1198 
CONTACT-PHENOMENA. 
Although in consequence of the fact that little roek in situ is exposed, 
not a continuous section is found from the granite area into not 
contact-metamorphie rocks, the character of the metamorphism may 
sufficiently be determined from the facts collected. 
Between the kampong Pakis and the northwestern side of the 
strip of schists, in the middle of the river, two little rocks arise, 
consisting partly of granite, partly of contact-metamorphic rocks. At 
the same place, in the right bank of the river, granitic rocks of dis- 
tinctly parallel structure are exposed. 
N 
Fig. 4. Contact of granite and schists a short distance upstream from 
kampong Pakis. 
(g = granite. S = hornfels etc. cut by apophyses of granite. 
The northern portion of the small rock I is composed of granitic 
rocks, the southern portion as well as the rock II consisting chiefly 
of hornfels with intercalated apophyses of igneous origin. The granites 
ave dark coloured; they contain much biotite and show distinctly 
parallel structure. The rocks are altered into a hard, fine crystalline 
erayish-black hornfels, showing the original schistosity of the un- 
altered sediments. Very thin layers of granitic material can be 
distinguished even macroscopically. 
Microscopically the hornfels and the intercalated granitic bands 
do not show sharp lines of demarcation. 
The granite from the northern portion of rock I consists of ortho 
clase, plagioclase, quartz, biotite, some ore, zircon and apatite. The 
feldspars form larger crystals, enclosed by a finer quartzose crystal- 
line mixture containing feldspar and other minerals. The rocks 
therefore show a more or less distinct porphyritic structure with 
a subordinate groundmass. The plagioclases belong to the andesine 
