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VERBEEK supposes*) that Archean as well as old-Palaeozoie rocks 
occur among them. But, for reasons, which have been expounded in 
other papers we feel justified in assuming that these rocks — in 
part at least — are of younger date. *) 
When confining ourselves to the island of Timor, the available 
data seem to bear out that the older massifs, constituting the base 
of the Tethysgeosynelinal, have not, at all events not here, been 
raised sufficiently by the folding process to be denuded through the 
erosion, to which that portion of the overthrust mountain range 
that had been lifted up above the sea-level, was exposed for a long 
time. 
This must have been the case also in an earlier stage in the 
region of the Alps, when in the middle-mesozoic period the Tethys- 
geosyncline was divided into different geosynclines and geoanticlines, 
with partial emersion of the latter. 
Prolongation of the curve west of Timor and west of Ceram. 
The island of Roti may be considered as a direct continuation of 
Timor; we find there rocks of the same kind and various facts 
point to a similarity in the tectonic structure®). Similar rocks are 
also found in Savu, but Sumba presents a totally different structure; 
not a vestige of the intense miocene foldings is found here. That 
the prolongation of the overthrust mountain-range does not proceed 
over Sumba is not surprising in connection with the contour of the 
“Vorland”. South of Timor the limit of the Australian block bends 
southward, so that Sumba lies further from the ‘‘Vorland” and 
consequently assimilates itself more to the more northern row of 
the Sunda islands. 
With respect to the prolongation of the curve west of Ceram 
Martin believes that vast overthrusts possibly also occur in Buru‘). 
The elliptical “belt of ancient rocks” indicated by VrrBerK on 
Plate | in his Molukken Verslag, diverges from Buru in south- 
RD. M. Verpeex. Molukken Verslag, loc. cit, p. 738. Verslagen der Afd. 
Natuurk. DI. XXV, 1916/17. 
5 Comp. H. A. Brouwer. Geologisch Overzicht van het oostelijk gedeelte van 
den Oost-Indischen archipel. Jaarboek Mijnwezen in Ned.-Indië. 1917. Verh. Il, 
p. 33—35. 
Devonian rocks with Spirifer Verneuili occur in Celebes (H. A. Brouwer. 
Devonische afzettingen in den Ol. archipel. De Ingenieur. 29 Nov. 1919). 
*) H. A. Brouwer. Voorloopig Overzicht der geologie van het eiland Roti. 
Tijdschr. Kon. Ned. Aardr. Gen. XXI. 1914, p. 611. 
OL G. A. . Morgraraarr. Verslag betreffende de wenschelijkheid etc. 
Tijdschr Kon, Ned. Aardr. Gen. XXXL. 1914, p. 369 ff. 
51 
Proceedings Royal Acad. Amsterdam. Vol XXII. 
