Geology. 155 



In regard to Bermuda it raa}^ be said that since the coral rock 

 only extends about 250 feet (nearly 75 meters) below the present 

 sea-level, this is practically within the limit of the glacial contiol 

 theory, or not allowing more than 50-60 meters in change of 

 level according to that theory, would indicate a very minute sub- 

 sidence from Eocene time. Molengraaff noticing the total thick- 

 ness of the coral limestone at Bermuda of 380 feet (110 meters 

 nearly) and that 135 feet of this is now above water, assumes both 

 up and down movements of these dimensions but this is unneces- 

 sary, for that part of the limestone now above sea-level is every- 

 where remarkably and very strongly cross-bedded, indicating a 

 pronounced dune structure. It is difficult to imagine such strongly 

 inclined cross-bedding occurring on a small isolated inland except 

 by atmospheric action. No upward movement seems, therefore, 

 needed and to obtain a just thickness of the limestone deposited 

 as a marine formation the part now above water should be sub- 

 tracted from the whole, leaving 245 feet. Considering the situa- 

 tion of the drill hole on the outer edge of the island it would 

 seem to the reviewer that the atmospherically weathered deposits 

 encountered below the coral rock are most naturally explained by 

 their being the washed-down products of land-waste lying on the 

 outer slopes of the island below sea-level, that is a wave-built 

 terrace, rather than as indicating soil in place, carried under 

 by subsidence. Also the rounded forms of the pebbles in this 

 deposit indicate much wear and transport of the material. It is 

 difficult to see how over 300 feet in depth of soil could accumu- 

 late on a small island without being washed off. 



It would seem to the reviewer, therefore, that Bermuda, stand- 

 ing as it has since, at least, Eocene time, and no one knows how 

 much longer, is an example of the stability of true oceanic islands 

 rather than the reverse. 



One cannot avoid the impression on reading the paper and 

 noting expressions used by the writer like these : "From this it 

 follows that the continents must be considered as flows of salic 

 composition, floating in the sima in the same way as ice bergs do 

 in water, being submerged with about 85-95 per cent of their 

 mass," and '' the whole sima has been called by Daly basaltic sub- 

 stratum," along with similar ones, that the writer conceives of 

 the shell immediately underlying the ocean floor as being in a 

 liquid state or possessing at all events a much higher degree of 

 plasticity than the continental masses. To be sure he quotes from 

 others to support his view and seems to feel that its assumption is 

 demanded by recent researches on isostasy, but it would seem as 

 if this were pushing the idea of isostasy to a rather extreme limit. 

 It would at all events be of interest to test the hypothesis which 

 the writer has so interestingly presented by the results of what 

 recent investigations in the fields of seismology and astrophysics 

 have taught us regarding the physical properties of the outer shell 

 of the earth. l. v. p. 



