File:Calcutta journal of natural history, and miscellany of the arts and sciences in India (1841) (14582213918).jpg

Identifier: calcuttajournalo02mccl (find matches)
Title: Calcutta journal of natural history, and miscellany of the arts and sciences in India
Year: 1840 (1840s)
Authors: McClelland, John, d. 1883
Subjects: Natural history
Publisher: Calcutta, Bishop's College Press
Contributing Library: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library
Digitizing Sponsor: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library

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of that deluge, which in its retirement from the land, dispersedthem abroad, by its cuirents, from the places where they had been ori-ginally deposited. These then, in contradistinction to the stratifiedbeds of the true diluvium, may be properly termed, diluvial detritus. With regard to the lapse of time required to form a given portion ofthe Gangetic Delta, we are, I conceive, altogether left without any cer-tain data; for so much must always depend upon the depth to be filledup, and the quantity of detritus brought down, that the periods wouldvary greatly in duration. Thus the failure or mildness of the Monsoon for several, or even fora few, seasons, would materially retard the formation of new land, bylimiting the supplies of transported matter ; while afterwards, in a pe-riod of equal duration, but in which the rains had been heavy, anddetritus abundant, a larger share of deposits would be recovered fromthe sea. If now during both these terms, observations should be made t i *§ 1
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Calcutta Delta. 547 by different individuals, the first would be inclined to assign long lapsesof time for the formation of the Delta; while the other would, from hiscollected data, argue precisely the reverse. Could we know the mean or extreme rate of production of stratifieddeposits at the present day, this would enable us to conjecture thelengths of some geological periods, and with double hazard refer othersto this conjectural scale; but even this unsatisfactory estimate wouldbe liable to the further and fatal error of not knowing the ratio ofthe forces in the different periods. To assume this ratio, is only to aug-ment in a still higher degree the amount of improbability.* It is only, therefore, from facts stored up through a considerable num-ber of years, that we can ever hope to obtain anything like an approxi-mation to the truth ; yet this very country in which the opportunitiesfor studying nature in her grandest scale are most abundant, is un-fortunately likewise that, in whi

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