222 DALY. 



coral reefs must recognize it. As already noted, the presence of a wide 

 shelf or bench, a few tens of meters below sea-level, really represents a 

 criterion for crustal stability during the later geological periods, 

 generally including at least the time since the mid-Pliocene. The 

 existence of the broad plateaus, their accordant relation at present 

 sea-level, and the impossibility of explaining them by any cause other 

 than prolonged marine action, are the supreme facts emphasized in 

 this paper. The weakest element in the subsidence theory is its 

 failure to take proper account of them. 



Perfect crustal stability in the intertropical zone during the Pleisto- 

 cene and Recent periods is obviously not implied in the Glacial- 

 control theory. Ample illustration of local uplift and subsidence in 

 the coral seas has been given. Yet a comparison of Table III with the 

 charts of reef areas in general shows the exceptions to prove the rule 

 of an essential lack of important crustal deformation in those parts of 

 the ocean, since the beginning of the Pleistocene. The fact that the 

 Pliocene beds of California and other regions are strongly folded, or 

 the fact that certain continental areas have undergone considerable 

 warping since the mid-Pliocene, may incline some geologists to doubt 

 the postulate of crustal stability for the sea floor during the same in- 

 terval of time. However, a serious appeal to the diastrophic record 

 of the continents can have no other effect than to show their general 

 freedom from strong warping since the mid-Pliocene. So far as a 

 parallel between continental and oceanic areas may be drawn, it 

 merely corroborates the idea of widespread crustal quiet in the sub- 

 marine crust. As a result of studying Californian or other mountains, 

 one cannot forecast crustal behavior in the middle of the Pacific, nor, 

 from Pliocene upwarps in the Alps, can one deduce recent subsidence 

 in the Maldive-Chagos region of the Indian ocean. Dana's own theory 

 of great antiquity for the ocean basins tends to forbid such a priori 

 reasoning. 



While the Glacial-control theory fully recognized local diastrophism, 

 as well as general crustal quiet, in the coral-sea areas during late geo- 

 logical time, the Darwin-Dana theory seems to allow no place in them 

 for a stable sea-floor during the same period. If that floor, anywhere 

 in the reef regions, was not moved since the early Tertiary, the surface 

 reefs should there be much wider than in the areas supposed to be 

 sinking. No such unusual reefs are to be found in the charts. That 

 there has been no stable place in the coral seas is surely harder to 

 believe than the view that a general still-stand of the sea bottom in 

 late geological time cannot be assumed, simply because there has been 

 recent diastrophism in the continents. 



