﻿GEOLOGY AND PALEONTOLOGY OP THE CANAL ZONE. 581 



one of which was identified by Bagg as Orbiimdes mantelli, and is 

 definitely correlated by Hill with the Vicksburg deposits of Missis- 

 sippi. The identification of Orhiioides (Leiddocyclina) mantelli 

 is subject to doubt, and the doubt attaching thereto affects tho 

 validity of Hill's correlation. However, the fact that the Montpclier 

 limestone overlies the upper Eocene Cambridge formation and that a 

 stratigraphic break occurs between it and the Bowden marl is strong 

 stratigraphic evidence in favor of the correctness of Hill's opinion. 

 The stratigraphic evidence leads to tho supposition that the orbitoidal 

 Foraminifera belong to the genus Leindocyclina, and their having 

 been identified as Orhiioides mantelli indicates that they have tho 

 form of that species. From the available evidence I consider 

 Hill's conclusion justified, but until the Foraminifera have been 

 critically studied the correlation is only tentative. 



Hill' presents a correlation of Tippenhauer's columnar section 

 for the island of Haiti with the Jamaican formations. Tippenhauer 

 gives very m.eager information on the paleontology of Haiti, but he 

 does say that the yellow limestone, the formation overlying Eocene 

 conglomerate, contains '^ Orhiioides.'^ ^ Gabb mentions the abun- 

 dance of ^' Orhiioides'' \n Santo Domingo,^ but his statements are 

 indefinite. It will later be made clear (p. 591 of this volume) that 

 orbitoid Foraminifera are absent in Santo Domingo in deposits of tho 

 same age as and younger than the Bowden marl. The orbitoidal 

 limestones of Santo Domingo are therefore older than the Miocene of 

 Rio Gurabo, etc., and are probably of lower or middle Oligocene age, 

 although they may be of upper Oligocene ago. Additional strati- 

 graphic and paleontologic work is needed before reliable conclusions 

 on these matters are possible. 



There is at present no information that suggests the presence 

 of lower Ohgocene marine deposits in the West Indies east and south 

 of Haiti. At the base of the Pepino formation in Porto Rico and of tho 

 Antigua formation in Antigua there are erosion unconformities, 

 indicating periods of uplift during the lower Oligocene. I have not 

 been able to procure information on Guadaloupe or Martinique 

 that would serve as a basis for an opinion on the age of the lower 

 formations in these islands. 



On the island of Trinidad lower Oligocene (Sannoisian and lower 

 Stampian of Douville) ^ is well developed. 



There is no information on northern South America. 



' The geology and physical geography of Jamaica, p. 172. 



« Tippenhauer, L. G., Die Insel Haiti, vol. 1, pp. 86, 87, 1892. 



' Gabb, W. M., On the topography and geology of Santo Domingo, Amcr. Philos. Soc. Trans., now 

 ser., vol. 15, p. 96, 1873. 



« Douville, H.. Les Orbitoides de I'lle de la Trinity, Comptos Rend., vol. 161, pp. 87-92,1915; Los Orbl- 

 toides do I'lle de la Trinity, Idem, vol. 164, pp. 811-817, 1917. 



