ROCKS FROM NORTHERN AND CENTRAL CHINA. B77 
microscopic gash-veins in the feldspars,* which are well exemplified in 
this section, are additional evidence of the deformation of the original rock 
(see Plate LIV, Fig. C). Granulated edges border many of the quartzes 
and feldspars, but the bulk of the material produced by abrasion seems to 
have crystallized to form the fresh seams of quartz and microcline which 
are prominent at various points. This rearrangement of material has not 
gone far enough, however, to produce gneissic structure. 
Greenish biotite granite, No. 25.—This is merely another phase of the 
dark granites represented by the last (31). It is exposed in the rear of the 
temple of Confucius, on the summit of the T’ai-shan. 
In general it closely resembles No. 31, and evidently belongs to the 
same rock mass. As seen in the hand-specimen, however, the texture is 
finer and the different minerals are less contrasted. The feldspars and the 
biotites are evidently more decayed and the whole rock has taken on a dull 
greenish tinge. 
In the greenish granite decomposition is more advanced than in No. 31. 
Both kinds of feldspars are filled with granular saussuritic products except 
in certain areas in which recrystallization has probably taken place. Here 
there is a mosaic of quartz and orthoclase with a little microcline and albite, 
in fresh crystals. Among the biotites alteration into chlorite, epidote, etc., 
has progressed far. In general the effects of metamorphism are similar 
to those already noted for No. 31. 
It is not easy to explain the abundance of epidote and zoisite in these 
two granites. When we reflect that the feldspars are dominantly alkaline 
in composition, and that the other most abundant mineral is biotite, there 
appears to be no adequate source of calcium. We seem forced to conclude 
that the albite and the innumerable grains of epidote zoisite are alteration 
products derived from feldspars rich in lime. If this hypothesis is correct 
the rocks are not true granites, but are altered mica granodiorites. 
SINIAN SYSTEM. i 
The thick series of dark limestones and shales, which von Richthofen 
named the “‘Sinische”’ system, is widely distributed in northern China. 
They range in age from Lower Cambrian to Middle Ordovician. In Shan- 
tung dark limestones compose the greater part of the system, with an 
aggregate thickness of about 4,500 feet, 1,350 meters. The upper layers 
are massive dense limestones of brown or gray colors, but in the lower 
portions oolitic, conglomeratic, and other unusual structures are charac- 
teristic. These lower limestones are interbedded at certain horizons 
with gray and green shales, and beneath them lies a series of red shales 
and earthy limestones (Man-t’o formation). 

* For further mention of this structure see page 371 of this report, 
