GEOLOGY OF CENTRAL SHEN-SI. 315 
The granite at Shi-t’ing-ho, although possibly derived by segregation 
from the magma which produced the rock at W6n-kung-miau, is very 
unlike it in character. As a whole it is a massive pale reddish granite of 
porphyritic texture. The phenocrysts are well-formed crystals of flesh- 
red orthoclase, 1 to 4 centimeters in length, which are frequently twinned, 
according to the Carlsbad law. ‘The matrix is tolerably fine-grained and 
consists largely of orthoclase, quartz, and several dark ferro-magnesian 
minerals. A tendency toward gneissoid structure is apparent in some of 
the exposures. 
Intrusive contacts of these granite masses with the sedimentary schists 
of the Hei-shui system were observed at several points. Between Liu- 
yiié-ho and Ir-ling-p’u the northern contact of the granite of that region 
shows a zone of evident contact metamorphism about 100 feet, 30 meters, 
wide, between an impure limestone and a flesh-gray granite of medium 
grain composed of glassy feldspar, pale quartz, and biotite. In the inter- 
vening zone the limestone is very dense and hard, and near the contact 
it contains crystals of pink orthoclase, quartz, and a little biotite. The 
rock is not schistose, however, and retains the general appearance of the 
limestone. 
South of Chang-k’6u-shi a contact of the W6n-kung-miau granite 
with the Hei-shui system was seen in the ravine west of the trail. Small 
dikes of granite extend 3 or 4 feet, about a meter, into the sediments, 
and fragments of schist occur in the granite. Near the contact the slaty 
Paleozoic rocks have been converted into dark biotite-schists. The influ- 
ence of the intrusion does not extend far into the sediments, however, 
and within less than a mile all effects had disappeared. This corresponds 
with observations near Ir-ling-p’u and indicates that the batholites of the 
Ts’in-lings have not been important factors in the general metamorphosis 
of the sedimentary rocks. 
The age of the granite in the Ts’in-ling-shan is shown by the above- 
described contacts to be less than that of the strata of the Hei-shui series; 
that is, in all probability, Post-Carboniferous. The granite at Lién-hua- 
shi, which is lithologically similar, cuts schists that we assign to the K’ui- 
chou of late Triassic or Jurassic date. While possibly not contemporaneous, 
the igneous masses throughout the Han province appear to belong to a 
single epoch of intrusion, which we are thus led to place in the middle 
Mesozoic, allowing sufficient time to elapse after the deposition of the K’ui- 
chéu to permit folding and metamorphism of the strata. The granites may 
have been intruded at the close of the deformation, but not earlier, as 
they do not exhibit its effects. 
The gabbros and related basic rocks occur in the form of dikes, fre- 
quently of large size. Some of them have suffered but little metamorphism, 
