Calcutta Delta. 549 



Rhine and the Meuse ; and thus the richest districts of Holland 

 have continually the frightful view of their rivers held up by embank- 

 ments, at a height of from 20 to 30 feet above the level of the land."* 

 This rising is undoubtedly accelerated in these instances by the 

 practice of embanking the rivers, but " M. Weibeking, the director of 

 bridges and highway in the kingdom of Bavaria, shews that the proper- 

 ty of raising the level of their beds is common in a greater or less 

 degree to all rivers."f 



It is evident then that a consideration of the causes now in operation 

 will not always furnish us with the surest means of calculating the 

 time occupied in forming the dry land of bygone years, since it becomes 

 apparent on reflection, that not only have great fluctuations in, the 

 quantity of detritus, and force of rivers taken place, but also that 

 the farther the Delta is carried onwards into the sea, the longer will be 

 the time required to cause a new portion to rise above the waters, and 

 this simply from the fact, that the farther we recede from the moun- 

 tainous tracts of any country, the deeper becomes the Ocean, and con- 

 sequently the longer time will the alluvium be in accumulating suffi- 

 ciently to appear above the surface. 



Thus, if we calculate the age of our Indian alluvial continents, by 

 the time we find to elapse in forming a square mile above the sea, in 

 the present day, we shall probably err considerably, for it will be 

 evident at once, from the annexed figure, that the alluvial land at A. 

 would take a longer time to appear above the water B. than when 

 it was forming in the neighbourhood of C. 



Delta. 





Supposing therefore that the supplies of detritus from the hills was 

 at all times equal, the land would have formed more rapidly in former 

 days than at present, because the depth to be filled up was not so great 

 as now, and if this be true, and land did actually accumulate more 

 quickly in former times, it is evident that no such lapse of years would 

 be required as modern theorists assume to be the case. 



* Jameson's, Cuvier's Theory of the Earth, 

 t Ibid. 



