kind is the cause of an obstruction to the winds, and 

 forms a nucleus, around which the dust and sand, which 

 are wafted over these districts, are deposited, elevating 

 and extending the ground, and thus, annually encroach- 

 ing on the amcient limits of the sea. 



That this has been, in part, the nature and progress 

 of the formation of those deltas, there can be no doubt; 

 for they have been, from the earliest periods of time, 

 and are still, inhabited ; for Mr. Rennell observes, 

 when describing certain tides, or irruptions of the sea 

 in those parts, which rush in with great violence, that 

 the people, inhabiting the parts of the delta most ex- 

 posed, are under the necessity of repairing, with their 

 families, immediately to boats kept for that purpose, 

 and in which they are compelled to stay, until the sub- 

 sidence of the waters. Those who are so unfortunate, 

 as not to secure their safety in boats, from the dreadful 

 violence of these irruptions, called by the natives Bore, 

 are inevitably swept away and perish.* 



But neither the alluvion brought down by those ri- 

 vers, nor the labours of man can be considered in any 

 other light, than as having contributed, in part, to the 

 formation and extension of those deltas. 



Another more powerful auxiliary presents itself, as 

 having afforded its constant aid, in the accomplishment 



* See Rennell's Map of Hindostan, page 229, on the sudden 

 rise ol the tide- at the Indus ; in the gulf of Cambray and Cutch, 

 and also at the Ganges. 





