GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 281 



field study it is impossible to say which one of these views is correct, 

 but the features of the Pacific reefs that I have seen support Hill's 

 explanation." I have twice published the statement that "Hayes^ 

 Vaughan, and Spencer have shown, as is evidenced by the pouch- 

 shaped harbors of the Cuban coast and filled channels, such as the 

 submerged filled channel in Habana Harbor, that the last movement 

 of the Cuban coast has been downward with reference to sea level," 

 and that '^ the platform on which the Cuban reefs grow ^ has been 

 brought to its present position by subsidence." These remarks 

 apply to the present livmg coral reefs and not to the elevated reefs, 

 and the conditions presented by the pouch-shaped harbor is only a 

 part of the evidence showing recent submergence of the Cuban shore 

 line. 



Professor Davis's remark that "all the embayments I saw inside 

 the sea-level barriers in the Pacific occupy valleys older than the 

 reefs" has no application whatever to the protecting eft'ect a fringing 

 reef may have on the shore of a land during elevation subsequent 

 to the formation of a fringing reef, thereby permitting erosional 

 agencies to operate more rapidly on the softer rocks lying back 

 from the shore. The words in the Cuba report are: "'Wherever the 

 conditions are favorable for the growth of corals a fringing reef is 

 built * * *." 



On preceding pages of this paper I have shown that there were 

 coral reefs in Cuba in middle Ohgocene time; that there were reef 

 corals in both upper Oligocene and Miocene time (this Miocene is 

 called upper Ohgocene in the Cuba report); and that there are 

 Pleistocene as well as living reefs. In the Miocene La Cruz marl in 

 the vicinity of Santiago the greatest abundance of reef corals is not 

 at the present head of Santiago Harbor, but it is seaward of the town 

 of Santiago, east of La Cruz. (For a view seaward through the 

 mouth of Santiago Harbor, see pi. 71, fig. B.) Whether the coral 

 heads are sufficiently abundant to have retarded erosion toward 

 the mouth of the harbor, while it was more rapid on the landward 

 side, I am not prepared to say. This, however, was not a fringing 

 reef, should it be appropriately considered a reef. 



As to whether the elevated Pleistocene fringing reefs extended up 

 to the sides of the outflowing water at the harbor mouths, thereby 

 maintaining restricted outlets, or whether channels have been cut 

 across the reefs after uplift, either of the alternatives is possible. 

 Off the mouths of bays in Antigua, channels are maintained across 

 living barrier reefs, which are tied to the shore at one end; while 

 off Virgin Gorda, a barrier reef extends perpendicularly across the 

 axis of the mouth of a submerged valley. These are Uving reefs, 

 which have grown up during or after submergence and are yoimger 



I Not italicized in the original. Note use of present tense, " grow." 



