APPENDIX TO KEPOKT OF THE SECRETARY. 75 



Howard Stausbury and Mr. Clarence King show that from 1850 to 18G9 

 the total area of the water surface increased from 1,750 to 2,1CG square 

 miles, or nearly 24 per cent. By this expansion the surface for evapo- 

 ration was increased, so that the lake could return to the atmosphere the 

 surplus thrown into it by the augmented streams. 



Whatever laud is at any time flooded by the lake becomes saturated 

 with salt, and, if the water afterward retires, remains barren of vegeta- 

 tion for many years. The highest level readied by the water in storms 

 is marked by a line of driftwood and other debris. Above this line there 

 is usually a growth of grass and sage-brush, but below it nothing grows. 

 Previous to the last great rise of the lake the storm-line was six feet 

 lower than at present, and the intervening belt of land still retains the 

 stumps and roots of bushes that have been killed by the advancing brine. 

 The encroaching water overran the ancient storm-line in about the year 

 186G, and for the past eleven years it has covered ground which had 

 been exempt from incursions of brine for a time sufficient to permit the 

 rains to cleanse the soil, and for a further time sufficient to produce a 

 growth of sage-brush. The whole period is as likely to have been meas- 

 ured by centuries as by decades. 



Thus it appears that the last twelve years have witnessed an exten- 

 sion of the lake which is not only without precedent in the experience 

 of the citizens of Utah, but is clearly an anomaly in the history of the 

 lake. To explain it, and to explain at the same time the increase of the 

 streams, there are two general theories worthy of consideration. 



The first is that there has been a change of climate in Utah whereby 

 the atmosphere is moister, so that the fall of rain and snow has become 

 greater and the rate of evaporation has become slower. The second is 

 that the industries of the white man, which have been steadily growing 

 in importance for the last thirty years, have so modified the surface of 

 the laud that a larger share of the suow and rain finds its way into the 

 water-courses, and a smaller share is returned to the air by evaporation 

 from the ground. The latter theory, which is the one proposed by 

 Professor Powell, is considered by Mr. Gilbert the more probable, and 

 he finds reason to believe that the tax imposed upon the streams by the 

 work of irrigation is more than repaid by the effects of the draining of 

 marshes and the destruction of herbage and timber. A great volume of 

 water is turned upon the cultivated fields, and from their moist surfaces 

 is absorbed by the atmosphere without ever reaching the lake ; but, on 

 the other hand, the farmer has found it to his advantage to drain the 

 beaver-ponds and other marshes, and thus check the evaporation from 

 their surfaces, and the streams which he thereby rescues from dissipation 

 are used in irrigation for a few months only, while for the remainder of 

 the year they pay their tribute to the lake. The destruction of grasses 

 by herds of domestic animals and the cutting of trees upon the mount- 

 ains expose the ground to the sun and facilitate the melting of the snow ; 

 the removal of the grass opens the way also to a fieci circulation of sur- 



