STRATIGRAPHY OF CHI-LI AND SHAN-SI. 113 
from this it is inferred that the mineral occurs locally in thicker masses. 
These ferruginous rocks are overlain by gray phyllites and siliceous 
marble. 
Where the overthrust crosses the western tributary a somewhat 
similar association of jasper and hematite was noted in the limestone. 
It is suggested that this represents a secondary concentration of ferru- 
ginous material along the fault-plane. 
The overlying rocks in this section are hard reddish-brown and gray 
banded quartzites and siliceous marble. They are frequently more or less 
schistose and include many thin layers of sericite-phyllite and chlorite- 
schist, which were originally layers of shale. The quartzites are locally 
conglomeratic, containing large well-rounded pebbles of quartz and quartz- 
ite. The schists become a more important element northward, and the 
section finally extends into the great mass of chlorite-schist which forms 
the summit of the range. 
In the transition belt between the quartzites and the green schists 
there is a sequence from south to north consisting of schistose conglomerate 
and arkose, then a similar schistose conglomerate, arkose, and quartzite. 
All of the rocks possess a marked parallel structure, some of them being 
fissile schists, while others are banded gneisses unquestionably of sediment- 
ary origin. The repetition of the conglomerate-schist and the overlying 
arkose-schist is believed to be due to an overthrust. The succession from 
conglomerate-schist through arkose to quartzite, and eventually to the 
chlorite-phyllites is regarded as a passage from coarse mechanical sediments 
to finer ones, such as is common in sequence upward from a basal con- 
glomerate, and is considered strong evidence of an unconformity at the base 
of the Si-t’ai or green schist series. 
The conglomerate-schists consist of pebbles of white, gray, and red 
quartzites up to 20 centimeters in diameter, of vein quartz, and occa- 
sionally of granite, embedded in a matrix of green chlorite-schist and 
graywacke-schist. In this particular locality the pebbles have undergone 
severe deformation, having been crushed and elongated so that they now 
lie with their axes parallel to the general direction of schistosity. There 
are similar conglomerates, however, 4 or 5 miles north of Liu-yiian and 
elsewhere in the district, which have not been so severely strained. There 
the pebbles are sometimes fractured along planes which lie at an angle 
of about 45° to the schistosity of the matrix; some of the pebbles are still 
intact, but when examined in the microscope the quartz grains show the 
undulatory extinction, which is characteristic of strained crystals. 
Between the conglomerate-schists and the green schists lie the transi- 
tional quartzose strata. The schistose arkose is a gray quartzite, in which 
pink feldspars are abundant. In many layers fissility is prominent and 
