GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 597 



areas is discussed in the reports mentioned, which I hope may, 

 within a few months, be submitted for publication by the Carnegie 

 Institution of Washington. 



The discussion of the age and geographic distribution of the differ- 

 ent geologic formations on preceding pages partly prepares the way 

 for an account of the paleogcography of the region under considera- 

 tion;' but before proceeding the geographic relations of the Three 

 Americas should receive attention. 



Geographic Relations op the Three Americas. 



This subject has attracted many investigators, some of whom con- 

 sidered only segments of the perimeters of the two American seas, the 

 Caribbean Sea and the Gulf of Mexico, while others considered the 

 relations between Central America and the West Indies to the continent 

 of North America, on the north, and to the continent of South America, 

 on the south. Some of the important facts in the alignment of the 

 West Indies were recognized so long ago as 1848, for Schomburgh * 

 called attention to the fact that in the Lesser Antilles there are an 

 outer and an inner group of islands, the outer largely composed of 

 calcareous rocks, the inner composed of volcanic rocks. Knowledge 

 of the geographic and geologic relations within this region has grown 

 gradually, and there have been so many contributors to it that no 

 attempt will be made to credit each of them for what he has done. 

 However, special acknowledgments should be made to R. T. Hill for 

 his investigations in a number of the West Indian and Central Ameri- 

 can areas; to Carl Sapper for his exploration in Yucatan, Tabasco, 

 Chiapas, Guatemala, parts of Honduras, and San Salvador; and to 

 Karsten and Sievers for their work in northern South America. The 

 footnotes 2 below gives the titles of some of the more important 

 publications, and they contain references to earlier literature. 



i Schomburgh, Sir R., History or Barbados, p. 532, 1848. 



s Dollfus, A., and Mont-Serrat, E. de, Voyage geologique dans les republiqucs de Guatemala et de 

 Salvador, pp. 535, 18 pis., 1808, Paris. See particularly pp. 250-258. 



Felix, J., and Lcnk, II., Ueber die tektonisehen Vcrhiiltnisse der Republik Mexiko, Deutsch. gcolog. 

 Gesellsch. Zeitsch., vol. 44, pp. 303-323, pis. 19, 20, 1892. 



Ui 1, R. T., Fundamental geographic relations of the Three Americas, Nat. Gcog. Mag., vol. 7, pp. 

 175-181, 189G; The physical geography of Mexico [Abstract], Eighth Intemat. Geog. Cong. Rept., pp. 

 765-7G6, 1905. (See also papers by Hill listed on p. 604, this volume.) 



Karsten, Hermann, Geologic de 1'ancienne Colombie bolivarienne, Venezuela, Nouvellc-Grenaide et 

 Ecuador, pp. 02, 1 map, 8 pis., 1886, Berlin. 



Sapper, Carl, Grundziige der physikalischen geographic von Guatemala, Petermanns Mitteil. Ergiin- 

 sungsbd. 24, Ergiinzungsheft 113, pp. 59, 4 maps, 1894; La geografia fisica y la geologia de la peninsula de 

 Yucatan, Mexico Inst, geolog. Bol. 3, pp. 57, G pis., 1890; Das nordliche Mittel-AmeriUa, pp. 430, 8 pis., 

 1897, Braunschweig; Mitteiamerikanische Reisen und Studien aus den Jahren 18S8 bis 1900, pp. 420, 4 

 statistical tables, 4 maps .and numerous unnumbered halftone figs, and pis., 1902, Braunschweig; tiber 

 Gebirgsbau nnd Boden des siidlichen Mittelamerika, Petermann's Mitteil., Ergiinzungs Bd. 32, Ergiin- 

 zungsheft 151, pp. 82, 4 pis., 1905. 



Sievers, W., Karten zur physikalischen geographic von Venezuela, Petermanns Mitteil., vol. 42, pp. 

 125-129, pi. 10, pp. 149-155, pi. 11; pp. 197-201, pi. 15, 1890. 



Suess, E., Les Antilles, La face de la terre (translated under the direction of E. de Margerie), vol. 1 

 pp. 724-737, 1897. 



