626 /. E. SPURR 



The hornblende andesite of Eureka is correlated with the 

 hornblende-mica andesite of Washoe, while the pyroxene-horn- 

 blende andesite of Washoe is supposed to belong to an earlier 

 period, not represented at Eureka; otherwise the succession of 

 lavas at the two centers of eruption is considered to be similar 

 and the different extrusions in general contemporaneous. 



Sierra Nevada. — -Mr. H. W. Turner 1 published in 1895 a 

 resume of the age and succession of igneous rocks in the Sierra 

 Nevada. According to him the succession of the Tertiary vol- 

 canics in this region is as follows : 



Rhyolite — massive and fragmental. 

 Older basalt — always (?) massive. 

 Hornblende-pyroxene andesite — chiefly tuff 



and breccia. 

 Fine-grained pyroxene andesites — massive 

 Doleritic basalts — massive. 

 Other basalts — massive. 



In 1898 Mr. F. L. Ransome 2 published a critical sttidy of a 

 portion of the western slope of the Sierra Nevada, in the Sonora 

 and Big Trees region — a locality, it may be noted, much nearer 

 to the Washoe district than the Washoe is to Eureka. Mr. 

 Ransome succeeded in classifying more accurately than had 

 hitherto been done some of the intermediate lavas, determining- 

 rocks that had previously been classified variously as basalts, 

 trachytes and andesites as belonging to the monzonitic family, 

 intermediate between the granitic and dioritic families. For the 

 volcanic variety of monzonite he proposed the term " latite." 

 The succession of the Tertiary lavas in the region studied by 

 Mr. Ransome is as follows : 



1. Biotite rhyolite. 



Rhyolite tuffs. 



2. Olivine-basalt. 



3. Hornblende-pyroxene andesite brecca. 



'Jour. Geol., Vol. Ill, No. 4, May-June 1895. 



2 Bull. 89, U. S. Geol. Surv. Also Amer. Jour. Sci., May 1898, 4th series. Vol. V, 

 P- 355- 



