302 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



are entitled to regard it as probably correct, until a train of 

 coincidences at least as striking can be adduced to show that such 

 is not the case. Kcturning once more to a consideration of the 

 geological agency of the winds in accounting for the depression 

 of the Dead Sea, we now see the fact palpably brought out before 

 us, that if the Straits of Gibraltar were to be barred up, so that 

 no water could jisiss through them, we should have a great 

 depression of water-level in the Mediterranean. Three times as 

 much water (§ 547) is evaporated from that sea as is returned to 

 it through the rivers. A portion of water evaporated from it is 

 probabl}' rained down and returned to it through the rivers ; but, 

 supposing it to be barred up : as the demand upon it for vapour 

 would exceed the supply by rains and rivers, it would commence 

 to dry up ; as it sinks down, the area exposed for evaporation 

 would decrease, and the supplies to the rivers would diminish, 

 until finally there would be established between the evaporation 

 and precipitation an equilibrium, as in the Dead and Caspian 

 Seas. But, for aught we know, the water-level of the Mediter- 

 ranean might, before this equilibrium were attained, have to 

 reach a stage far below that of the Dead Sea level. The Lake 

 Tadjura is now in the act of attaining such an equilibrium. 

 There are connected with it the remains of a channel by which 

 the water ran into the sea ; but the surface of the lake is now 

 five himdred feet below the sea-level, and it is salting up. If 

 not in the Dead Sea, do we not, in the valley of this lake, find 

 outcropping some reason for the question, What have the winds 

 had to do with the phenomena before us ? 



554. Hoio, hy the winds, the age of certain geological 'plienomena in 

 our Jiemispliere may he compared with the age of those in the other. — 

 The winds, in this sense, are geological agents of great power. 

 It is not impossible but that they may afford us the means of 

 comparing, directly, geological events which have taken 2)lace in 

 one hemisphere, with geological events in another : e.g., the tops 

 of the Andes were once at the bottom of the sea. — AN'hich is the 

 oldest formation, that of the Dead Sea or the Andes ? If the 

 former be the older, then the climate of the Dead Sea must 

 have been hygrometrically very different from what it now is. 

 In regarding the winds as geological agents, we can no longer 

 consider them as the type of instability. We should rather treat 

 them in the light of ancient and faithful chroniclers, which, upon 

 being rightly consulted, will reveal to us truths that Nature has 



