HILL: GEOLOGY OF JAMAICA. 18 



9 



Beds of the Vicksburg horizon have not been discovered between 

 Yucatan and the Mississippi. Agassiz ^ lias reported the beds of the 

 Vicksburg epoch as constituting a ridge along the southern peninsula 

 of Yucatan. Orbitoidal and jS'ummulitic limestones form a belt of strata 

 in Chiapas and Yucatan back of the later marginal coast furmations. 

 A. Agassiz's observations, notwithstanding Heilprin's denial, have been 

 confirmed by the more recent explorations of Dr. Karsten, J. Felix, and 

 H. Lenk.'^ These authorities show the existence of Orbitoidal and 

 Nummulitic limestones in the vicinity of the ruins of Palenque and other 

 localities, and prove according to them the existence of marine Eocene 

 strata of the Alpine Nummulitic and Orbitoidal limestone facies in Yuca- 

 tan, Mexico. 



The only known locality of this formation around the margin of the 

 Caribbean is in the uptilted beds at Guallava, Costa Rica, 150 feet 

 above the sea, which Dall has identified from collections made by the 

 writer, as reported in my work on the Isthmus of Panama. In Costa 

 Rica at least, the Vicksburg beds are of an impure non-oceanic nature, 

 occurring as in the Antilles above igneous derived rocks. 



Although the Bowden fossils are reported to have wide extent in the 

 tropical region^ by paleontologists, the formation has not been clearly 

 defined stratigraphically. According to Dall the molluscan element 

 of the fauna is homotaxially equivalent to the Chipola, Tampa, and 

 Chattahoochee beds of Southern Florida, and occurs also in Trinidad 

 and Cura9oa. It also occurs around the continental perimeter along 

 the Carribbean side of the Isthmus of Panama, where the formation has 

 been described by the writer as the Monkey Hill beds ^ of Panama and 

 back of Chiriqui lagoon. There can be little doubt, however, that the 

 sediments of this age have considerable extent along the Talamancan, 

 Panamic, and Colombian coasts of this general Isthmian region. 



The equivalents of this formation are known in Cuba, and its fossils 

 from Haiti. It has great development along the north coast of Cuba 

 especially towards the eastern end, where it is composed of the yellow 

 clays and gravel beds called Miocene (after Dall) in the writer's papers 

 on that island/ and is well developed at Matanzas, Kuevitas, Gibara, 

 and Baracoa. I now have little doubt, in the light of later experiences, 



1 Three Cruises of the Blake, Vol. I. 



2 Neues Jahrbuch fur Mineralogie, 1895, Bd. II. pp. 207, 208. 



3 proc. U. S. Nat. Mus., 1896, Vol. XIX. p. 304. 



^ The Geological History of the Isthmus of Panama, p. 176. 

 ^ Notes on the Geology of the Island of Cuba, Cambridge, 1895. 



