Gondwana Sentence Examples
The Gondwana series is economically of great importance.
The formation of this and of the other great mountain chains of central Asia resulted in the isolation of portions of the former central sea; and the same forces finally led to the elevation of the whole region and the union of the old continents of Angara and Gondwana.
The first of these is mentioned in 1398, when Narsingh Rai, raja of Kherla, is said by Ferishta to have ruled all the hills of Gondwana.
The Gondwana beds contain fossils which are of very great interest.
In large part these consist of plants which grew near the margins of the old rivers, and which were carried down by floods, and deposited in the alluvial plains, deltas and estuarine areas of the old Gondwana period.Advertisement
But even within the limits of the Lower Gondwana series there are great diversities of vegetation, three distinct floras occurring in the three great divisions of that formation.
In many respects the flora of the highest of these three divisions (the Panchet group) is more nearly related to that of the Upper Gondwanas than it is to the other Lower Gondwana floras.
Although during the Gondwana period the flora of India differed greatly from that of Europe, it was strikingly similar to the contemporaneous floras of South America, South Africa and Australia.
One of the most interesting facts in the history of the Gondwana series is the occurrence near the base (in the Talchir group) of large striated boulders in a fine mud or silt, the boulders in one place resting upon rock (of Vindhyan age) which is also striated.
The beds there are lower in the series than those of the Raniganj field; they belong to the upper part of the Talchir group, the lowest of the Gondwana series.Advertisement
Contemporaneously with the formation of the upper part of the Gondwana series marine deposits of Jurassic age were laid down in Cutch.
Vertebraria and Phyllotheca, plants characteristic of the Indian Gondwana series, have been recorded in Sarawak; and marine forms, similar to those of the lower part of the Australian Carboniferous system, are stated to occur in the limestone of north Borneo.
Compared with the Gondwana coal of the peninsula of India the Tertiary coal seams of Assam are remarkable for their purity and their extraordinary thickness.
In the peninsula, however, no marine fossils have yet been found of earlier date than J urassic and Cretaceous, and these are confined to the neighbourhood of the coasts; the principal fossiliferous deposits are the plantbearing beds of the Gondwana series, and there can he no doubt that, at least since the Carboniferous period, nearly the whole of the Peninsula has been land.
Over the surface of the gneissic rocks are scattered numerous basins of Gondwana beds.Advertisement
In the Rajmahal Hills basaltic lava flows are interbedded with the Gondwana deposits, and in the Karharbari coalfield the Gondwana beds are traversed by dikes of mica-peridotite and basalt, which are supposed to be of the same age as the Rajmahal lavas.
Several of the plants are identical with forms which occur in the upper portion of the Gondwana system.
In late Carboniferous times Africa and India were undoubtedly united to form a large continent, called by Suess Gondwana Land.
The interior of the African portion of Gondwana Land was occupied by several large lakes in which an immense thickness - amounting to over 18,000 ft.
It was doubtless connected with the disruption of Gondwana Land, since it is known that this great alteration of geographical outline commenced in Jurassic times.Advertisement
The breaking up of Gondwana Land is usually considered to have been caused by a series of blocks of country being let down by faulting with the consequent formation of the Indian Ocean.
In India the same flora occurs in a thick series of fresh-water sediments, known as the Lower Gondwana system, including basal boulder-beds like those of Australia.
There can be little doubt that the Indian Lower Gondwana rocks, in which the boulder-beds and the Glossopteris flora occur, must be regarded as belonging to a vast continental area of which remnants are preserved in Australia, South Africa and South America.
This continental area has been described as " Gondwana Land," a tract of enormous extent occupying an area, part of which has since given place to a southern ocean, while detached masses persist as portions of more modern continents, which have enabled us to read in their fossil plants and ice-scratched boulders the records of a lost continent in which the Mesozoic vegetation of the northern hemisphere had its birth.
Amalitzky found in beds of Upper Permian age in the province of Vologda (Russia) (Map A, V.) species of Glossopteris and Naeggerathiopsis typical members of the Glossopteris flora, associated with species of the ferns Taeniopteris, Callipteris and Sphenopteris, a striking instance of a commingling in the far north of the northern hemisphere Permian species with migrants from " Gondwana Land."Advertisement
These post-Permian floras, as represented by the Upper Gondwana beds of India and corresponding strata in Australia, South Africa, and South America, differ but slightly from the northern floras, and point to a uniformity in the Rhaetic and Jurassic vegetation which is in contrast to the existence of two botanical provinces during the latter part of the Palaeozoic period.
The existence of Upper Gondwana plants, resembling Jurassic species from the Rajmahal beds of India, has been demonstrated in the Argentine by Dr Kurtz.
Of other Equisetales there are Schizoneura and Phyllotheca; the former first appears in Lower Gondwana rocks as a member of the Glossopteris flora, migrating at a later epoch into Europe, where it is represented by a Triassic species.
The latter genus ranges from Upper Carboniferous to Jurassic rocks; it occurs in India, Australia, and elsewhere in the " Gondwana Land " vegetation, as well as in Palaeozoic rocks of Asia Minor, in Permian rocks of Siberia, and in Jurassic plant-beds of Italy.
An example of an Indian Cycadean stem from Upper Gondwana rocks is represented in fig.
Williamsonia occurs in the Upper Gondwana rocks of India; it is recorded also from strata ranging from the Rhaetic to the Lower Cretaceous period in England, Portugal, Sweden, Bornholm, Greenland, Italy and North America.
The difference between the Glossopteris flora and those which have left traces in the Upper Gondwana rocks of India, in the Wianamatta and Hawkesbury beds of Australia, and in the Stormberg series of South Africa is much less marked than that between the PermoCarboniferous flora of the northern hemisphere and the succeeding Mesozoic vegetation.
The location of mantle plumes during the initial stages of Gondwana break up.
It is thought the pines populated the ancient supercontinent Gondwana when dinosaurs walked the Earth.
In the same way the entire absence of any marine fossils in the peninsula of India, excepting near its borders, and the presence of the terrestrial and freshwater deposits of the Gondwana series, representing the whole of the geological scale from the top of the Carboniferous to the top of the Jurassic, show that this region also has been land since the Carboniferous period.
Chhindwara formed part of the dominions of the ancient Gond dynasty of Chhindwara and Nagpur, whose seat was at Deogarh until, in the 18th century, it was removed by Chand Sultan, son of Bakht Buland (founder of the short-lived greatness of the dynasty, and of the city of Nagpur) to Nagpur (see Gondwana and Nagpuu) .
During the Jurassic period, 180 million years ago, it formed the core of a supercontinent called Gondwana.
It was replaced by the Glossopteris flora which is assumed to have originated in a vast continental area (Gondwana land), of which remnants remain in South America, South Africa and Australia.
Both were in turn replaced by the Lower Mesozoic flora, which again is thought to have had its birth in the hypothetical Gondwana land, and in which Gymnosperms played the leading part formerly taken by vascular Cryptogams. The abundance of Cycadean plants is one of its most striking features.
Dvina, Glossopteris, Noeggerathiopsis and other ferns characteristic of the Indian Gondwana beds have been found; and with these are numerous remains of reptiles similar to those which occur in the Indian deposits.
By the people of northern India the country was known as Gondwana, after the savage tribes of Gonds by whom it was inhabited.
Meanwhile the other independent principalities of Gondwana had in turn succumbed.
According to Ferishta, the Persian historian, these kingdoms engrossed in 1398 all the hills of Gondwana and adjacent countries, and were of great wealth and power.
Suess outlined the ancient relations of Africa and Asia through his " Gondwana Land," a land mass practically identical with the " Lemuria " of zoologists.
The plant beds occur at several horizons, and among the remains which have been found in them are several forms which occur also in the Gondwana beds of India.
There can be no doubt that the series as a whole is the equivalent of the Gondwana system, and when the country has been more closely examined the association of marine fossils with Gondwana plants will be of the greatest value in determining the precise homotaxis of the Indian deposits.
The Gondwana series is in many respects the most interesting and important series of the Indian Peninsula.
The lowest Gondwanas are very constant in character, wherever they are found; the upper members of the lower division show more variation, and this divergence of character in different districts becomes more marked in the Upper Gondwana series.