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movements which had been present to account for the formation of the 
pliocene “graben” and ‘horsten’’.') 
During the prolonged period of recent upheaval the running waters 
were obliged to cut their courses with strong and increasing gradients. 
Narrow deep valleys, often true gullies (caüons) were formed which 
are characteristic of the topography of the greater part of the island. 
Numerous terraces are found along the courses of the rivers as well in 
connection with those rivers which have developed their systems within 
the late-tertiary basins, as also with those, where the systems lay entirely 
outside of the basins. This proves that the entire island of Timor took 
part in the recent upheaval, although not everywhere to the same extent. 
This unequal or differential upheaval of the land has caused the 
rivers which flow within the tertiary basins to generally transverse, 
somewhere in their course, one or more of the strong layers of reef- 
limestone, at those places where those are comparatively little elevated. 
Thus the Benain has, in the central portion of the Benain-basin near 
the native village Neke, at an altitude of 296 M. cut a narrow deep 
gorge of more than two miles in length through a thick stratum of 
coral limestone. In one portion of this gorge the running water 
undermined a portion of the coral limestone, and thus formed over 
the current, which is very deep and strong a natural arch or bridge 
which is now a much frequented road of communication. 
') My conclusions differ slightly from those of VeRBEEK (R. D. M. VERBEEK, 
Molukkenverslag. Geologische verkenningstochten in het oostelijk gedeelte van den 
Ned. O-l. Archipel. Jaarb. van het Mijnwezen XX XVII. Batavia 1908). According 
to VERBEEK the coralreefs of the Talau-basin are of different age, and were all 
formed during the gradual upheaval of the land as fringing reefs, which are now 
found to be the older because of their higher level above the sea (lc. p. 777). 
The highest, those of the Diroen-ridge at an altitude of 1283 M. above sealevel, 
are regarded as of miocene age, those of Lahoeroes at an altitude of 569 M. of 
somewhat later date, and the lowermost, those of Fatoe Lamintoetoe at an altitude 
of 300 M. of pliocene age. These coralreefs diverge the older they are proportionally 
more from their original horizontal position; thus the oldest show a dip of 8°, 
those which are at a lower level of 5°40’, whereas those which occur still further 
below dip only 3°50 (l.c. p. 357 and p. 778). 
Although admitting that outside of the “graben”, coralreefs of probably miocene 
age are found and that these ancient reefs occupy the highest levels now, I am 
of opinion that the majority of the elevated reefs i.e. the bulk of those which 
occur within the area of the “graben” including the Talau-basin, and also a part 
of those which are situated beyond the limits of the “graben”, were formed before 
the commencement of the latest period of emergence (upheaval) of the island of 
Timor and consequently must be of the same late-pliocene or early-pleistocene 
age; and the above mentioned, feebly synclinal and somewhat disturbed and frac- 
tured position of the reefs, which spread continuously over large distances within 
the “graben”, would be an explanation for the fact that these reefs are found 
at present in different altitudes, decreasing towards tbe central axes of the “graben”’. 
