GEOLOGY. 311 



subsidence, which has been going on contemporaneously with the accumu- 

 lation of lluviatile mud. Captain Strachey, of the Bengal Engineers, has 

 estimated that the Ganges must discharge 4 times as much water into the 

 Bay of Bengal as the same river carries past Ghazipore, a place 500 miles 

 above its mouth, where experiments were made on the volume of water 

 and proportion of mud by the Hev. Mr Everest. It is not till after it has 

 passed Ghazipore that the great river is joined by most of its larger tribu- 

 taries. Taking the quantity of sediment at one-third less than that as- 

 signed by Mr. Everest for the Ghazipore average, the volume of solid 

 matter conveyed to the Bay of Bengal \\ould still amount to 20,000,000,000 

 of cubic feet annually. The Ganges, therefore, might accomplish in 

 375,000 years the task which it would take the Mississippi, according 

 to the data before laid down, upwards of two million years to achieve. 

 One inducement to call attention to such calculations is the hope of in- 

 teresting engineers in making accurate measurement of the quantity of 

 water and mud discharged by such rivers as the Ganges, Brahmapootra, 

 Indus, and Mississippi, and to lead geologists to ascertain the number of 

 cubic feet of solid matter which ancient fiuviatile formations, such as the 

 coal measures, with their associated marine strata, may contain. Sir 

 Charles anticipates that the chronological results derived from such sources 

 will be in harmony with the conclusions to which botanical and zoological 

 considerations alone might lead us, and that the lapse of years will be 

 found to be so vast as to have an important bearing on our reasonings in 

 every department of geological science. A question may be raised, how 

 far the cooperation of the sea in the deposition of the carboniferous series 

 might accelerate the process above considered. The lecturer conceives _ 

 that the intervention of the sea would not afford such favorable condi- 

 tions for the speedy accumulation of a large body of sediment within a 

 limited area as would be obtained by the hypothesis before stated name- 

 ly, that of a great river entering a bay in which the waves, currents, and 

 tides of the ocean should exert only a moderate degree of denuding and 

 dispersing power. An eminent writer, when criticizing, in 1830, Sir 

 Charles Ly ell's work on the adequacy of existing causes, was at pains to 

 assure his readers, that while he questioned the soundness of the doctrine, 

 he by no means grudged any one the appropriation of as much as he 

 pleased of that " least valuable of all things, past time." But Sir Charles 

 believes, notwithstanding the admission so often made in the abstract of 

 the indefinite extent of past time, that there is, practically speaking, a 

 rooted and perhaps unconscious reluctance on the part of most geolo- 

 gists to follow out to their legitimate consequences the proofs, daily in- 

 creasing in number, of this immensity of time. It would therefore be of 

 no small moment could we obtain even an approach to some positive 

 measure of the number of centuries which any great operation of Nature, 

 such as the accumulation of a delta or nuviatile deposit of great magnitude, 

 may require, inasmuch as our conceptions of the energy of aqueous or 

 igneous causes, or of the powers of vitality in any given geological period, 



