90 The American Geologist Feb. isoo 
The study of the tremendous erosion produced by the water, 
in a mechanical way or as a solvent, on the soft rock which com- 
poses the islands leads to a belief that the outlines of the lagoons 
or sounds are due to an erosion of the same by inroads of the 
sea. It would seem to a superficial student of the geology of 
Bermuda that the erosive power of the sea must have been a 
great factor in the production of the present form of the Ber- 
mudas, but it does not seem wholly necessary to combine with 
that cause subsidence of the ocean bed. Several advocates of 
the theory of subsidence as applied to these islands admit that 
erosion has been instrumental in the formation of the contour 
of the islands, but still hold that subsidence is also an im- 
portant cause. To the writer, however, it seems more in 
accord with evidence that the present outlines of the Bermudas 
are almost wholly due to erosion and that subsidence of the 
sea floor is secondary in the formation of the present top- 
ography. It would be possible even to go farther and say that 
erosion is almost the only cause of the present diversified 
coast line of the islands. 
This agent is believed to have led to secondary modifica- 
tions in the geographical contour of such a kind as to impart 
to the islands a distant resemblance to a compound atoll, but 
in so doing has rendered evidence drawn from them as to 
causes as compared with Pacific island atolls somewhat ques- 
tionable. The factor of erosion which all admit exists in the 
Bermudas has modified the outlines, imparting to them con- 
tours similar to those of atolls of the Pacific where erosion 
has not exerted its great influence. Arguments, therefore, 
drawn from similarity of outline must take cognizance of this 
fact. The present form of the Bermudas and that of the com- 
pound atolls may be similar, but that similarity may or 
may not be due to the same cause. The fact that there is 
another cause which is amply sufficient, which is present in 
one case and absent in the other, lends color to the belief that 
to say that both are results of the same agent is after the 
nature of an assumption. Similarity of contour does not nec- 
essarily mean similarity of cause for those contours, especially 
^ Local subsidence due to falling in of undermined land masses may 
have oc(;urred and even the whole platform may have subsided — a sup- 
position yet to be deinonstrate<l — both of these undoubtedly would 
aflfect the form of the island, but the immediate cause is erosion. 
