144 NATUKAL HISTORY OF 



CURRENTS OF THE MEDITERRANEAN. 



But the isthmus, connecting Egypt with Asia, did not exist 

 at the commencement of the present geological arrangement. 

 The Arabian prolongation of volcanic galleries may, indeed, 

 have dug the channel of the Red Sea, since, on the Abyssinian 

 sides, mephitic lakes and a sulphurous soil reach from the 

 coast to the mountains, and chains of dormant craters pass 

 behind the coast, in a south-east direction, even beyond the 

 equator. So, likewise, on the west of the Nile, extensive 

 tracts, bordering on the desert, manifest igneous activity, not 

 far below the surface, in ebullitions assuming various fantastic 

 forms. From the period, however, when the Straits of Calpe, 

 the Bisepharat of Phoenician navigators, admitted the Western 

 Ocean, to give the present form and extent to the Mediter- 

 ranean, anteriorly supplied with very little fresh water, it may 

 be supposed that the evaporation, being more counterbalanced 

 by the influx, passing mostly eastward in the straits, and still 

 more at a great depth below the surface, raised the sea to a 

 higher level, and caused the circular course, which now, flowing 

 eastward along the coast of Barbary, casts all river deposits, 

 brought down that shore, into the recess of the two Syrtes, and 

 near the summit of the Mediterranean, sweeps onward all the 

 Nilotic discharges. At the commencement of the present 

 superficial terrene system, when the current first acted upon 

 the efflux of the river, it threw, similarly as in the Syrtes, all 

 deposits back upon the coast, and filled the channel of com- 

 munication from the Red Sea, whose level, somewhat higher, 

 was kept in check by the prevailing northerly winds, until a 

 bank was formed and marshes created, which the same northerly 

 winds, acting upon the sea-shore, would supply with dust, and 

 all other currents of air aided to fill up, until the isthmus was 

 formed, and the delta had advanced to the edge of deep water, 

 when first it came within the force of the real sea current. 

 Thus, a space of 72 miles, from Suez to El-Arish, and nearly 



