888 The American Geologist. June, 1896 
tite and feldspar phenocrysts and microlitic fragments in a 
brown, glassy ground mass: one large grain of iron oxide was 
noted. The partial chemical analyses of these rocks indicate 
that they both may be trachytes. Koeks exactly similar to 
these were collected by Mr. K. L. Haiisoiiic and the writer in 
the ridge south of Highland creek near the east border of the 
Big Trees sheet and to the west of the Dardanelles. At one 
point at least they overlie andesite tuffs, but at other points 
appear to be covered by andesite tuffs, so that it would ap- 
pear that there were trachytic eruptions during the andesitic 
period. 
This preliminary notice of the above syenitic rocks seems 
warranted on account of the economic interest attaching to 
some of the occurrences and also on account of the unusual 
nature of some and the rarity of all of them in the Sierra 
Nevada. 
The analyses of Nos. 30 Amador, 165, 725, 1521, \')'1'1 and 
1523 Sierra Nevada collection were made by Dr. H. N. 
Stokes of the U. S. Geological Survey; Nos. 219 Plumas, 352 
Plumas and 452 and 1639 Sierra Nevada collection by Mr. 
George Steiger; and No. 455 by Dr. Hillebrand; Nos. 85, 86 
Tuolumne county and 882 Sierra Nevada by Dr. Peter Fire- 
man, of the Columbian University of Washington. 
The analyses of the soda-granites and of the soda-granite- 
porphyry are included in the table of analyses of syenite? as 
a matter of convenience, although obviously they are not 
syenites. 
Analysis 1420 S. N. is of a trachyte or a trachyte tuff from 
the Big Trees district, from an area three and three-fourths 
miles southwest of Clover Valley, Tuolumne county. Included 
in this fragmental-looking lava there are sometimes minute 
glassy black particles resembling lignite, and these are pre- 
sumably responsible for the carbon shown in the analysis, 
which is by Dr. Hillebrand. No. 1420 is very similar to No. 
85, and like it contains biotite, which is wanting in the sup- 
posed massive trachyte No. 86. 
