4S0 Correspondence — " The Delta of the Nile.'' 



geographers or geologists, so far from anticipating the interesting- 

 discoveries of Mr. Meyer, would almost appear to have conspired to 

 perpetuate the vulgar errors current upon the subject. Thus, in 

 treating of existing deltas, they have actually represented their 

 waters as ramifying in innumerable sluggish streams, or collecting 

 into vast swamps, stagnant lagoons, and shallow lakes, often of 

 great size ; with remarkable unanimity they have dwelt on the 

 extreme fineness of the sediments in thesq waters, and the slowness 

 with which they were deposited ; but, strange to say, the existence 

 of the characteristic "shingle" they appear to have altogether over- 

 looked. Further, they have described some of the grandest deltas 

 in the world as formed in tideless seas. Unfortunately, too, the 

 disseminators of these erroneous views have been aided by the 

 naturalists, who have declared that the existing boring-molluscs are 

 all marine ; and they have been abetted by the palaeontologists, who 

 have described the ancient allies of these boring-molluscs as occur- 

 ring in such strata as the Loudon Clay and the "Lower Greensand," 

 and never in any freshwater beds at all, whether of estuarine or 

 lacustrine origin. 



"Where the error has been so universal, it may seem invidious to 

 particularize individual authors ; but I cannot refrain from pointing 

 out what appears to have been almost infatuation, with respect to 

 this subject, on the part of the author of "The Geological Observer." 

 Not content with describing in great detail the muddy character and 

 quiet mode of deposition of the delta sediments. Sir Henry De la Beche 

 has actually stated that 400 miles from its mouth the waters of the 

 Ganges can no longer move coarse gravel ! — and so far is he from 

 perceiving the necessary connexion between tides and deltas, that 

 he even represents the action of the former as altogether inimical to 

 the formation of the latter. So great, indeed, was his misapprehen- 

 sion on the subject, that he has actually founded the division into 

 chapters of part of his great work on the (of course, erroneous) sup- 

 position that deltas are only formed in " tideless seas," or in those 

 where, owing to the action of local causes, the tide is neutralized. 

 I need not point out how uniformly these errors have been adopted 

 by writers of less authority on physical geography and geology. 



Of course, by the interesting discoveries to which I have alluded, 

 large portions of our existing geological treatises are rendered obso- 

 lete, and will require to be re-written ; but great revolutions (even 

 of opinion) are seldom effected without causing some inconvenience 

 to individuals. Perhaps, therefore, I have little right to complain 

 of my own case, which is, nevertheless, one of some hardship. 



Formed of deposits which all observers, from Herodotus to Horner, 

 have agreed to call "mud" and not "shingle," — by streams which, 

 meandering over the level plains of Lower Egypt, and forming such 

 lakes as Bourlos, Menzaleh, and Mareotis, finally emj)ty themselves 

 into the tideless Mediterranean, — streams in whose waters, moreover, 

 no naturalist has ever yet succeeded in detecting a single boring- 

 mollusc, — I stand convicted by Mr. Meyer as a gross impostor, in 

 bearing the title by which I have so long been recognized, that of 



" The Delta of the Nile." 



