LAKES OF THE LAHONTAN BASIN. 



65 



jirevious to 1862. This lake, however, is thought by Mr. Frazier to be 

 much higher at present than wlien he first saw it. During tlie spring and 

 summer of 18b8 the Truckee delivered more water than usual, and Pyramid 

 Lake rose 10 or 15 feet. This rise continued throughout the following 

 year, and during these two years Pyramid overflowed into Winnemucca 

 Lake. The water in tlie "'slough" at that time was brackish and unfit to 

 drink. In the summer of 1876 all the water of the Truckee River emptied 

 into Winnemucca Lake, its outlet into Pyramid Lake having been closed 

 by a gravel bar; but the annual rise of the river the following spring re- 

 moved the obstruction. These observations, although not of scientific 

 accuracy, are yet of value, and have been confirmed by other people who 

 have been acquainted with these lakes for a number of years. 



We may note here that the rise of Pyramid and Winnemucca lakes 

 during the last fifteen or twenty years is synchronous with a similar in- 

 crease observed in Goose, Horse, and Mono lakes, California; Walker 

 and Ruby lakes, Nevada; Great Salt and Rush lakes, Utah. 



In determining future fluctuations of level in Pyramid and Winne- 

 mucca lakes, the accompanying map, Plate IX, may be considered as of 

 approximate accuracy; the soundings, too, were made with care. Besides 

 these data we have determined the elevation of certain points above the 

 surface of the lake, which will serve as bench-marks for future measure- 



ONE MILE 



Fig. 7. — Portiuu of the e.tst shore of Pyramid Lakf, showing position of measured rocks. 



ments. In the southern end of Pyramid Lake, and to the eastward of the 

 Truckee delta, rise a group of tufa crags, indicated on the map by the let- 

 ters X, y, z. An enlarged plat of this portion of the lake shore is given in 

 the accompanying figure. The height of these crags above the surface of 

 MoN. XI— 5 



