142 T. C. CHAMBERLIN 



After moderate submersion, no land detritus would reach it, for it 

 stood on the windward side of the Antilles and of South America, 

 as the name of the group to which it belongs implies. The only 

 deposits that could well accumulate, after this stage was reached, 

 were those of the oceanic plankton or of the benthos, if it sank so 

 deep. The life relics of a portion of the deposits supports the 

 interpretation that the island actually sank to the benthos zone, but 

 there is the alternative assumption that the benthos life and corre- 

 lated conditions were carried up to unusual levels by upwelling 

 currents about the island after it reached the stage of moderate 

 submersion. The supposition of an elevated benthos zone might 

 well seem gratuitous, or even an improbable special pleading, if 

 there were not two considerations that seem to force on the case 

 a choice between alternative special pleadings. 



1. In the common interpretation it is assumed that a portion of 

 the crust was depressed 10,000 feet or more to reach the horizon 

 of the benthos and then raised again a somewhat greater amount, 

 while the benthos horizon remained stationary. This is a special 

 pleading where all the burden is thrown on crustal dynamics. This 

 may well seem to the dynamic student as inherently improbable as 

 an upwelling of abysmal waters carrying up the benthos zone does 

 to the biological student. 



2. On the island of Jamaica oceanic beds occur which likewise 

 imply depression to at least moderate depths; but the summit 

 heights of the island do not seem to have been submerged, and a 

 similar negation seems to be predicable of Cuba and Haiti, though 

 investigation in these cases is incomplete. The summits of none 

 of these three islands seem to be mantled or ever to have been 

 mantled by oceanic deposits as is the case with Barbados; they 

 merely bear such deposits on their flanks. A special pleading that 

 would carry these down to the usual level of the benthos requires 

 a supplementary special pleading to account for the absence of 

 oceanic deposits over the upper levels generally. Careful study of 

 the whole problem is yet a thing of the future, but if this is a repre- 

 sentative picture of the case, it would seem to be in the line of the 

 least expenditure of energy and of the highest probability to avoid 

 the extremes on both sides and to assume that an upwelling of the 



