MUSEUM OF COMPARATIVE ZOOLOGY. 28 



o 



that no coastal accumulations are preserved around its perimeter. This 

 elevation likewise developed the present outline of the island almost in 

 its entirety, and perhaps in greater area, jvhich has since been destroyed 

 by erosion. 



5. Following this older and greater Post-Tertiary elevation, and inter- 

 vening between it and the time of the Cuchilla, or five-hundred-foot 

 level, there was a long period of erosion, cutting down the country to the 

 Cuchilla plain, which was at that time marine base level. 



6. Renewed and general elevation of the island commenced in recent 

 time, after the period of rest recorded in the Cuchilla level. The later 

 terraces, sea cliffs, base levels, and modern coral reefs and savanna 

 deposits of the south coast were tlien elevated. It is also evident that 

 in this later period elevation was intermittent, accompanied by slight 

 pauses. It is difficult to exactly fix the time of this latest elevation. 

 It was certainly very recent, and a considerable period later than the 

 old Yunque elevation. It cannot be older than late Pliocene, and it 

 may or may not be in pi'ogress at present. 



It is not the province of this paper to discuss the history and origin 

 of the Antillean sub-continent to which Cuba belongs, but I cannot 

 refrain from presenting a few thoughts which may be of service to those 

 who may consider this subject. 



The old metamorphic floor represents, beyond reasonable doubt, a land 

 that existed probably in Cretaceous time, and much of its metamorphism 

 and igneous extrusion took place in that period. Similar phenomena 

 have been recorded in Santo Domingo and Jamaica. In fact, it is not 

 proved that any rocks older than Mesozoic existed upon any of these 

 islands. Similar disturbances and excessive vulcanism and metamor- 

 phism are known to have been extensive on the Cordilleran region of 

 the North American continent, including all of Mexico and the Cordil- 

 leran region of the United States, which have been described by the 

 writer and others, and lately most aptly termed by Lawson the ]\Ieso- 

 zoic revolution.^ 



As I have shown in a previous paper,^ the marine waters extended 

 across the isthmian region of the American continent, at least during 

 the earlier half of Cretaceous time (the Comanche epoch). Whether 

 this was by union of the two oceans, or by an eastward indentation of 

 the Pacific, or vice versa, I am not prepared to say. It is certain, how- 



1 See tlie Journal of Geology, Vol. I. No. 6, September- October, 189-3. 



2 The Cretaccotis Formations of Mexico and their Relations to North American 

 Geographic Development, American Journal of Science, April, 1893. 



