405 
The name of Sunda Sea is proposed here for the shallow sea between 
Malacea, Sumatra and Java on tbe one side and Borneo on the other 
side, which embraces the whole of the Java Sea and the southernmost 
portion of the China Sea. At present no one collective name 
used for these various seas, but geographically as well as genetically 
they form one indivisible whole. NrierMEYER *) applied the name of 
Sunda Shelf?) to the floor of the shallow sea between Sumatra, 
Java and Borneo, already in 1911. I agree with him, but I apply 
the name to the entire shelf which has derived its origin from the 
submersion of the majority of the peneplanized portions of the 
Sunda Land. (to be defined later on). 
The way in which the low land originated may be conceived as 
follows : 
Before the beginning of the pleistocene period, i.e. towards the 
termination of the Pliocene, what we now call the Sunda Sea was 
presumably taken up by rather low land, or by a group of islands. 
We may imagine a partly developed peneplain, covered here and 
there by a shallow sea *). 
At the commencement of the pleistocene period the sea retreated 
in consequence of the growth of the ice-caps and thus one continuous 
tract of land was formed, the Sunda Land, uniting the present islands 
of Sumatra, Borneo and Java. It was not a high land, but on an 
average it stood at least 70 m. above the sealevel. 
In the pleistocene age followed a period of prolonged erosion, 
which had become particularly active by the lowering of the 
base-level. Owing to this the pre-existing imperfect peneplain was 
greatly enlarged and perfected. Only these areas, which offered 
great resistance against erosion protruded as hills, so-called monad- 
nocks, from the great plain. This large peneplain was bounded 
on the south, the southwest and the west by the partly volcanic, 
partly non-volcanic mountain-ranges of Java and Sumatra, on the 
north and north-east by the granitie nucleus, the high sandstone- 
tableland, and the mountain-ranges of Borneo. In this broad peneplain 
probably all the water that flowed down from those two mountainous 
regions in opposite directions, collected into a few large streams. One 
of those streams must have flowed through the region where the present 
1) J. FE. NiermMever. Barrière-riffen en atollen in den Oost-Indischen archipel. 
Tijdschr. Kon. Ned. Aardr. Gen. 2. XXVIII p. 880, 1911. 
%) KRUmMMEL calls this bank the Borneo-Java shelf. Its extent is estimated by 
him at 1.850000 km? the depth of the sea at 50—100 m. Vide O. KRrüMMEL, 
Hndb. der Ozeanographie I p. 113, 1907. 
3) This supposition is not in contradiction with the known geological data. 
