378 



tion of this process, for a series of years, the grounds 

 adjacent to a river would be brought up to a perfect 

 level with the banks, by the time that they cease to be 

 overflowed. But is this the case ? I answer no ; not, 

 perhaps, in a solitary instance. On the contrary, the 

 banks continue to increase in height until they are ele- 

 vated so far above the highest inundation as seldom, 

 if ever to be overflowed, while the lands adjacent con- 

 tinue low, and are, perhaps, annually inundated. 



This state of things will be found to exist on many 

 of the rivers in America, on all the deltas of which I 

 have taken notice, and particularly that of Egypt ; of 

 which Dr. Shaw has said, '< For whereas the soil of 

 other plain countries is usually of the same depth, here 

 we find it vary in proportion to the distance from the 

 river, being sometimes near the bank more than thirty 

 feet high, whilst at the utmost extremity of the inunda- 

 tion, (viz ) at the skirts of the valley, and next to the 

 hills, it is not the quarter part of so many inches."* 



Whatever may have been the opinion of Dr. Shaw, 

 respecting the fact above quoted, it may be remarked, 

 that it is not peculiar to the banks of the Nile, nor the 

 valley of Egypt ; on the contrary, it is almost univer- 

 sal in all alluvial districts, on the borders of rivers, 

 and the cause of which may be accounted for, or ex- 

 plained in the following very easy and rational man- 

 ner, viz : by the operations of the winds, sometimes 



* Shaw's Travels, page 439, for remarks on this passage, see 

 pages 304 and 305. 



