/ Rhyoli 



LA VAS IN THE CREA T BASIN REGION 631 



found in Nevada. The completeness of the section enables one 

 to see how complicated the history of Tertiary vulcanism and. 

 sedimentation is, but the following is the general succession : 



1. Biotite rhyolite. 



Rhyolite tuffs and sands. 

 f Pyroxene andesite, tuffs and breccias. 

 I Biotite-hornblende quartz-latite (basic). 

 -^ Biotite-hornblende dacite. 

 Biotite-hornblende rhyolite, and tordrillite (heavy flows). 

 Thin-bedded rhyolite (Pliocene). 

 Pyroxene olivine-basalt. 



(Pleistocene.) 

 lite-tordrillite. 



Funeral Range. — The volcanic activity of the Funeral Range 

 has not been very well observed, but the following is part at 

 least of the succession : 



1. Biotite andesite (Eocene or Miocene). 



2. Olivine-basalt. 



Panamint Range. — In the Panamint Range the following 

 succession of lavas has been observed: 



Feldspathic lavas of medium acidity ; species undetermined. 

 Rhyolite. 



2. Andesite (late Eocene or Miocene). 



3. Pyroxene aleutites and basalts, often olivine-bearing (late Pliocene or 



Pleistocene). 



Randsburg region. — In the mountains in the vicinity of the 

 mining camp of Randsburg, in southern California, the writer 

 observed the following succession : 



1. Biotite rhyolite (early Eocene ?). 



Rhyolitic tuffs and sands. 



2. Hornblende-pyroxene-biotite aleutite. 



( Pyroxene basalt 



3. J (Pleistocene.) 



/ Pyroxene olivine-diabase porphyry (dike). 



Coso Range. — According to Mr. Fairbanks, 1 the following is 

 the succession of lavas in this range, roughly stated : 



1. Rhyolites and andesites. 



2. Basalts. 



1 Am. Geol., Vol. XVI, February 1896, p. 73. 



