Biological evidence for better appreciation of the Indian Gondwana

Abstract

The Gondwana sequences in India are located in intraplate graben or semi graben basins along Narmada-Son-Damodar, Son-Mahanadi and Pranhita-Godavari ancient fracture zones. The basal glacial tillite of these sequences as also their diverse geological similarities, specially the coal-bearing lower part, was well and uniformly understood very widely even beyond the frontiers of India in distant Africa, South America, Australia, Madagascar and Antarctica which are now separated by several thousand kilometers of intervening land, sea or oceanic distances. Obviously, it did not take many years for the Gondwana as a stratigraphic unit of super-order to receive wide acceptance through the length and breadth of the southern hemisphere. With refinement in stratigraphic terminology over the last several decades and growing information about the dissimilarities which were not so evident in the beginning, the usage of the term Gondwana inspite of such a spectacular and sound foundation as stratigraphic unit went into disuse in other Gondwanaland constituents in favour of local names while the term Gondwanaland as a supercontinent became firmly entrenched in global geological literature. Moreover, in view of the multidimensional nature of the Indian Gondwana stratigraphic units, viz., their physical, lithological, climatic, tectonic, stratigraphic, facies floral, faunal and other expressions added often to lack of their precise comprehension and usage in line with modern stratigraphic nomenclature there has crept in lot of misunderstanding, contradictions and confusions. An effort has been made to resolve problems concerning classification, definition, distribution, dating and correlation using biological evidence and geological information from the Indian Gondwana and coeval units.