STRATIGRAPHY OF CHI-LI AND SHAN-SI. 127 
north of the pass by which the main road between Wu-t’ai-hién and Tung-yii 
crosses the ridge, the limestone contains about 100 feet, 30 meters, of thin- 
bedded impure limestones and argillites, which are bright red in color. 
Outcrops of this member, when viewed from a distance, may easily be con- 
fused with those of the red Man-t’o shales, which lie at the base of the 
Sinian in the same neighborhood. 
At the northern end of this range we find red, white, and purple-gray 
quartzites, at least 500 feet, 150 meters, thick, lying upon the purple 
argillites; the relation here, as in so many other cases, is probably that 
of overthrust. The purplish quartzite contains many restricted layers 
of moderately coarse conglomerate. As exposed in cross-section these 
bodies are flat lenses and not continuous strata. Barring its consolidation, 
the deposit has a strong resemblance to the sands and gravels which are 
laid down by shifting streams. The pebbles in the conglomerate consist 
almost entirely of dark-purple quartzite with a few fragments of lighter- 
colored varieties; they are usually less than 6 inches, 15 centimeters, in 
diameter. The conglomeratic quartzite dips northward and is overlain by 
NW 


H 
1} 
Ht 

Fic. 24 (Blackwelder. Atlas sheet C I, section I I).—Tung-yu, Shan-si. Tung-yii (Algonkian) lime- 
stones. Incomplete section of gray limestone and slates associated with conglomeratic quartzite. 
a = dark-gray and purplish sandstone with seams of conglomerate; b = purple slates; c = flinty 
limestone, pink, white, and gray colors; d= hard quartz-breccia; e = gray and brown slates 
and red dolomite; f = gray flinty limestone; g = red shale and thin limestone; h = dark siliceous 
limestone. 
light-colored quartzitic sandstone, which contains a few thin seams of earthy 
limestone. This unfamiliar phase of the Tung-yii rocks probably will be 
found to lie near the base of the system. The character of the rocks and 
the position of the exposure near the margin of the synclinorium argue for 
that view. 
West of Tung-yu.—From Tung-yii westward the outcrops of this 
system are more restricted and isolated by wide expanses of the Huang- 
t’u. In the plain on the right bank of the Hu-t’o-ho an anticline of lime- 
stone of the Tung-yii group forms a low hill. The range immediately 
southwest of the Hu-t’o-ho consists of interbedded dark schistose argillites 
with reddish limestones and occasional quartzites, which we refer to the 
lower or Té6u-ts’un formation. 
The mountain spur northwest of the town contains two massive gray 
limestones included in shaly strata of greenish and gray colors (see Fig. 
25). These are apparently continuous with the rocks which form the 
