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West-New-Guinea, from the gulf of Mac Luer to the south, on the 
Kei-islands and in various islands of the Tenimber-group, tertiary, 
late-eocene or miocene limestone and marlformations occur, which 
at these different places are very similar to each other. The rocks 
are often bituminous, sometimes they contain bands or nodules of 
hornrock. Methanegases escape from these rocks at several places, 
e.g. near the eastcoast of Groot-Kei; and as to the little new islands 
near Oet (Klein Kei-group) VERBEEK *) already supposed it to have 
appeared in the way of the mud-voleanoes along an antielinal in 
these rocks. I found a mud-spring on the island of Mitak of the 
Tenimber-group, tertiary limestones and marls occurring in the vicinity 
on the island of Laibobar, and the supposition of the escaping 
methanegases originating here also in these or in deeper seated rocks 
is not contradicted by the facts — although rather scarce — that 
are hitherto known. The mesozoice rocks, which are very numerous 
amongst the ejections of this mud-spring, might rest upon the tertiary 
rocks and e.g. might have been overthrust over them. WANNER ’) 
believes the methane-gases and the salt water of the mud-volcanoes 
in the whole Timor-Ceram-arch to originate in the flysch-facies of 
the upper-trias *). 
I will not consider here how far this supposition may be deduced 
from the fact that the mud-springs occurring in flysch-rocks, have 
ejected merely pieces of flysch-rocks. In my provisory account of 
the geology of the island of Rotti*) some difficulties arising on 
such a supposition are indicated; and without discussing the question 
of the origin of the oil here in detail, I may point to the fact that 
the relations must be more complicated than it is supposed in the 
opinion mentioned above. 
First of all the bituminous character of the flysch-rocks appeared 
to me to be a local phenomenon, which would be an indication 
that the origin of the oil must not be sought for in this formation. 
In East-Ceram numerous gas- and oil-springs are found, sometimes 
originating from flysch-roeks, sometimes from a limestone-marlfor- 
mation, which as a rule is in many points similar to the tertiary 
rocks of Western New-Guinea and the Key-islands, which have been 
DR. D. M. VerBEEK. Molukken Verslag. Jaarboek v. h. Mijnwezen 1908. 
(Scientific part), p. 527. 
2) J. WANNER, I. c. p. 149. 
3) In connection with several facts known at the Mine office, this opinion was 
doubted there before | went to the Moluccas. 
4) H. A. Brouwer. Voorloopig Overzicht der geologie van het eiland Rotti 
Tijdschr. Kon. Ned. Aardr. Gen. 1914, blz. 611. 
