MUSEUM OF COMPARATIVE ZOOLOGY. 281 



that time. At any rate, if there had been any long epochs of subsi- 

 dence, they would be recorded in great fiord-like valleys or low passages 

 acr'oss the central axis of the island, sucl^ as do uot exist, and to which 

 the oval harbors may not be compared, for the origin of these is due 

 entirely to the pre-existing fringe reefs. 



It might be alleged that all the ancient topography showing subsi- 

 dence is still beneath the ocean level, and that the angular edges of 

 Cuba are indicative of the fact that the present outline merely represents 

 an ancient summit which is re-emerging. The submarine topography, 

 however, is not within the province of this paper, but I agree with Pro- 

 fessor Agassiz that its irregularities were indicated long before the period 

 of history herein recorded. The three alternations of gravel and reef in 

 the Matanzas section may also have indicated slight alternations of sub- 

 sidence and elevation. 



AVithout committing myself to an emphatic negation as yet, I must 

 confess that no evidences of great subsidence are apparent at present, 

 and although I hold my conclusions upon this subject in abeyance to 

 future observations, I seriously doubt its existence. 



It is now possible, with the aid of the stratigraphic and paleontologic 

 data previously given, to make a few conclusions concerning the Ceno- 

 zoic history of Cuba. It has been shown by the stratigraphy that the 

 topographic levels are not old reef levels, but that, with the excep- 

 tion of the modern reef, they have all been carved out of the old 

 Tertiary limestones, which had previously been folded and disturbed by 

 movements that could not have been generally uniform, but which were 

 erogenic, and hence the present bench topography of Cuba is subsequent 

 to this period of Post-Tertiary wrinkling, and represents a different kind 

 of movement, which was regional or epeirogenic. Since the old folding 

 or orogenic movement occupied at least a small portion of Post-Tertiary 

 time, we may reasonably conclude that the two great periods of uniform 

 uplifting recorded in the old levels must have taken place at least since 

 the beginning of the Pleistocene. In other words, they are compara- 

 tively modern in geologic time, — some of them absolutely recent. 



It is not maintained in this paper that these epochs of regional 

 elevation were continuous and uninterrupted, or unaccompanied by 

 pauses or even alternating epochs of subsidenco, but that their general 

 progress has been periodically upward, and that, if there were epochs of 

 subsidence they are difficult to distinguish, and were of short duration, 

 and insignificant in comparison with the ereat uplifting movement that 

 has generally taken place. 



