630 J. E. SPURR 



Ralston Desert. — According to observations made by the 

 writer, the succession of lavas in the Ralston Desert is as fol- 

 lows : 



1. Rhyolite and tordrillite 1 (earlier). 



2. Rhyolites, often glassy (late Pliocene). 



3. Olivine-basalt (Pleistocene). 



Practically the same succession is seen in the Kawich Range 

 and in the Reveille Range. 



Lake Mono Basin? — In the basin of Lake Mono, according 

 to Professor Russell, we have extensive Pleistocene volcanic 

 activity, the lavas being basalt, hypersthene andesite verging 

 on basalt, and rhyolite. Older than these is a hornblende ande- 

 site. The succession in this basin is, then : 



1. Hornblende andesite. 



2. Basalt, hypersthene andesite verging on basalt, rhyolite. 



The relative age of the lavas under 2 was not determined, 

 but they are all regarded as Pleistocene. 



Toyabe Range. — In the southern end of the Toyabe Range 

 the known succession of Tertiary lavas is as follows : 



1. Biotite rhyolite (closely associated and perhaps contemporaneous 



with intrusive biotite granite). 



2. Augite basalt (Pleistocene). 



ScJiell Creek Range. — In the Schell Creek Range, near 

 Schellbourne, we have the following succession of lavas : 



1. Biotite rhyolite (flows often glassy). 



2. Pyroxene aleutite (probably late Pliocene). 



Egan Range. — In the Egan Range the following lavas 

 were found : 



1. Dacite-andesite. 



2. Basalt. 



Meadoiv Valley Canyon. — In the Meadow Valley Canyon 

 (southward from Pioche) we have one of the best exposures of 

 Tertiary lavas and their associated sediments which has yet been 



: See Classification of Igneous Rocks according to Composition, J. E. Spurr, Am. 

 Geol., April 1900, p. 230. 



2 Quaternary History of Mono Valley, California ; Eighth Ann. Kept. U. S. Geol. 

 Surv., Part I, p. 374, 379, etc. 



