or Tibet, and his ice-cap would have to be enlarged considerably if it was to form deposits in these areas, particularly the latter as well. All evidence goes to suggest that Tibet was not separated from India in the Permo-Triassic and the suture zone concept is not valid. These Tibetan glacial deposits carry Glossopteris flora and Stepanoviella and Eurydesma fauna as typical Gondwana forms. The deposits reach upto Kun Lun mountains.

The Himalayan region was separated from the peninsular basin and was part of the southern margin of an epicontinental Tethys. The ice-cap did not reach this area. However, Himalayan diamictites, as also those of Tibetan should be older than the peninsular and a Carboniferous age assigned to them by Chinese geologists may be valid.

The Gondwana concept envisaged glacial deposits overlain by freshwater sediments. This seemed to apply to peninsular India. Western Australia, South Africa, etc. But of late marine incursions have been reported from India and South Africa leaving, perhaps, only Antarctica where it could truly be applied today. The ice-cap covered peninsular India and peneplained it so that after it receded, the area was significantly down warped and this resulted in marine incursions. Umaria’s access to the sea was obviously to the southeast underneath the ice-cap and hence it could not carry fauna older than that of Manendragarh, Rajhara, too was perhaps an extension of this sea, although it could have been independent.