IO2 RESEARCH IN CHINA. 
suggest a sedimentary origin. The advanced condition of metamorphism 
in the whole complex made it impracticable in a brief survey to ascertain 
whether the prevailing gneiss was formerly a granite intruded into older 
sediments, or was an ancient gneiss on which were deposited the sediments 
that finally became schists and marble, or is itself a portion of a sediment- 
ary series. 
Gneisses along the Sha-ho.—The gneissic rocks exposed along the Sha-ho 
and its numerous tributaries, from the village of Wang-k’uai-chén west 
to the Great Wall, are in general similar to those near T’ang-hién. In 
texture and mineral constitution the prevailing gneiss is the same, and it 
likewise includes the lenses of amphibolite and parallel sheets of acid 
granitic material, such as we have already described with reference to the 
rocks of the T’ang-hién district. 


9° ‘ 2 MILES 

Fic. 18 (Blackwelder).—Fou-p’ing-hién, Chi-li. Detail of T’ai-shan complex showing variations in the 
gneissic rocks. a= coarse gray augen-gneiss; b = hornblende-gneiss; c = dikes of granite-porphyry 
in banded gneisses; d = brown granite-porphyry; e = hornblende-schist; / = gray biotite-gneiss; 
g = alternate hornblende- and mica-gneisses; h = granite-porphyry; 7 = fine-grained biotite- 
gneiss. 
Intrusives in the ancient gneisses.—Although obviously younger than 
the gneisses and schists, the numerous igneous rocks intruded into the com- 
plex are not easily dissociated from it (Fig. 19). They group themselves 
roughly as granites, aplites, granite-porphyries, feldspar-porphyries, and 
altered basic rocks classed as greenstones. 
Rr 
ie ts gee b AB. 
WN WL oe 2 \ Gh 
* 
” 4/77 SOM 
1000 FEET 4 

Fic. 19 (Blackwelder).—T’ang-hién, Chi-li. Detail of T’ai-shan complex (Archean), showing massive 
gneiss cut by a variety of dikes of different ages. a= brownish hornblende-gneisses cut by aplite 
dikes; b = gray granite-porphyry dikes; c = hornblende-porphyry sheets; d = schistose green- 
stone; e = amphibolite. 
Gray biotitic granite-porphyry occurs in dikes 2 to 15 feet, 0.6 to 4.5 
meters, in breadth in the mountains near T’ang-hién; it is often distinctly 
bluish on fresh surfaces, a handsome rock which the Chinese utilize largely 
in the manufacture of mill-stones. Several miles north of Ning-shan, a 
black and white hornblende-granite of coarse texture was found in the 
float, but the main body was not observed and no other occurrences were 
