GEOLOGICAL KEPORT. 301 



Metallic ores were not observed, .and the geological formations are such that it 

 would be rather an exception to find any ores associated with them. 



Salts. — I have, above, mentioned beds of gypsum and rock-salt, in strata of 

 probably Triassic age; but, as part of them appear to reach beyond the limits of this 

 section, into section V, more will be said of them hereafter. 



Efflorescences of salts, on shales and slates, in the neighborhood of Green River, 

 have also been mentioned in the foregoing. 



SECTION V. 

 THE DISTRICT OF CENTRAL ANI 



LIMITS AND GENERAL CONFIGLRATION-TIIE IGNEOUS Ro< KS, THEIR CLASSIFICATION AND AGE- 

 METAMORPHIC AND ALTERED ROCKS— THE STRATIFIED RocKS-l ITER CARFioMFF.KoFS AND 

 PERMIAN, LOWER CARliONTFEROFS. DEVONIAN, ANT) OLD WED. si I.I THAN FORMATION'S -THE 



DRAINAGE OF THE 1 \ K ! - UnNM^llHI "I L\ AFoK M H i\ - -l'LIM.- \M' i K! I lo I.R \l K 

 ISH WATER-SUBTERRANEAN KESEEVOlES-HoT AND MINERAL MiMNGS-U ARM SI'EINos IN- 

 ROUND PRAIRIE, IN KOBAH VALLEY, ON WALKER RIVER, *C.— IMPBOVEMENTS !\ I III; sMTLY 

 OF WATER-ARTESIAN WELLS— TANKS— WELLS-SOIL AND YEOETATloX- \OKIi| III RE -MIN- 

 ERAL WEALTH— GOLD, SILVER, LEAD, IRON-oRE. NATIVE SFLPHFR. SALT. GVI'SFM, SILEHATE 

 OF SODA. SULPHATE OF MAGNESIA. NATIVE ALUM. MINERAL SPRINGS, STONE-COAL, TOPAZ- 

 GEOLOGICAL STRUCTURE OF THE SUCCESSIVE MOUNTAIN RANGES PROGRESSING FROM EAST 

 TO WEST. 



On crossing the summit of the Wahsatch Mountains, coming from the east, a sec- 

 tion of country is entered altogether different from that on the other side. Its pecu- 

 liar aspect is pre-eminently derived from a change in the geological formations, and the 

 physical features in general. It forms a part of the region which has been called 

 "The Great Basin," because it has no drainage to the ocean, as all the streams origin- 

 ating there are lost again within its limits, and which comprises all the country between 

 the Wahsatch range to the east, the Sierra Nevada to the west, the divide of the 

 waters of the Columbia to the north, and those of the great Colorado to the south and 

 southeast. 



The name "Great Basin," however, gives a wrong impression of its hypsometrical 

 condition, for the profile of the country shows that its outskirts are less elevated than 

 the central portion, which is a lofty upland, with numerous gigantic mountain ranges, 

 equaling in height the Wahsatch Mountains and the Sierra Nevada, while in the south- 

 ern portion the surrounding heights do not attain a considerable altitude. The sur- 

 face, moreover, is divided into many systems of drainage, disconnected with each other. 



This whole region, as far as it is known, seems to present similar features through- 

 out, which are only modified by the varying elevation of its sections. As other por- 

 tions of it have been described before, I may confine myself to a few remarks in re- 

 gard to its general features along our line of travel, between latitudes ;!9° and 41°, 

 from longitude 111° 25', near Weber River, to longitude 119° 41', in Carson Valley. 



The whole must be regarded not as composed of separate mountain chains, but 

 as one system one great continental swell, the relief of which has been shaped by 



