CHANGES IN OCEANIC REGIONS. 37 1 



carried down in the flood season would be about equal to seventy-four times the weight 

 of the Great Pyramid of Egypt. He observes: "405,000 cubic feet of water per 

 second gives in round numbers 100,000 cubic feet of mud per second, which x 86, 400, 

 the numbers of seconds in twenty-four hours, =8,641,100,000, the quantity of cubic 

 feet of mud going down the Ganges per diem. Assuming the specific gravity of mud to 

 be half that of granite, the matter would equal 4,320,550,000 feet of granite. Now 

 about twelve and a half cubic feet of granite weigh one ton ; and it is computed that the 

 Great Pyramid of Egypt, if it were a solid mass of granite, would weigh about 6,000,000 

 of tons." There is some reason to doubt the accuracy of Rennell respecting the quan- 

 tity of earthy matter in the water of the Ganges, though it is generally agreed to be the 

 most turbid river upon the face of the globe, owing to the lightness of the soil of the 

 Bengal plains favouring its transportation by the current, and the great violence of the 

 tropical rains. Supposing it therefore to hold but -j J- th part of mud in suspension, in- 

 stead of ^, an estimate given with reference to the Rhine when most flooded, the result 

 will still be, that the river discharges in two days a mass of matter equal in bulk and 

 weight to the Great Pyramid. A considerable portion of this goes to form new land 

 along the coast at the mouth of the Ganges, but a large quantity is swept onwards into 

 the Bay, of Bengal, and contributes to lay upon its floor a carpet of soil in course of per- 

 petual renewal. 



The Sea of Azov, well-known to the Greeks and Romans under the name of Mseotis, 

 was believed in the time of Aristotle to be filling up by the earthy matter conducted into 

 it by its rivers. Its excessive shallowness now has no doubt been produced by the 

 alluvium principally discharged by the Don, the average depth of the main body of the sea 

 being only between six and seven fathoms. The Yellow Sea, an arm of the Chinese 

 Ocean, so called from its waters being coloured by an intermixture of particles of yellow 

 mud, supplies a similar example of the accumulation of debris in its bed. It receives the 

 rapid Hoang Ho, one of the largest rivers of China, which carries along with it an 

 immense quantity of earthy material in a state of solution in its waters. Sir George 

 Staunton calculated that this powerful stream brought down in a single hour two million 

 feet of earth, or forty millions daily ; so if the Yellow Sea be taken to be 120 feet deep, 

 the river will convert an English square mile into firm land in seventy days. Currents 

 carry far away into the ocean much of the sediment it receives, but the immediate depo- 

 sition of the major part produces gradually increasing shoals and shallows, which interfere 

 with the navigation. Captain Hall in the Lyra, sailed across this sea in 1816 on his 

 voyage to Loo Choo, and had occasion to apprehend fairly sticking in the mud several 

 times in the passage. When no land could be perceived from the mast-head, the ship 

 was in less than five fathoms of water, and upon the ebb of the tide, its bottom was within 

 three feet of the ground. It was discovered, at one time, that the Lyra was actually 

 sailing along with her keel in the mud, indicated sufficiently by a long yellow train in her 

 wake. There was more apparent than real danger in this extreme shallowness, as it was 

 found, by forcing long poles into the ground, that for many fathoms below the surface on 

 which the sounding lead rested, and from which level the depth of water is estimated, the 

 bottom consisted of nothing but mud formed of an impalpable powder, without the least 

 particle of sand or gravel. The fact unquestionably is, that the bottom of the Yellow 

 Sea is gradually rising, from the deposits of innumerable streams flowing into it from 

 China and Tartary, and in process of time, this arm of the ocean, which has probably an 

 extent of 125,000 square miles, will become terra firma, exhibiting a horizontal plain like 

 the great deltas of the Nile and the Ganges. 



While, by the action of rivers, soil is transported from far inland situations, and brought 

 into the sea, it is borne by the currents of the ocean, which sweep along the coasts, to a 



