198 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th ?er. 



found in all of the larger islands of the Caribbean. These 

 rocks consist of shales, limestones, sandstones and igneous 

 rocks of various types. In certain places throughout the 

 entire region, rocks of Eocene age have been identified. For 

 example, along the Mexican Gulf border, and in Jamaica, 

 Cuba, Santa Domingo, and possibly, in the Tehuantepec 

 Isthmus, rocks of this age occur. 



The Oligocene, Vicksburg stage, occurs sparingly along the 

 Mexican Gulf border, and its southernmost appearance is, 

 according to DalP in Costa Rica. Beds of this same age are 

 also reported by Hill in Cuba. According to Hill" the Barba- 

 does pteropod chert, chalks and red clay occur in Cuba uncon- 

 formably below the Bowden and he suggests that they are 

 equivalent in age to the Vicksburg. 



Resting unconformably upon all of the older formations is 

 a series of beds bearing the Bowden fauna. The unconformity 

 between the Bowden and the above described beds is a very 

 great one and the erosion interval probably represents a great 

 portion of Oligocene time, at least. Beds bearing the Bowden 

 fauna are known from the Isthmus of Tehuantepec, Isthmus 

 of Panama, Zuluzum (Mexico), Cuba, Jamaica, Porto Rico, 

 Trinidad, Windward and Leeward islands, and, according to 

 the collection of Anderson and Martin, in the vicinity of Car- 

 tagena, United States of Colombia. Upon a diastrophic basis 

 the age of the beds containing this fauna appears to be Miocene. 



Minor occurrences of Pliocene occur in the Mexican Gulf 

 border, Colombia and Yucatan, where it merges imperceptibly 

 with the Pleistocene according to Heilprin^ and others. 



Pleistocene beds are reported at several different elevations 

 on all of the islands of the Greater Antilles as well as the small 

 islands of Barbadoes, where terraces are found at an elevation 

 of 1000 feet. Pleistocene terraces occur upon both sides of the 

 Isthmus of Panama, and upon both sides of the Isthmus of 

 Tehuantepec, but no evidence indicates a Pleistocene canal in 

 either one of these portals. (See below.) Jordan* states that 

 the fish faunas of the Panamian and Caribbean are substan- 



^ Dall, W. H., in HiH's Geology of the Isthmus of Panama, Bull. Mus. Comp. Zool., 

 vol. 28, 275, 1898.. 



==Hill, R. T., Notes on the Geology of the Island of Cuba, Bull. Mus. Comp. Zool., 

 vol. 16, 253, 1895. 



3 Heilprin, A., Geological Researches in Yucatan, Proc Acad. Sci., Phila., 136, 1891. 



♦Jordan, D. S., Proc. U. S. Nat. Mus., vol. 8, 361, 1895. 



