1(> ON CHANGES IN THE DISPOSITION 



of a lake may be at once lowered, though the general 

 cause is far more tedious. It is by its occasional in- 

 undation that the Nile raises the valley of Egypt, 

 while its daily actions are merely extending the Delta. 

 Such too is the action of the similarly situated river 

 of Ava, and others of Eastern Asia, and thus do the 

 Wolga, the Yellow river, and others, raise the sur- 

 rounding plains by their enormous and durable inun- 

 dations. It must however be recollected, that all 

 alluvia are not the produce of rivers, as has rashly 

 been asserted; and that we may often form erroneous 

 judgments respecting the effects of these, by attribut- 

 ing to them what has been produced by other causes. 

 But this question must be reserved to a future period; 

 at present, it is sufficient that I have stated the possible 

 exceptions. Nor let any one imagine that if all these 

 results demand Time, any thing is here implied, 

 respecting a parallel antiquity in terrestrial beings. 

 The present view refers only to the state of a vacant 

 earth, preparing for the habitation of animals, and is 

 a period respecting which we may freely enquire. 



The quantity of the alluvia, in various places, leads 

 us to conjecture of the times during which these ac- 

 tions must have existed, and thus, of the far distant 

 period when first the rivers descended from the naked 

 mountains and the sea rolled every where against a 

 rocky shore. At Amsterdam, 230 feet in depth of alluvial 

 soil have been penetrated, consisting of alternations of 

 sand, clay, gravel, earth, peat, and sea shells. In our 

 own island, the flat aestuaries of the Thames, the Tay, 

 the Forth, and many more, have been filled to their 

 present state by the produce of the hills. But these 

 are trifling examples; a single case of some magnitude 

 is preferable to thousands such which might be quoted, 

 , could I give a volume where I am limited to a brief 

 chapter. From the Puranas, we learn that long before 



