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nection with the metamorphic character no fossils were found in 
the limestone, but I can point to the fact that they appear just 
under the covering of younger volcanic material in the north- 
western continuation of the granites, diabases, gabbro, carbonic 
limestones, marls ete. in the regions of the Siboumboun mountains 
and of the Bukit Pandjang, where VerBeeK has been able to state 
the carboniferous age of the limestones by the discovery of fusulines, 
schwagerines, trilobites and other Permo-carboniferous fossils. Again, 
in other places as where these older rocks are exposed between 
younger voleanic products of the Singgalan and the Manindju area, 
limestones occur together with granites and basic eruptive rocks. 
At a short distance up the river from the landslip, porphyritic 
granitic rocks with very large porphyritic crystals of felspar are 
exposed on the left wall, the rocks near the contact in the land- 
slip showing a much less distinct porphyritic structure, the ground- 
mass being much finer granular, and the porphyritic crystals smaller ; 
larger, macroscopically visible quartz-crystals only occasionally occur 
in these rocks. Even microscopically the latter rocks appear to contain 
but comparatively little quartz and to approach to quartz-diorites ; the 
quartz-crystals are often enclosed by a large seam of a granophyric 
mixture. The felspars consist for the greater part of plagioclase ; 
zonar structure with alternative more basic and more acid zones, often 
occurs; some central felspars were determined to be labradore- 
bytownite. In the groundmass, along with quartz and felspars, calcite, 
muscovite, chlorite, ore, titanite, apatite and epidote are found. In 
connection with the comparatively small percentage of quartz, and 
the high percentage of plagioclase there is the possibility of the 
granites being endomorphically metamorphosed near the contact. 
As to the limestones which microscopically have not yet been 
examined more closely I may state here that rocks which are rich 
in contact-minerals (a.o. garnet) and garnet-rocks, occur near the 
contact. Somewhat higher up, above the landslip, we again observe 
granite in contact with grey crystalline limestone, in which macros- 
copically no contact-minerals were observed. 
The contact-relations mentioned above, may be plainly explained 
as a normal contactmetamorphism of the limestones by the adjoining 
eruptive rocks, the granites possibly being endomorphically meta- 
morphosed near the contact. 
Along the road from Kota Tua to Matour, not far beyond the 
watershed, I found similar rocks rather poor in quartz, near the 
contact with grey erystalline limestone; perhaps various rocks which 
VERBEEK brings to the diabases of the Manindju area, and in 
