﻿264 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



reefs, at least usually show unconformable relations. Although 

 that Agassiz was aware of the unconformity at the base of the Cuban 

 Pleistocene reefs can be inferred from his descriptions, he did not 

 emphasize the stratigraphic relations: however, he does say regarding 

 the living Cuban reefs: "In Cuba they [the coral reefs] abut upon the 

 Tertiary limestone of its shores." I observed the unconformable 

 relations at Baracoa, and stated that "Upper Oligocene yellowish 

 calcareous marls or limestone are found in the vicinity of Nuevitas; 

 also at Baracoa, where they immedmtely underlie the Pleistocene coastal 

 sohorruco."^ On page 32 of the same report it is stated: "It should 

 be added here that all of the elevated Pleistocene coral reefs as seen 

 by us and aU of those recorded by those whom we consider compe- 

 tent observers, are plastered on the surface of the upper Oligocene 

 [mostly Miocene] formations, or in some instances upon older geolo- 

 gic formations." 



Unconformable relations between the elevated Pleistocene reefs 

 and the underlying Miocene limestone or marl are observable at 

 Matanzas, Habana, and Santiago. The rock in the left foreground 

 (pi. 71, fig. A,) is the slightly elevated soborruco (coral-reef rocl^;) 

 that extends into the mouth of Santiago Harbor, clearly show- 

 ing that the harbor was outlined as a drainage basin previous 

 to the formation of the particular reef now under consideration. 

 The bluf! and slopes in the bacl^round and on the right side of the 

 illustration are formed in the Santa Cruz marl. 



The known imconformable relation at the base of the Pleistocene 

 elevated reefs was the basis of inferred "subsidence of 80 to 100 feet" 

 during the Pleistocene ; this subsidence was f oUowed by elevation and 

 channeling in the mouth of the harbor; and this was followed by 

 Recent submergence.^ I have recently prepared a revised account of 

 the shore-line phenomena of Cuba, and present the following sum- 

 mary for the vicinity of Habana : 



1. Stand of land high enough for the subaerial erosion of the 

 basement of a reef that seems to be about 30 feet above sea level 

 at present, and for the outlining by erosion of Habana Harbor. 



2. Submergence in Pleistocene time to a stand about 30 feet lower 

 than at present. 



3. Emergence in Pleistocene time sufficient to permit the cutting 

 of a channel, now submerged 100 feet in Habana Harbor; the amount 

 of this emergence would be about 100-1- feet= 130 feet. 



4. Submergence, assigned to Recent time, to a depth of about 

 100 feet. 



> Hayes, C. W., Vaughan, T. W., and Spencer, A. C, A geological reconnaissance of Cuba, made under 

 the direction of General Leonard Wood, Military Governor^ p. 23. The upper Oligocene in this quotation 

 is now considered Miocene. The italicized part of the sentence is in Roman letters in the original. 



sidem., p. 34. 



