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which we shall call henceforward the normal facies of the Kutei 
Tertiary formation, vemains nearly unchanged from the bottom to 
the top: sandstones and shales prevail greatly; coals can frequently 
occur among them: limestones and marls, which can locally some- 
times become very important, have always a littoral character. 
We give here a short scheme of the stratigraphy developed above: 
Miopliocene. Sands, loose sandstones, soft, grey shales, very seldom 
hard clays and even shales, coralligenous limestones and 
marls, often with very fine fossils, coal from peaty brown 
to dead black, Lepidocyclinae only locally in the deeper 
parts of the formation. More than 2000 im. 
Old- Miocene. Hard, grey shales, loose to hard sandstones black, 
scaly breaking glance coal (anthracite), coral limestones and 
marls with small Lepidoeyelinae. Thickness over 1000 m. and 
under 2000 m. 
Oldest Miocene and ? Oligocene. Hard, grey shales, rather pure, 
quartz-sandstones, which are thinplated in the lower parts of 
the formation, coal seams entirely or almost entirely absent, 
limestones and marls at the top with small Lepidocyclinae. 
Thickness about 1500 m. 
Even when we stick to this scheme, there remains already 
abundant room for facial modifications, which are often met with 
indeed. 
In the neighbourhood of Balik Papan e.g. banks of limestones 
and marls are entirely or almost entirely wanting in the miopliocene. 
Near Bontang they are plentiful and not bound to a definite level, 
near Bungalun they are again rare. To the West of the lower part 
of the river Sekurau littoral strata in the miopliocene are chiefly 
represented by a thick complex of coral limestones in the centre of 
the formation. 
Coal seams are further exceedingly numerous in the miopliocene 
near Balik Papan; near Bontang and Bungalun they are much rarer, 
near Sekurau again very frequent. 
Whilst with these facies modifications the general character of 
the formation remains intact, we find to the East and the North of 
the river Sekurau transitions of facies that lead us to quite different 
types of deposits. Guided by the annexed map, in which the principal 
geological structure lines of this region — the axes of the anti- 
clinals — are indicated, we shall retrace these transitions of facies 
more particularly. 
In a profile through the Sekurau anticlinal directly to the West 
