ms of the Ganges. This tract is famous under the rious parts of this delta great accumulations, or Having in the precedin It is the effects of rivers in fo is will allow, it is pro student with an accou ents, which have been m id matter water is capa proper, however if any of these estima approximations to th ted by the best writ any in existence at th tes that a glass of wate e height of its annual Sar of mud. "No won Bing waters should qu its delta should enc ter who resided man computed with g ich that river discha stimate amounted, duri sand cubic feet, for er is at its greatest h and consequently its y discharged per sec undred and five thou Mr. Lyell has mad lid matter carried e examples of the effects of running water in g the surface of the Globe are sufficient for the s intended. In all parts of the world, such effects stantly taking place, to a greater or less extent. aggregate accumulation of solid ground by the forand extension of deltas on the surface of the whole must be very considerable during every year; and e effects are hardly appreciable in relation to the they produce on the entire surface of the globe. e, that the course of navigation is in a few instanructed, or changed, by these accumulations, but in the same sea ports of which the earliest records ry give any account, are still accessible. ccumulations commenced at very remote ne have contended, and continued to the is quite certain that many lakes now existe become dry land, and that the deltas of nto the sea, would have been far more exe find they are. nnected with the ry land, tend to All the facts, therefore, effects of rivers in the show that the present th has not existed more than a few thou1 that it has suffered no considerable chaning streams, as one of the causes now in TY OF SEDIMENT IN RIVER WATER. the preceding pages given such an account f rivers in forming solid depositions, as our ow, it is proper here to present the geologith an account of the estimates and experihave been made, to ascertain the quantity of ater is capable of holding in suspension. r, however, that we should also state, that these estimates, can be considered as more nations to the truth; still they are such as are best writers, and are probably as accurate tence at the present day. Major Rennell ass of water taken out of the Ganges during its annual flood, yields about one part in 66 No wonder, then," says he, "that the subshould quickly form a stratum of earth, or should encroach upon the sea." The same sided many years in the vicinity of the Gand with great care the quantity of water wwer discharges into the sea, and which by his inted, during a year, on an average, to eighty c feet, for every second of time.. When the greatest height during its annual inundation, ntly its motion much accelerated, the quaned per second, by the same estimate, was four five thousand cubic feet. has made a computation of the quantity of 66 experiment of Major Rennell, and his estimate of ntity of water it discharges. If it were true," "that the Ganges in the flood season contained in four of mud, we should then be obliged to supt there passes down every four days a quantity of al in volume to the water which is discharged in se of a day, or twenty-four hours. If the mud be to be equal to one half the specific gravity of (it however is more,) the weight of matter daily lown in the flood season would be about sixty e weight of the great pyramid of Egypt. If the discharges 405,000 cubic feet of water per second, as the estimate of Major Rennell, then, in round the quantity of mud discharged per second, e 100,000 cubic feet, which being multiplied by he number of seconds in 24 hours, would give 0,000 cubic feet of mud going down the Ganges The weight of this (allowing as above) would to that of 4,320,000,000 cubic feet of granite. out twelve and a half cubic feet of granite weigh t throwing out the half, the matter discharged by ges every day is 360,000,000 of tons. es the weight of the great pyramid of Egypt, which s computed to weigh 6,000,000 of tons." This is DESTRUCTION a consider ble nur this difficult subject. before satisfactory ker, certain, that great red by running strea a pods there can be no g up and that if the sa are described, all these bu ced by dry land. Butchere can be no possi ared for such an even ter which streams tran ing in proportion, as el of the country in whic ire, a lake may rem reciable elevation of its The great depth of some though the Ganges may be supposed to transport greater quantity of mud, even according to its n any other river, still there can be little doubt or Rennell very far over-rated the quantity of atter its waters contained. The Rhine, when oded, has been computed to contain one part of hundred of water, and Sir George Staunton by observations, calculated that the water of Yellow - China, contained earthy matter in the proportion art to two hundred. In this proportion he estiat the waters of that river brought down 48,000,000 feet of solid matter daily. ding to the calculations of Manfredi, the celebrain hydrographer, the average amount of sediment e running streams on the globe, is one part in 175. ch data, he estimates that it would take a thours to raise the general bed of the sea a single foot, none of this sediment was thrown back again = shores. what has been stated, the reader will observe that se circumstances are co ness of the present or quely, of the truth With respect to the lev at no change has taken State at this place, th de remains of Roman b an sea has not change We may therefore con Batter carried into the s e with its general lev Brown on the land at o er. siderable number of experiments have been ifficult subject, there remains much more to e satisfactory results can be offered. It is in, that great quantities of solid matter are running streams; and with respect to lakes re can be no doubt, but they are gradually that if the same causes continue which we 1, all these bodies of water will finally be y land. an be no possible estimate made of the time such an event, since the quantity of solid streams transport, must be constantly deroportion, as lakes and ponds approach the untry in which they are. In a flat country ake may remain for centuries without any levation of its bottom. depth of some lakes at the present day, when stances are considered, is a good proof of the he present order of things on the earth, and of the truth of the Mosaic history of its crea ect to the level of the sea, it has been shown ge has taken place in the Baltic, and we may this place, that it will be seen hereafter, that of Roman buildings show that the Mediterras not changed its level for the last 2000 years. erefore conclude, that either the quantity of ed into the sea has made no appreciable differs general level, or that as much solid matter is he land at one place as is carried into it in an DESTRUCTION OF ROCKS. es now described which have produced changes ace of the earth, are chiefly such as transport ials from one place to another. But there is use of change, which although noticed in the this article, must be more particularly describis the destruction of rocks. ontemplating," says Dr. Macculloch," the tow r is at first impressed with the character of d solidity, which nature here seems to have her works, it requires but a moment's reflecv that every thing around him bears the marks decay. Here he learns to withhold his regret hable nature of all human labors,-at the fall g tower, and the solid pyramid, when he sees st massive rocks, those mountains which seem or eternal duration, bear alike the marks of ind the traces of ruin." se great revolutions, however, other agents rate; and the first here to be considered is the st. Expanding as it freezes, the water which the fissures acts with irresistible force, and se enormous masses, which in the seasons of spring, daily fall from the mountains. In it is said that these effects often take place e emulating thunder; but if less conspicuous, ficiently common in all alpine regions that are he extreme vicissitudes of heat and cold."›l. i. p. 248. ause, in a great measure, is to be attributed the cliffs, which on some coasts present such striingular appearances. The constant action of ashing the inferior parts of these cliffs, also effects, and is often the cause of large masses itated into the water. The perpetual rubbing ler stones against the larger, on the borders of nother cause which in the course of time prolerable effects; and hence all such stones have angles, and become completely smooth and Iount Grenier. The fall of a part of Mount e of the calcareous mountains of Savoy, illusfects of frost, and the gradual undermining of rrents. Mount Grenier is upwards of 4000 and rises abruptly above the plain on which it e top, or cap, is an immense mass of limeeet thick, below which are strata of a softer is to the decay of the latter that the fall is at cap being undermined by the gradual erosion 1 of the under strata. The fall took place in 248. The larger masses, says Mr. Bakewell, y came from the upp ch distances, as to cover eral days, mass after ma Large hill. |