IXTKODK TION TO UKroilT AND JOURNAL. 89 



Meadows, according to Beckwith, 4,147 feet 



3,840 feet. 



5th. Walker's River Basin, elevation of lowest point above the sea, 7 miles above 

 Walker's Lake, 4,072 feet. 



(Walker's Lake Basin estimated at about same as Carson, 3,840 feet.) 



Gth. Owen's Lake Basin, altitude unknown. 



7th. Mojave River Basin, estimation of lowest point above the sea (Williamson), 

 1,111 feet. 



All these valleys or sub-basins, it will be noticed, are along the outskirts of the 

 Great Basin, just within its circumference; and as the valleys of the great central area 

 have an average altitude of about 5,600 feet, which is, for much the larger portion of 

 the area, about 1,500 feet higher than said basins, and for the Mojave portion over 4,oi)0 

 feet higher, it will at once be apparent that, as a whole, the Basin should be conceived 

 as an elevated central region extended over much the greater portion of the Basin, ami 

 in proximity to the circumference, sloping toward the sub-basins bordering the cir- 

 cumference. When this idea is entertained, and this extended central portion is in 

 addition conceived of as being traversed by high and extensive ranges of mountains, 

 on an average about 15 miles apart, ranging north and south, and correspondingly cor- 

 rugated with intermediate valleys of commensurate lengths, and the mind conceives at 

 the same time that the order of depression of the basins is from Lake Sevier, where it 

 is least, around successively by Great Salt Lake, Humboldt River Valley, Carson 

 Lake, Walker's Lake, to the valley of the Mojave, where it is much the greatest, a 

 very good mental daguerreotype can be had of the Great Basin inside of its inclosing 

 mountains. From this description I think it will be obvious that, while the so-called 

 Great Basin is in some small degree a basin of lakes and streams, it is pre-eminently 

 a basin of mountains and valleys. 



In regard to the geological character of the mountains within the Great Basin, I 

 would remark that, from Camp Floyd west, as far as about Kobah Valley, those of 

 carboniferous origin much predominate ; though over the desert proper, between 

 Simpson's Springs and the Tots-arr range, the igneous are the characteristic ; and near 

 the Humboldt range those of Devonian age obtain. From Kobah Valley to the Sierra 

 Nevada the ranges are almost exclusively of igneous origin, and present few indications 

 of stratified rocks. The knowledge, geologically, of this extensive terra incognita, now 

 for the first time given to the public in the reports of my assistant, Mr. Engelmann, 

 and Mr. Meek, the paleontologist, is an interesting result of the expedition, and will go 

 far to fill up the gap that remained to complete the geological profile of our country 

 from the Atlantic to the Pacific, on the line of our explorations. These reports, it will 

 be noticed, do not only discuss the geology and paleontology of the Great Basin, but 

 of the whole route through from Fort Leavenworth to the Sierra Nevada, and to no 

 two geologists, probably, could the work have been better assigned, since Mr. Engel- 

 mann was the geologist" of Lieutenant Bryan's expedition to the Rocky Mountains in 

 1856, and of my expedition all the way from Fort Leavenworth to Sierra Nevada and 



