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Geology. — “Modijications of the facies in the Tertiary Formation 
of East Kutei (Borneo)’ by Dr. L. Rurren. (Communicated by 
Prof. Dr. A. WICHMANN.) 
(Communicated in the meeting of October 28, 1916). 
The coast tract of Kutei is for a width of more than LOO km. 
occupied by a folded chain of mountains, chiefly built up by rocks of 
posteocene age. As far as it is hitherto known eocene strata occur 
only infrequently and in a tectonic connection, which has not yet 
been sufficiently explained. 
It is not astonishing that no detailed stratigraphic subdivision 
that holds everywhere without modification can be given for the 
tertiary strata building up this chain of mountains of a length of 
more than 3000 km. A rough subdivision of the Posteocene into 
three sections, which will be briefly described below, can however 
be made for the greater part of the regions. 
The oldest part of the posteocene deposits consists chiefly of grey, 
coneretionary shales. Besides these pretty pure siliceous sandstones 
oceur, which are — especially on the lower parts of the formation — 
thin-laminated. They often contain on the planes of stratification fine 
seales of coal. Very accessorily limestones are found. In the lower 
part of the formation they contain, besides small Lepidocyclinae, 
also large specimens of this species; in the higher parts of the 
formation occur only small Lepidoeyelinae. The principal characteristic 
of the formation is of a negative nature: the great scarcity or the 
absence of coal seams. 
This section, embracing the Oligocene and the greater part of the 
Miocene, is known in South Kutei to the west of the Balik Papan 
Bay. Tbe entire Pamaluan group and the bottom part of the Pulu- 
Balang group with an estimated thickness of upwards of 1500 m. 
are to be considered as belonging to this section *). 
In the neighbourhood of Samarinda the coal-free sandstones 
and shales to the West of Batu Panggal, which are free from coal, 
belong to the oldest part of the Miocene’). 
In the surroundings of Bontang and Santan only a small portion, 
valued at about 250 m, has been brought to the surface by the 
folding. 
To the south of the river Sangatta we find at about 25 km. from 
the coast a deeply folded, domeshaped anticlinal, in which more 
1) Tijdschr. Kon Ned. Aardr. Gen. (2). 38. 1911, pp. 590 et seq. 
2) Jaarb. van het Mijnwezen in Ned. Indië Techn, Adm. Ged. 1887. 
