PINE VALLEY PLIOCENE. 583 



Soda 3.45 



Potassa 1.15 



Lithia trace 



Water . „ 2.64 



100.04 



One specimen from this body contained some hornblende, which was 

 apparently an accidental constituent. 



Pine Valley Pliocene.^ — In the eastern foot-hills of the range, at the 

 east base of Cortez Peak, the basaltic field is overlaid by a comparatively 

 thick deposit of lacustrine Pliocene, in all respects like the Humboldt 

 Phocene. The beds are largely arenaceous, though toward the top there 

 are fine clays, and singular beds composed of carbonate of lime and car- 

 bonate of soda in such proportions as almost to represent the composition 

 of Gay-Lussite. There is no doubt that this formation formerly filled the 

 entire area of Garden and Pine Valleys, and that the erosion of the drain- 

 ing streams has worn away a broad depression through the middle, which 

 has been filled with Lower Quaternary and Quaternary. 



On the east side of this valley, about four or five miles north of Min- 

 eral Hill, is an interesting exposure, where the Pliocene is worn into vertical 

 bluffs 40 or 50 feet in height, of rounded and pinnacle-like shapes like the 

 eastern bad-lands. The strata on this side are more calcareous than on the 

 west, and contain beds which are almost limestone, but, as far as observed, 

 are devoid of fossils. 



The locality is particularly interesting as showing the relations between 

 Pliocene and the Lower Quaternary. Usually the Lower Quaternary, 

 as observed by us, has consisted of thin beds laid down conformably over 

 the Pliocene, and occupying alkali flats, which, from their position in 

 the very bottoms of the valleys, are not cut through and eroded by the 

 streams. In this case, however, the main valley erosion took place, cutting 

 out the broad valley bottom before the deposition of the lacustrine beds or 

 Lower Quaternary, so that it occupies a position 40 or 50 feet below the 

 top of the Pliocene, and skirts the base of the bad-lands, proving that the 



^ From field uotes of Clarence King. 



