290 rHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



climate in the lake country ; an increase"* of evaporation from it, 

 because a decrease of precipitation upon it ; and, consequently, a 

 diminution of cloudy screens to protect the waters of the lakes 

 from being sucked up by the ra3'S of the sun ; and consequently, 

 too, there would follow a low stage for water-courses, and a 

 lowerino: of the lake-level would ensue. 



539. Examples. — So far, I have instanced these cases only 

 hypothetically ; but, both in regard to the hydrographical basins 

 of the Mexican Gulf and American lakes, I have confined mj^self 

 strictly to analogies. Mountain ranges have been upheaved 

 across the course of the winds, and continents have been raised 

 from the bottom of the sea ; and, no doubt, the influence of such 

 upheavals has been felt in remote regions by means of the winds, 

 and the effects which a greater or less amount^of moisture brought 

 by them would produce. In the case of the Salt Lake of Utah, we 

 have an example of drainage that has been cut off, and an illus- 

 tration of the process by which Nature equalizes the evaporation 

 and precipitation. To do this, in this instance, she is salting up 

 the basin which received the drainage of this inland water-shed. 

 Here we have the appearance, I am told, of an old channel by 

 which the water used to flow from this basin to the sea. Sup- 

 posing there was such a time and such a water-course, the water 

 returned through it to the ocean was the amount by which the 

 precipitation used to exceed the evaporation over the whole 

 extent of country drained through this now dry bed of a river. 

 The winds have had something to do with this ; they are the 

 agents which used to bring more moisture from the sea to this 

 water-shed than they carried away ; and they are the agents 

 which now carry off from that valley more moisture than is 

 brought to it, and which, therefore, are making a salt-bed of 

 places that used to be covered by water. In like manner, there 

 is evidence that the great American lakes formerly had a drainage 

 with the Gulf of Mexico ; for boats or canoes have been actually 

 known, in former years, and in times of freshets, to pass from the 

 Mississippi River over into the lakes. At low water, the bed of 

 a dry river can be traced between them. Now the Salt Lake of 

 Utah is to the southward and westward of our northern lake 

 basin ; that is the quarter (§ 357) whence the rain- winds have 

 been supposed to come. May not the same cause which lessened 

 the precipitation or increased the evaporation in the Salt Lake 

 water-shed, have done the same for the water-shed of the great 



