425 
retreat of the pleistocene ice-caps, it has been possible to conclude 
that this retreat did not proceed continuously, but was interrupted 
by periods of stability and probably also of temporarily renewed 
growth of the ice. In historical times the same thing took place; the 
glaciers of the Alps were from the Roman era down to the last 
decades of the 16' century smaller than at this day, subsequently 
their area increased rapidly, and they generally remained more 
strongly developed than is the case now until about 1850; after this 
date they have almost continually decreased, but they are not by 
far so small now as, say, in the year 1570. These facts concerning 
the extension of the Alpine glaciers in historical times, points at least 
to one very marked oscillation, viz. slight extension between + 50 
A. D. and 1570; greater extension from 1570 to 1850 and once 
more less extension after 1850, which decrease is still continuing 
There is no reason for surmising that these fluctuations should not 
have manifested themselves in a similar way on all glaciated areas 
of the earth, and if this is the case they must have been reflected 
by corresponding slight oscillations of the sea-level. It may be 
accepted, ‘therefore, that also at the coasts of the Sunda Sea 
something of such oscillations will be visible. Indeed, from 
some geologically well-known parts of the Sunda Sea phenomena 
have been observed which point to a slightly higher sea-level in recent 
geological time. Verbeek records that at the coasts of Billiton’) and 
on the surrounding islands here and there elevated coralreefs are found, 
which, however, do not lie higher than 1 or 2 meters above high- 
tide level, and are often covered by coral-débris and sea-sand. According 
to Verbeek the same occurs on the island of Banca’), while he 
adds also for this island that he knows of no places where coral- 
reefs are upheaved more than 1 or 2 meters above high-tide level. 
The position of these coral-reefs (the sea-sand proves nothing, as it 
may have been blown up by the wind there) proves that in 
comparatively recent time a slight oscillation of the sea-level has taken 
place, during which time the sea-level must have stood 2 meters, or 
somewhat more, higher than now. CoRNETS Dm Groot’) believes that 
after the Tertiary the whole island of Billiton was uplifted some 
meters, because sea-shells have been found there of late-pleistocene 
1) R. D. M. VERBEEK. Geol. beschrijving van Bangka en Billiton. Jaarb van 
het Mijnwezen XXVI, 1897 pg. 81. 
5) R. D. M. VERBEEK. l.c. pg. 62. 
3) Corn. DE Groot. Herinneringen aan Blitong. ’s Gravenhage 1887, p. 200. 
208 and especially p. 470 — 478. 
