ON THE GEOLOGICAL AGENCY OF THE WINDS. ig] 



CHAPTER X. 



ON THE GEOLOGICAL AGENCY OF THE WINDS. 



To appreciate the Offices of the Winds and Waves, Nature must be regarded as a 

 Whole, <J 369. — Level of the Dead Sea, 370. — Evidences that at former Geolog- 

 ical Periods more Rain fell than now falls upon the Dead Sea and other inland 

 Basins, 371. — Where Vapor for the Rains in the Basin of the American Lakes 

 comes from, 375. — The Effect produced by the Upheaval of Mountains across the 

 course of vapor-bearing Winds, 376. — The Agencies by which the Drainage of 

 H3-drographic Basins may be cut off from the Sea, 380. — Utah an Example, 382. 

 — Effect of the Andes upon vapor-bearing Winds, 383. — Geological Age of the 

 Andes and Dead Sea compared, 391. — Ranges of dry Countries and little Rain, 

 393. — Rain and Evaporation in the Mediterranean, 399. — Evaporation and Precip- 

 itation in the Caspian Sea equal, 404. — The Quantity of Moisture the Atmosphere 

 keeps in Circulation, 407. — Where Vapor for the Rains that feed the Nile come 

 from, 409.— Lake Titicaca, 420. 



369. Properly to appreciate the various offices which the 

 winds and the waves perform, we must regard nature as a whole, 

 for all the departments thereof are intimately connected. If w^e 

 attempt to study in one of them, we often find ourselves tracing 

 clews which lead us off insensibly into others, and, before we are 

 aware, w^e discover ourselves exploring the chambers of some 

 other department. 



The study of drift takes the geologist out to sea, and reminds 

 him that a know^ledge of waves, winds, and currents, of navigation 

 and hydrography, are closely and intimately connected with his 

 favorite pursuit. 



The astronomer directs his telescope to the most remote star, 

 or to the nearest planet in the sky, and makes an observation upon 

 it. He can not reduce this observation, nor make any use of it, 

 until he has availed himself of certain principles of optics ; until 

 he has consulted the thermometer, gauged the atmosphere, and 

 considered the effect of heat in changing its powers of refraction. 

 In order to adjust the pendulum of his clock to the right length, 

 he has to measure the water of the sea and weigh the earth. He, 

 too, must therefore go into the study of the tides ; he must ex- 

 amine the earth's crust, and consider the matter of which it is 



