482 REVIEWS 
chief reefs here are on the Kalu-Kalukuang bank, 98 by 58 km.; on the 
several Laars banks, about 65 km. in total length; on the Postillion 
bank, 140 by so km.; and on the Paternoster bank, 115 by 26 km. 
The 4o-fathom depth of the bank margins is ascribed by Molengraaff, 
following Daly’s Glacial-control theory of coral reefs, to abrasion during 
the Glacial epochs of lowered sea-level, particularly to the phases of 
rising sea-level; but it may be more plausibly ascribed to wave-and- 
current aggradation with reference to normal sea-level in post-Glacial 
time, as above suggested. For even if a bank so or more km. in diameter 
were cut away by the waves during the lowered stand of the ocean in the 
Glacial period, its margin ought to have been at least 20 or 30 fathoms 
below the sea-level of that time and hence not 40 but 55 or 65 fathoms 
below present sea-level, with a gradual shoaling toward its center. 
Departures from such a form should therefore, under the explanation of 
the banks by abrasion, be accounted for by post-Glacial reef growth and 
submarine aggradation. In any case, it would appear that, if no dis- 
turbance takes place, these imperfectly reef-rimmed banks will in time 
develop into typical atolls of large size. 
W. M. D. 
Atollen in den Nederlandsch-Oost-Indischen Archipel. De Riffen in 
de Groep der Toekang Besi-Eilanden. (Atolls in the Dutch East 
Indies.) Door Dr. B. G. EscHer. Batavia, Java: Mededee- 
lingen . . ... Encycl. Bureau, Vol. XXII, 1920, pp. 7-18. 
There has been discussion for some years past among the geologists 
of the Dutch East Indies as to the occurrence or absence of true atolls 
in their archipelago. Although atolls are certainly rare in that region, 
the occurrence of several typical examples is made clear by Escher, who 
had opportunity in March, 1919, of examining several reefs in the Tukang 
Besi group, southeast of Celebes. A copy of the original survey of the 
islands by the Hydrographic Service of the Dutch East Indies on a 
scale of 1:200,000, containing a greater number of soundings than those 
represented in the chart published for the use of navigators, is reproduced 
in Escher’s paper. It shows seven atolls, the smallest about 2 km. in 
diameter; the largest measuring 48 by 15 km. and inclosing a lagoon 
15 or 20 fathoms deep. Escher points out that these atolls le in two 
belts, trending northwest-southeast, 100 or 130 km. in length, and that 
between the two belts and to the northeast of both of them are two 
roughly parallel belts of high islands bearing raised reefs, with fringing 
reefs at sea-level. The overall breadth of the four belts is about 140 
ony ree 
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