Page:Encyclopædia Britannica, Ninth Edition, v. 12.djvu/761

737 GEOGRAPHY.] INDIA 7o7 dar mj Id. .1 lar more the cycads, being more numerous than the ferns, whilst the Eyuisetacece are but sparingly found. 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 P.anchet group) is more nearly related to that of the Upper Gondwanas than it is to the other Lower Gondwana floras. One of the most interesting facts in the history of the Gondwana series is the occurrence near the base (in the Talcher 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. There seems good reason for believing that these beds are the result of ice- action. They probably nearly coincide in age with the Permian beds of Western Europe, in which Professor Ramsay long since discovered evidence of glaciation. But the remarkable fact is that this old ice-action occurred within the tropics, and probably at no very great height above the sea. The Ddmodar series, the middle division of the Lower Gondwanas, is the chief source of coal in Peninsular India, yielding more of that mineral than all other formations taken together. The Karharbari group is the only other coal-bearing formation of any value. The Damodars are 8400 feet thick in theTlaniganj coal-field, and about 10,000 feet thick in the Sutpura basin. They consist of three divisions ; coal occurs in the upper and lower, ironstone (without coal) in the middle division. The Raniganj coal field is the most important in India. So far as is yet known, it covers an area of about 500 square miles, extending about 18 miles from north to south and about 39 miles from east to west ; but it extends further to the east under the laterite and alluvium. It is traversed by the Ddmodar river, along which run the road from Calcutta to Benares and the East Indian Railway. From its situation and im portance this coal-field is better known than any other in India. Much has been learnt concerning it since the last examination by the Geological Survey, and our remarks are in great part based on recent reports by Mr II. Bauerman. The upper or Raniganj series (stated by the Geological Survey to be 5000 feet thick) contains eleven seams, having a total thickness of 120 feet, in the eastern district, and thirteen seams, 100 feet thick, in the western district. The average thickness of the seams worked is from 12 to 18 feet, but occasionally a seam acquires a great thickness 20 to 80 feet. The lower or Barakhar series (2000 feet thick) contains four seams, of a total thickness of 69 feet. Compared with English coals those of this coal-field are of but poor quality ; they contain much ash, and are generally non-coking. The seams of the lower series are the best, and some of these at Sdnktoria, near the Barakhar river, are fairly good for coke and gas. The best coal in India is in the small coal-field at Karharbari. The beds there are lower in the series than those of the RAniganj field ; they belong to the upper part of the Talcher group, the lowest of the Gondwana series. The coal-bearing beds cover an area of only about 11 square miles ; there are three seams, varying from 9 to 33 feet thick. The lowest seam is the best, and this is as good as English steam coal. This coalfield, now largely worked, is the property of the East Indian Railway, which is thus supplied with fuel at a cheaper rate than any other railway in the world. Indian coal usually contains phosphoric acid; which greatly lessens its value for iron-smelting. The Damodar series, which, as we have seen, is the chief source of coal in India, is also one of the most important sources of iron. The ore occurs in the middle division, coal in the highest and lowest. The ore is partly a clay ironstone, like that occurring in the Coal-measures of England, partly an oxide of iron or haematite. It generally contains phosphorus, which prevents its use in the pre paration of the finer qualities of steel. A similar difficulty attends the use of the Cleveland ore of North Yorkshire. Experiments have been in progress for years in search of a process which shall, in an economical manner, obtain iron from Cleveland ore free from phosphorus, latterly, it is hoped, with some success. If this be so, India will be a great gainer. Excellent iron-ore occurs in the Meta- morphic rocks south of the Ddmodar river. Laterite (see below) is sometimes used as ore. It is very earthy and of a low percentage ; but it contains only a comparatively small proportion of phosphorus. The want of limestone for flux, within easy reach, is generally a great drawback as regards iron-smelting in India. Kaukar or ghutin (concretionary carbonate of lime) is collected for this purpose from the river beds and alluvial deposits. It sometimes contains as much as 70 percent, of carbonate of lime; but generally the amount is much less and the fluxing value proportionally diminished. The real difficulty in India is to find the ore, the fuel, and the flux in sufficiently close proximity to yield a profit. The enormous mass of basaltic rock known as the Deccan Deccan trap is of great importance in the geological structure of trap, the Indian Peninsula. It now covers an area of about 200,000 square miles, and probably formerly extended over a much wider area. Where thickest, the traps are at least 6000 feet thick. They form the most striking physical features of the country, many of the most promi nent hill ranges being the denuded edges of the basaltic flows. The great volcanic outbursts which produced this trap commenced in the Cretaceous period and lasted on into the Eocene period. Laterite is a ferruginous and argillaceous rock, varying Laterite. from 30 to 200 feet thick, which often occurs over the trap area, but is also found in other districts. As a rule it makes rather barren land ; it is highly porous, and the rain rapidly sinks into it. Laterite may be roughly divided into two kinds, high-level and low-level laterites. The former, which covers a large area of the high basaltic plains, is believed by Mr R. B. Foote to be very fre quently the product of decomposition of the trap, and to have been thus formed in the place in which it is now found. Sometimes the high-level laterite overlies gneiss or other rocks ; and in these cases it has probably been transported. The low-level laterite is generally more sandy in character, and is often associated with gravels. In most cases this has clearly been carried down to its present position, probably largely by subaerial action, aided by rains and streams. Possibly in some cases it has been spread out along the coasts by marine action. The low-level laterite fringes the coast of the Peninsular more or less from near Bombay on the west and Orissa on the east to Cape Comorin. It is not continuous throughout these districts ; and it is of very varying width and eleva tion. The age of the high-level laterite is unknown. Its formation probably extended throughout a long period of time, much of which must be of very ancient date ; for the laterite, together with the underlying basalt, has suffered extensive denudation. The mercantile aspects of the coal, iron, and other mineral products of India will be fully treated of under a subse quent section (pp. 764-66). The geologist comes in this matter to the same conclusion as the economist, viz., that the mineral wealth of India, as represented by its precious stones, was the product of forced labour, and that the search for them in our days can scarcely repay the working expenses. fl or the above section on Geology we arc indebted to Mr W. Tojiley of the Eng lish Geological Survey.) XII. 01