442 RESEARCH IN CHINA. 
In some of the feldspars bent lamelle are also visible. It has evidently not 
been far below the zone of katamorphism. All of the secondary minerals, 
with the exception of microcline, are characteristic of that zone. Most of 
the potash feldspars show the microcline twinning. The crystals which 
possess this feature are but little decayed and are almost free from inclusions. 
HAN RIVER DISTRICT. 
This includes most of the drainage basin of the Han-kiang in the 
southeastern portion of Shen-si province. We limit it on the north, how- 
ever, at the southern boundary of the axial intrusive granite of the central 
Ts’in-ling mountains. 
The rocks which we saw in this region are metamorphosed sedimentary 
strata, all of which probably belong to the Han system (Paleozoic and 
Triassic?), and occasional igneous rocks which have been intruded into 
them. 
HAN SYSTEM. 
The Han system consists of sedimentary rocks which have been more 
or less severely metamorphosed. They are equivalent to the Paleozoic 
and Mesozoic rocks which are exhibited in relatively unaltered condition 
in the gorges of the Yang-tzi.* 
Rocks OF SEDIMENTARY ORIGIN. 
PSEPHITES. 
Conglomerate schist, No. 134.—This conglomerate occurs in the slaty 
anthracite-bearing series in the valley of the Nan-kiang in southern Shen-si. 
Its probable age is discussed on p. 302. Specimen collected near the pass 
2.25 miles, 3.6 kilometers, NNW. of Ts6ng-kia-pa. 
Petrographic character.—A pale greenish-gray schist in which are 
embedded pebbles of quartz and probably limestone, ranging up to several 
centimeters in diameter. The cleavage, being controlled by the contours 
of the pebbles, is irregular and lumpy. The pebbles have been severely 
compressed, so that they now lie flattened and elongated in the plane of 
schistosity. The relation of this plane to the original bedding is not known. 
The schistose structure of the rock is well brought out in the thin 
section: everything is elongated in the plane of schistosity. The pebbles 
are mostly lenticular, and the matrix, although very fine-grained, is highly 
micaceous. 
The ground-mass of the conglomerate consists of finely granular quartz 
and feldspar, with flakes of chlorite and sericite. The quartz and sericite, 
intimately mingled, lie in long irreguiar streaks associated with curving 
* See Yang-tzi gorge district, p. 465. 
