TERTIARY SEDIMENTARY SERIES 245 



and on the west by the Inyo range, the northern limit being entirely 

 unknown. Moreover, this basin may easily have connected through the 

 depression north of Lone mountains with the Ealston Desert basin, which 

 lies east of the Montezuma mountains. The beds arch up over the central 

 part of Silver Peak range, reaching an altitude of 7,000 feet at Eed 

 mountain. It is therefore clear that this portion of the range did not 

 exist in Tertiary time, and that its site was a portion of the lake basin 

 extending from the Inyo range on the west to the Montezuma mountains 

 on the east. It is also clear that this portion of the range was uplifted 

 in post-Esmeralda time. The highest part of the Silver Peak range at- 

 tains an altitude of 9,500 feet, but the highest summits are made up of 

 Tertiary lavas of later age than the lake beds. 



Basal conglomerate of the Esmeralda formation. — In the upper por- 

 tion of Ice House canyon and in the ridges to the west are narrow lenses 

 of conglomerate, often of a bright red color, containing very abundant 

 subangular but evidently waterworn fragments of green schist, blue lime- 

 stone, marble, vein-quartz, and fragments of black siliceous argillite. 

 The green schist or slate is apparently precisely like that found in the 

 Lower Cambrian, and the siliceous argillite is indistinguishable from the 

 siliceous argillite of the Ordovician. These fragments are imbedded in 

 a limestone matrix, and in this matrix there are frequently oval bodies, 

 with a maximum diameter of l 1 /^ inches, which show in section a distinct 

 concentrically laminated structure. These bodies, like the orbicules pre- 

 viously mentioned of the Lower Cambrian limestone, have been examined 

 by several paleontologists, who regard them as of concretionary origin. 

 The conglomerate lies with a marked unconformity on the Paleozoic 

 rocks. Immediately overlying the conglomerate lenses, which are perhaps 

 100 feet in maximum thickness, are basalts and other lavas. Similar 

 beds are found at the base of the Esmeralda formation, in the central 

 part of the Silver Peak range, 3 miles northwest of the summit of Ehyo- 

 lite ridge, at the head of a large ravine. Overlying the conglomerate are 

 hardened buff sandstones. 



Tertiary detrital-slope breccias.— -The low, dark hills and ridges east 

 and southeast of the south end of the Big Smoky valley are covered with 

 loose fragments of Cambrian and Ordovician limestone, quartzite, and 

 slate. A careful examination of these hills shows that they are made up 

 of coarse bedded breccias, intercalated with thin sandstone layers. The 

 beds dip at considerable angles, and farther southeast, apparently con- 

 formably overlying the breccias, are fine sediments containing fish re- 

 mains. The breccias evidently represent old detrital beds of subaerial 

 origin, and would seem to indicate oscillations of level of the waters of 

 lake Esmeralda or local uplifts and depressions. 



