the hand at the Head of the Persian Gulf, 45 



Next will have to be investigated the particular operation 

 of the causes which have produced the changes in the coast 

 line ; the principal of which causes are the transporting action 

 of the rivers on the one hand, and the counteracting influence 

 of the tides and current on the other. By the simple operation 

 of the former of those causes, a progressive deposition of al- 

 luvial matter would have taken place, which would have been 

 even and regular throughout: by the operation of the latter 

 cause, however, that deposition would not merely have been 

 obstructed, but its regularity and equal character materially af- 

 fected ; and in the same way as it has been shown * that the 

 current from the westward in the Mediterranean has occa- 

 sioned a general declination of the waters of the Nile from 

 east to west, and has obstructed, and indeed in some cases 

 closed up, the more eastern branches of that river, so by the 

 operation of the current at the head of the Persian Gulf, would 

 the western branches of the Euphrates gradually have become 

 impeded, and finally closed : and further, as in the progress 

 of time the deltas of the Euphrates and Tigris became con- 

 tinuous, the current of the former river would gradually have 

 become so obstructed, that, in the end, it would (like the 

 Rhinef) have lost its separate course to the sea, and would 

 be destined to form a tributary to its more favourably situated 

 rival. 



It will likewise be necessary to ascertain what islands ori- 

 ginally existed in the Persian Gulf below the mouths of the 

 rivers ; as their presence will very materially have influenced 

 the direction and the rate of the formation of new lands in 

 their vicinity J. 



In considering the progress of the changes in the configu-^ 

 ration of the new lands which will thus have been formed, but 

 which, in many cases, will also have been subjected to de- 

 struction from the effect of the currents of the rivers and the 

 shifting of their channels, as well as from the effect of the 

 tides and currents of the sea, it may perhaps, under any cir- 

 cumstances, be impossible to determine anything decisive as 

 to their geographical outline and character at any former de- 

 terminate period ; but we may yet be enabled to obtain the 

 idea (however faint) of the mouths of the Euphrates having 

 first been impeded by shoals and sand-banks formed along 

 the base of the separate delta of that river ; — next, of the for- 

 mation of one or more lakes through which the branches of 



* 0,>ig. Bi6l., pp.172, 173. 



t Principles of Geology, vol. i. p. 286. 



X These islands will now, of course, form part of the main land. 



