6 BULLETIN 61, U. S. DEPAKTMENT OF AGRICULTURE. 



Tlie conspicuous absence of Cretaceous formations in the basin region, excepting in 

 the Wasatch Mountains and the Iron Spring district of southern Utah,' has been noted 

 by many geologists and confirms the conclusion that the basin region was a land mass 

 in Cretaceous time. 



The pre-Tertiary was ended and the Tertiary begun by orogenic movement, accom- 

 panied by volcanic eruptions. Evidence is not conclusive as to the exact geologic 

 division, but opinion seems to predominate that the beginning of the Eocene marked 

 the beginning of Tertiarj^ volcanic activity, which extended through the Tertiary 

 and into the Quaternary. Following the early volcanic activity of this period, and, 

 no doubt, preceded by crustal movements, was the Tertiary lake period (Miocene) — 

 King's Pahute Lake. Dm'ing this period the western half of the basin region was 

 occupied by one or more lakes of great extent and irregular outline. Some parts of 

 this lake were, no doubt, of great depth, and the lake period was of long duration, 

 as is shown by the great thickness of sediments exposed in many places (notable 

 examples: Furnace Creek and the Silver Peak quadrangle). The period of lake 

 formation was also a period of vulcanism. 



A period of great orogenic movement succeeded the late Tertiary, and dviring this 

 period the basin ranges were formed and the present topography took its main outlines. 

 The Miocene lakes disappeared . The late-Tertiary is o oscure and has yet to be worked 

 out in detail for the region. King was of the opinion that the Miocene lake period 

 was succeeded by another lake period. Pliocene, but Russell has shown that, in so far 

 as the Pliocene sediments (Humboldt formation) mapped by King are concerned, they 

 belong to the LahontanLake period. Russell's conclusion is confined to the western 

 portion (Map 5, Geological Atlas, Fortieth Parallel Survey) and does not necessarily 

 include the eastern half of the basin region. Succeeding the late-Tertiary was a 

 period of erosion and continued uplift. The Pleistocene fresh-water lakes were 

 formed. The detailed study of these lakes has shown during this time at least two 

 periods of flooding and an intermediate desiccation. Fluctuations of the Pleistocene 

 lake elevations have been noted also as a conspicuous feature in the history of these 

 lakes. Glaciation in the Sierra Nevada and Wasatch Mountains coincide with the 

 period of the Pleistocene lakes. In recent time desiccation of the Pleistocene lakes 

 has taken place and minor- crustal movements have continued. 



Our inquiry has for its object thB study of saline segregates — their nature, occur- 

 rence, extent, genesis, and probable commercial utilization. The basin region has 

 always been considered a favorable place in which to look for saline deposits. The 

 prevalence of volcanic and eruptive rocks indicates a source from which salines might 

 be expected to come. The decomposition of these rocks, the solution of the salts 

 resulting, and the fact that this region possesses no outside drainage have caused. geolo- 

 ^ts to conclude that saline segregates would be found in many of the basins. There 

 IS much evidence, which wiU be discussed in a later part of tMs paper, to justify this 

 conclusion. 



Turrentine has summarized the geological formations and principal localities in 

 which saline segregates have been found. The following table indicates these: 



Geological formations and principal localities in which saline segregates have been, found. '^ 



Geologic period. 



Locality. 



Kecent . . 



Tertiary. 



Cretaceous. 



Kirghiz steppes; Arabia; South America; Dead Sea; Great Salt Lake, 

 and numerous other ancient lakes in -western United States. 



Cardona, Spain; Wieliczka and Bochnia, Galicia; Siebenbiirgen; Asia 

 Minor; Armenia; Rimini, Italy; Petit Anse, La.; California, Utah, and 

 Nevada. 



Westphalia brines; Algiers. 



Jura ' Rodenberg on the Deister; Bex in Canton of Waadt, Switzerland. 



[Keuper. 



Trias \ Muschelkalk 



I B untersandstein. 



Permian 



Carboniferous. . . 



Devonian 



Upper Silurian. 



Lorraine: Hall, Tyrol; Hallein and Berchtesgaden (near Salzburg). 



Wurttemberg; in Thuringia, Emstthall, Stottenheim. 



Hanover, Schoeningen near Brunswick, Salzderhelden; Cheshire, Eng- 

 land; Kansas and Texas. 



Gera, Artera (Thuringia); Staasfurt, Halle, Sperenberg; Segeberg (Hol- 

 stem); Kirghiz steppes on the River Heck; Kansas.^ 



Kanawha and New River, W. Va.; Durham and Bristol, England. 



Winchell, Mich. 



New York; West Virginia; Saginaw, Mich.; Goderich, Canada. 



> Bui. No. 338, U. S. Geological Survey, Iron Spring District of Southern Utah. 



* Turrentine, J. W. The Occurrence of Potassium Salts in the Salines of the United States, Bui. No. 

 »4, Bureau of Soils, U. S. Dept. of Agr., 1913. 

 " Haworth, Geol. Survey, Kansas; Aim. Bui., 1897, p. 56. Harris, La. Geol. Survey, Bui. 7, p. 94. 



