F. L. Ransome — Lava Flows of California. 373 



and Brogger trachyte-andesite. But all these compounds are 

 open to objection when a name is required for an important 

 group, standing midway between the trachytes and andesites. 

 Such a name should above all consist of a single word, and 

 should be free from the undesirable connotations adherent to 

 compounds which have been variously employed. 



Referring again to the table of chemical analyses, it will be 

 seen that in columns XXII and XXIII are placed the analyses 

 of two quartz-banakites, chosen as being the nearest known 

 dike equivalents of the latites. The correspondence how- 

 ever is not quite perfect, as the two analyses show a slight 

 deficiency in lime and a small excess of alkalies as compared 

 with the mean of the latite analyses. Iddings* states 

 that the rocks of these two analyses belong to the banakite 

 series " both mineralogically and chemically, but are somewhat 

 more siliceous, having 5 to 9 per cent more silica. They 

 might properly be given specific names, but at present we pre- 

 fer "to class them with banakite, under the name qicartz-bana- 

 kite, the amount of quartz, however, being very small." 



The banakites are intermediate rocks in a similar sense that 

 the latite are intermediate. Chemically they have a rather 

 close analogy with the latter rocks, although somewhat lower 

 in silica, and thus tending through leucitic facies toward 

 the truly alkaline groups of igneous rocks. It is interesting to 

 note that Iddingsf remarks in this series the tendency toward 

 mineralogical diversity with nearly identical chemical composi- 

 tion, already emphasized in the case of the latites. 



In the succeeding columns of the table are placed the 

 analyses of some monzonites, quoted from Brogger, in order 

 to show the close relationship between these rocks and the 

 effusive latites. Washington, has already pointed out this 

 chemical correspondence in the case of his vulsinites and 

 ciminites4 and notes as well analogies with the absarokite- 

 banakite series of Iddings.§ 



Since the paper, of which the foregoing is an abstract, was 

 written, Washington's final contribution! on the Italian vol- 

 canic regions has appeared, in which he divides the rocks 

 between the trachytes and andesites into two series, — the 

 tr achy andesites and the trachydolerites, using the former term 

 in a more restricted sense than in his earlier papers. The 

 Sierra Nevada latites would fall most nearly within his trachy- 

 dolerite series, although not strictly the equivalents of any of its 



* Absarokite-Shoshonite-Banakite Series ; Journal of Geology, vol. iii, pp. 949- 

 950. 



\ Absarokite-Shoshonite-Banakite Series; Journal of Geology, vol. iii, p. 951. 



\ Journal of Geology, vol. iv, p. 832. 



| Ibid., p. 838. 



If Ibid., vol. v, pp. 349-377. 



