JOURNEYS THROUGH KOREA. 75 



in the porpliyritc-tuff, from which fact \vc can estimate the 

 young age of the granite. 



Koang-jyu '^ 



Koang-jiju (60 m), the magisterial town of South Chg'ôl-la-Do, 

 is located in the basal granitic hollow and on the talus slope of 

 the overlying porphyrite- sheet of Mu-teung-san already mentioned 

 (PL XL fig. 3). On the north and south, the town is closed in 

 by offshoots of the green effusive ^^ of Mu-teung-san which over- 

 hangs the eumnal on the east (PL XII. fig. 2), and sends streams 

 trickling down to the low open valley of the Yöng-san-gang 

 river (PL Xil. fig. 1). 



From the cumnai we took the northern route to Tain-ijang'^\ Koang-jyu 

 and on the way we crossed two east-west . hill necks of 

 biotite-granite capped with green porphyrite. After walking 10 

 km, we reached the small ilat of granitic sand of Steui-tari*^ 

 when the road divides, one branch leading eastwards along a 

 dry valley to Nam-phj'àng where the sheet of prophyrite of Mu- 

 teung-san seems to come to an end. We, however, rode straight- 

 forwards towards the north on the granite terrane which was soon 

 replaced by small whitish eye-gneiss. The latter continues to 



1) % m - ^ mm M^m m m ^ m 



2) This rock is greeuish and aplianitic with black spots. Under the microscope it is seen 

 to consist of lath-shaped plagioclase elongated along the a-axis and simply twinned after the 

 albite law, and of short prismatic, light-green diopsidic augite with tolerably high inter- 

 ference-colors and twin structure. The augite shows one axial pole on the base. It alters, as 

 enstatite does, into a greenish fibrous substtmce. Chloritic substance fills up the interstices of 

 the feldspars and causes the rock to appear macroscopically green. Clumps of ilmenite are 

 abundant altering into leucoxene. The rock is aujite-porphyrite. 



3) -W m 



4) ?F m 



