806 'I'ln American Geologist. May, 1894 
ite-porphyry from the Santa Lucia mountains, in the Coast ranges of 
California. According to Prof . Lawson, all the quartzes included in 
the orthoclase phenocrj'sts of the Santa Lucia granite have a common 
orientation, with the optic axis perpendicular to the basal pinacoid of 
the host; and the feldspars have a common orientation by groups. This 
is n<>t the case with the inclusions in the rock here described. They do 
not extinguish simultaneously, nor have they any definite position in re- 
lation to tlir area of the host. 
The granite-porphyry forms a large pari of the cresl of the Sierra 
Nevada about tin- headwaters of the Tuolumne river. It has been 
noted by the writer at several points to the north of that region, but its 
relation to the biotite-hornblende-granite or to the granodiorite has not 
been studied, except near Granite lake. Mr. Beckerstates that he found 
the same relation between the urauite-porphyry and the hornblende 
granite, in the district between Highland lakesand Bluelakesin Alpine 
county, as at Granite lake, and also that, according to Clarence King, 
granite-porphyry occurs at Mount Whitney. 
BlOTITE-HORNBLEXDK-GUAXITK. 
The biotite-hornblende-granite or hornblende-granitite, as 
it might be called, has a higher percentage of potassa, and less 
lime, than is normal with the granodiorite ; and as its relations 
to that rock have not yet been carefully studied, it is here 
given a separate description, although it is part of the great 
granite area of the Yosemite valley which has there been called 
granodiorite. 
Concretions or segregations in ih< biotite-Jwrnblende-granite. There are 
numerous nodules or schliere, as they have been called by German 
writers, in this biotite-hornblende-granite about Granite lake. These 
are particularly abundant on a vertical bank of granite a little west of 
Granite lake. The bulk of the rock is the biotite-hornblende-granite 
(No. "240 Tuolumne county), and both the biotite-hornblende-granite 
ami the schliere (No. 239) are cut by dikes or pegmatitic veins of a 
coarse granite (No. "211). The nodules are composed of feldspar in pari 
polysynthetically twinned, brown-hornblende, and brown mica. There 
appears to be also a little orthoclase. 
Very similar nodules have been described by Arthur Phillips* from 
granite in the British isles, ami by Prof. <;. P. Merrill? from the granites 
of Maine, but in neither case are the constituents of the nodules alto- 
gether the same as the constituents of the Granite lake nodules. 
Both Profs. Merrill and Phillips consider these nodules to be of concre 
tionary origin and that they do not represent inclusions of foreign rocks 
altered b\ metamorphism. 
According to F. von Adrian, as translated in Prof. Phillips' paper (p. 
*Quart. .lour. (ieol. Soc. Loud., vol. 36, pp. 1-22. 
fProc. U. S. Nat. Museum, vol. vi. pp. 137-141. 
