(August, 
except that the feldspar, instead of changing into chlorite, has 
altered to muscovite and biotite, “ the result being the production 
from a completely fragmental rock, by metas omatic changes only, 
of a rock which presents every appearance of complete original 
crystallization, and which would be ordinarily classed as a genuine 
crystalline schist.” In order to show that there exists a regular 
radation between the quartzites and mica schists, Van Hise 
describes the microscopical characteristics of fine slides, begin- 
ning with a muscovitic and biotitic graywacke, with enlarged 
quartz grains of clastic origin, to a muscovite biotite schist, which 
724 General Notes. 
is apparently a typical mica-schist. A study of sixty slides shows 
that this regular gradation can be clearly traced from undoubted 
clastic rocks through graywackes to mica schists, which can not 
readily be distinguished from the ordinary schists to which a 
different origin can be attributed———The metamorphic rocks of 
California have been studied by G. F. Becker,’ and some remark- 
able results have been reached. Like the article of Van Hises 
4 referred to above, this is also an abstract of a monograph of the 
U. S. Geological Survey. It gives the results of the study of 
_ metasomatic recrystallization of the sediments to holo-crystalline 
feldsparic rocks carrying ferro-magnesian silicates and in the 
_ formation of vast quantities of serpentine. It is also clear a 
~ structural and chemical grounds that solutions rising from the 
underlying shattered granite co-operated in the metamorphism. 
d in part 
aA part aude 
alteration of the granular metamorphics. The more impo e 
st izati be traced under th 
of the clastic 
minerals are 
7. see = i 3 Ma Pa 
P npe Metamorphic Rocks of California. Amer. Jour. Set- xxx, May: 
1 P. 340. ; 
Bens Pa tits ie 7 N A Sia > oh f : n ar 
BB eae cl ee ee MORIS S een E RES eae es Pe ae a IL, IN ee ee OE ee ere ee SE POE Nee 
