824 



the steep Kerbau mountain '), which consists entirely of peridotites. 

 Traces of elevated reefs are lacking in the Kerbau mountain also, 

 and if the eastern part of Moa were a little lower, this region would 

 present an aspect similar to that of Luang. Both mountains, the Gg. 

 Kerbau and the Bt. Merah would then emerge from the sea as two 

 separate islands and be entirely fringed by a broad reef. 



We feel justified in assuming that also the latter region has passed 

 through a stage of evolution like that of Luang at the present day, 

 and that it has been raised above the sea, through a slight upheaval 

 after a period of subsidence or a long stationary period, or according 

 to Dai>y through an upheaval after an appaient post-glacial subsi- 

 dence. By this upheaval also the eastern |)art of Moa was united 

 to the western part. In the latter elevated reefs are found at a 

 greater height, so that the two united islands or group of islands 

 have evidently been subject to markedly different movements. 



The island of Kisser, typified by its peculiar form, behaved 

 differently again. The more or less circular island, is surrounded on 

 all sides by a wall of coral limestone raised in several (mostly five) 

 teriaces, and broken only by a few narrow gullies, through which 

 rivulets flow towards the sea. We sighted this island only from the 

 sea; according to Verbkkk') tlie elevated reefs in the western part 

 of the island, near Leweru, reach a height of 147 m., whereas the 

 interior, where amphibolite hills prevail, presents peaks ± 240 m. 

 high. The terraced structure of the elevated reefs points to an eleva- 

 tion of the island, repeatedly interrupted by intervals of quiescence 

 or — considering the thickness of' the elevated reefs (to 80 m.) — 

 of subsidence, by which a leefcap was formed, strong enough to 

 resist erosion. 



The island of Letti presents quite a different appearance . now- 

 adays from that of Kisser, but most likely this island has also been 

 encircled by a more or less continuous girdle of fringing reefs, of 

 which at larger heights occasional remainders were left at 115,129 

 and 134 m. ') above sealevel. Here erosion has demolished the higher 

 reefs almost entirely, which — on the basis of what we observed 

 about the influence of erosion — may have something to do with 

 long and uninterrupted negative tnovements. 



Many more examples of numerous abnormal elevated reefs in the 



M H. A. Brouwer. Geologie van een gedeelte van het eiland Moa. Jaarb v. h. 

 Mijnwezen Verhandel. 1916. I, p. 39. 



'; R. D. M. Verbeek, 1. c, p. 432. 



') G. A. F. MoLENGRAAFF and H. A. Brouwer, De geologie van het eiland Letti. 

 Jaarb. Mijnwezen. 1914. Verh. 1, p. 82. 



