GONDWANALAND. This name, derived from Gond wana, a district of Central India, was given by Suss to the inferred Palaeozoic continent, that at its greatest extension spanned the South Atlantic and Indian oceans—incidentally including Sclater's Lemuria linking India, Madagascar, and Africa, and Ihering's Arch-hellenis uniting Africa with Brazil. It embraced all (except north-west) Africa, Madagascar, peninsular India, Australia, Tas mania, Antarctica, Falklands, and all South America except the extreme west and north-west. Its unstable margins were between the Devonian and Jurassic, intermittently and widely transgressed by the oceans ; the sea bounding it on the north, wherein deposition went on continuously down to the Tertiary, being called the "Tethys"—with the Mediterranean as a remnant.
Sedimentation upon Gondwanaland itself was predominantly of "continental" type, the widespread strata—Gondwana beds— being often coal-bearing and frequently still horizontal. Highly folded banded ironstones and jaspilites characterise the Proter ozoic. Noteworthy are those deposits betraying glacial conditions during several epochs—in the late pre-Cambrian, early Devonian and especially late Carboniferous (so-called Permian or Permo carboniferous), the last-named occupying enormous stretches with in the west and south-east of Australia, Tasmania, (possibly New Zealand), peninsular India (and the Salt Range), southern Mada gascar, South Africa (possibly the Congo), Falklands, south-east ern Brazil, Uruguay, Paraguay, and central and western Argentina. Those morainic deposits are regarded as the products of continen tal ice-caps of vast extent and huge thickness, that developed over relatively low-lying ground, moving outwards over distances meas urable in hundreds of miles and passing into the ocean in places, as indicated by beds with marine fossils. This intense refrigera tion (with milder inter-glacial periods) began in the mid-Carbonif erous in New South Wales and only ended there in the Permian, attaining its maximum throughout the regions cited towards the close of the Carboniferous.
The causes are obscure and much debated. The boulder-beds with striated erratics and underlying grooved rock-surfaces dis close the ice-movement, which was away from the South Pole except in Africa. The succeeding Permian sediments contain the workable coals of the Southern hemisphere. The Triassic is sig nalled by diastrophism and transgression; and later by widespread aridity, as in Europe. In the early Jurassic, floods of basalt (some times rhyolite) terminated sedimentation and the strata beneath were riddled with intrusive dolerite in South Africa, Tasmania, Antarctica, and Brazil.
The breaking up of Gondwanaland dates from that time, though not accomplished until late in the Cretaceous—a process currently ascribed to the foundering of segments of the continent or of nar row "land bridges." Under Wegener's "Displacement Hypothesis," however, the continent is supposed to have fractured and the crustal blocks, floating on a liquefied basic substratum (basalt), to have drifted apart, pushing up before them the marine sedi ments bordering Gondwanaland, and elevating them as the Ter tiary folded chains of the Andes, Morocco, Alps, Iranian chains, Himalayas, New Zealand, which encircle its relics. Magma was squeezed into or erupted through the rising arches, as in the Andes. The Great Rift Valley of Africa with its prolonged volcanicity and the lavas of the Deccan (India) and Abyssinia bespeak zones of tension in the crust.
Distinctive of the Gondwana beds is the "Southern" or Glossop teris Flora—with its few "Northern" Carboniferous elements in South America and South Africa that survived the intense glacia tion—ousted in late Triassic times by the Thinn f eldia Flora, with return to floral uniformity throughout the globe in the Jurassic. Reptilia and amphibia belonging to the orders Anomodontia, Ther ocephalia, Therodontia, and Saurischia characterise the Permo Triassic, especially that of the Karroo (spreading partly into Rus sia), the Triassic Cynodontia being apparently ancestral to the Mammalia. Post-Cretaceous vertebrate evolution followed diverg ing lines in the fragments of Gondwanaland, producing the Eden tata of Patagonia, Proboscidea of Africa and Asia, and Monotre mata of Australasia. As noted by Blanford, the distribution and affinities of their existing faunas point to the former continental unity of these areas. For example the lemurs of Africa, Madagas car and India, manati of West Africa and the Amazon, fresh water fishes, birds of Strutliio-type, blind snakes, geckos, scorpions, decapod Crustacea, Helicidae, isopod Phreatoicus and oligochete Phreodrillidae, could not have crossed the oceans. Similar evi dence is obtainable from the present floras and the actuality of this former continent appears unquestionable. (A. L. DU T.)