276 PROCEEDINGS OF THE CALIFORNIA 



Dr. Blake read the following communication : 



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Remarks on the Topography of the Great Basin. 



BY JAMES BLAKE. M. D. 



In some remarks I made in May last, on certain points connected with the 

 position and height of the rim of the Great Basin in Humboldt County, Nevada, 

 I stated that the divide between the waters of the Great Basin and the Columbia 

 was situated much farther to the south than the position usually assigned to it 

 on our maps, and that its elevation was much less than is generally stated. 



Having recently visited this section of country, I can now furnish more accu- 

 rate data as to the position and height of divide, across which the waters of the 

 Great Basin escaped into the valley of the Columbia, at least that portion of 

 the divide situated near the 118th meridian. As regards its geographical 

 position, it has been arrived at by computation from the observed latitude and 

 longitude of Fort McDermott. The course from Wiunemucca was determined 

 by compass and measured by the roadometcr ; and the latitude and longitude of 

 tlie point thus ascertained was arrived at by computation from the latitude and 

 longitude of Fort McDermott, the nearest point at which any accurate astronom- 

 ical observations have been made for determining these data. The position 

 thus found is 41° 33' N. latitude, 118° 29' E. longitude.* The height of the 

 divide is 590 feet above the valley of the Queen's river, at the place where it 

 makes a bend to the southwest, to lose itself in the Black Rock Desert, and 390 

 feet above the level of the Humboldt valley at Winnemucca. and 450 feet above 

 the head of Puebla valley. It is formed by one of the terminal spurs of the 

 Vicksburg range. The gap in the range extends at about the same level for 

 four miles in a southeasterly direction, the easterly end being rather lower than 

 the westerly. From the north side of the divide two valleys run, one directly 

 opening into the north end of Puebla valley and the other joining the Wyllie 

 Creek valley, but opening into the main Puebla valley a few miles farther north. 

 From the north end of Puebla valley the waters all run north. Opposite the 

 station at Trout Creek, about eighteen miles from the head of the valley, there 

 has been a fall of about fifty feet, and the waters of the creek run north from 

 the station for a distance of si.x miles before spreading out to form a lake, the 

 first two miles with a fall of thirty feet to the mile, so that the valley, at the 

 sink of Trout Creek, must be one hundred feet lower than at the head. To the 

 north of the sink of Trout Creek a low divide, not more than a few feet in height, 

 and probably formed by drift sand, separates the waters of Trout Creek from the 

 streams coming from the east side of Stein's mountain. These streams form an 

 extensive series of lakes, extendius: for some miles along the foot of the mountain; 



* In these measurements I have calculated the height from a comparison with the height of 

 the barometer at the summit of the Sierra Nevada. 



Some four days having been spent at Winnemucca taking observations, the altitude thus 

 obtained was found to difl'er by about 100 feet from the altitude as measured by the railroad 

 surveys. I shall have some remarks to make on this anomaly at a future meeting. 



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