400 
development of the ice-caps in the pleistocene age was attained 
simultaneously all over the earth, and that their average thickness 
amounted to 1100 m., estimated that, since the close of the pleistocene 
ice-age the sea-level has been raised by an amount ranging between 
23 and 129 m., most probably between 50 and 60 m. 
Certain accessory factors render the problem more intricate, as 
has been stated above. There are in fact still other phenomena that 
may give rise to changes in the relative position between land and 
sea and thus engender movements which either run parallel, or in 
an opposite direction to the above-mentioned. 
Among these phenomena the following have something to do 
with the glacial period : | 
1. fluetuations of the sea-level, caused by the fact that, the more 
the ice-caps grow, the more their attractive power upon the water 
of the oceans will increase, while the same will decrease again on 
the melting of the ice. This modifies the position of the sea-level all 
over the earth, but this modification is of some consequence only in 
the immediate neighbourhood of the ice-caps and there manifests 
itself by a rise of the sea-level. The corresponding sinking of the 
sea-level everywhere else on the earth, which will be most manifest 
in the regions farthest removed from the glaciated areas, is not con- 
siderable; the assumption is admissible that, during the maximal 
glaciation in the pleistocene age in the tropical seas, i.e. in the 
East-Indian Archipelago, it amounted to 10 m. or about 5 fathoms 
at most *). 
2. Fluctuations of the sea-level caused by the water being driven 
back into the oceans by the ice. In the polar regions the water of 
the sea is driven back from the coast over some distance by the 
1) This figure we borrow from Daty’s “Glacial Control Theory of Coral Reefs” 
p. 174. Daty has derived it from calculations given in R. S. Woopwarp’s “On 
the Form and Position of the Sealevel’’. Bull. 48 of the U.S. Geol. Survey 1888. 
Here, however, we do not find discussed (see note p, 78) the results obtained by 
E. von Dry@auski in “Die Geoidformation der Eiszeit’’. (Zeitsch. der Ges. für 
Erdk. XXII p. 169, 1887). In this paper von DRyGALSKY brings back to due 
dimensions the attractive influence on the sea-level of the ice-caps, accumulated in 
the ice-age on continental landmasses, which influence had been overrated hy 
Penck. It deserves attention that all these calculations have been made more or 
less based on the theory of Crorr, who held that during the glacial period only 
one of the hemispheres had been intensely glaciated, the other hardly or not at 
all (J. Crorr ‘Climate and Time” especially Chapt. 23 London 1875). It will be 
useful to make new calculations of the influence of the attraction of land-ice on 
the general form of the sea-level, based on the now generally accepted hypo- 
thesis that during the ice-age the glaciers and ice-caps have been all over the 
earth larger then now. 
