420 RESEARCH IN CHINA. 
White epidote aplite, No. 70.—Similar to the last. Specimen from a 
dike 2 feet, 0.6 meter, thick, which appeared to be an apophysis from the 
gray granite porphyry (No. 68). 
This specimen differs from the last chiefly in the absence of garnet and 
in the greater abundance of little blotches of dark epidote. The trace of 
gneissic banding is even more distinct than in the last case. 
In the thin section one observes small distorted phenocrysts in the 
microgranular ground-mass of quartz and feldspar. ‘They consist of quartz, 
orthoclase, and albite. Most of these phenocrysts have not been notably 
distorted during the slight metamorphism of which the matrix bears evi- 
dence; granulation appears to have occurred locally along their edges. 
Granules of epidote and minute flakes of muscovite are distributed 
in indistinct parallel streaks. The epidotes often inclose a dark-brown 
mineral which is thought to be allanite. Rare grains of magnetite and 
brown ferruginous impurities complete the short list of accessories. 
This aplite is a porphyritic felsite which has undergone slight deforma- 
tion in the zone of anamorphism. The changes are comparable to those 
in the granite porphyries with which it is closely associated. 
TA-YANG SERIES (ALGONKIAN),. 
The Ta-yang series is of late Algonkian age. The rocks are gray 
cherty limestones with thin members of shale and quartzite. Locally 
where folding has been intense the shales are schistose, but elsewhere the 
rocks are not more altered than the overlying Paleozoic terranes. 
ROCKS OF SEDIMENTARY ORIGIN. 
CARBONATE ROCKS. 
Banded gray limestone, No. 88.—This is a typical example of the banded 
but chertless layers of the Ta-yang limestone. Specimen from the lower 
1,000 feet, 300 meters, of the formation. 
A dense clear-gray rock traversed by narrow wavy bands of dark-gray 
color. Under the microscope it appears to be composed entirely of small 
interlocking calcite grains. There are no fossils nor other peculiarities of 
structure. The layers of dark pigment which produce the banding in the 
hand-specimen existed before the rock crystallized. The crystals of calcite 
have simply absorbed them as they grew, and thus the bands pass through 
the crystals without the slightest deviation (Plate LVI, Fig. D). 
SINIAN SYSTEM. 
The Sinian (Cambro-Ordovician) system in Chi-li is so nearly identical 
with that in Shan-tung as not to require additional description. The only 
specimens in our collection came from a terrane which is believed to mark 
the base of the Cambrian in the vicinity of T’ang-hién.* 

*For a discussion of the age of the rocks near Nan-t’ang-mei see p. 140, Part I, 
