GEOLOGY AND PALEONTOLOGY OP THE CANAL ZONE. 



611 



up before the Pliocene, and the present craters are merely secondary 

 and expiring phenomena." 



The last important shift in position of strand line along the At- 

 lantic coast of the United States and around the shore of the Gulf 

 of Mexico and the Caribbean Sea has been by submergence of land 

 areas, but subsequent to this there has been local emergence, often 

 accompanied by minor tilting or warping. 



Except vulcanism, the following table presents a succinct summary 

 of the major events considered in the foregoing remarks. It is the 

 primary intention of the present paper to characterize biologically 

 and to correlate the marine formations of the Canal Zone and the 

 geologically related areas in Central America and the West Indies, 

 and to lay particular stress upon the successive periods of emergence 

 and submergence of the land and the crustal deformation, folding 

 and faulting, concomitant with changes of that kind. Comparison 

 of the table opposite page 594, showing the correlation of the Tertiary 

 formations of Panama, with the following tabular summary, will 

 reveal that the story told by the two tables is essentially identical, 

 the erosion intervals and the marine formations in the correlation 

 table representing respectively the periods of emergence and the 

 periods of submergence in the tabular summary. 



TABULAR SUMMARY OP SOME OP THE IMPORTANT EVENTS IN THE GEOLOGIC HISTORY 

 OF THE WEST INDIES AND CENTRAL AMERICA. 



Time subdivisions. 



Events. 



Recent . 



Submergence of land areas probably resulting from deglaciation, except local 

 differential crustal movements in places producing uplift. 



Pleistocene . 



Emergence of large areas, probably due to withdrawal of water to form the 

 continental ice sheets; also oscillation of land areas by differential crustal 

 movement. 



Pliocene. 



Local moderate submergence, period of cataclysmic faulting breaking up a 

 large land area and forming the Antilles nearly as they are at present. Proba- 

 bly a narrow interoceanic connection that admitted an Atlantic fauna into 

 the present site of the Gulf of California. 



(upper 



Miocene.. \ 



middle and 

 ( lower 



[upper 



Oligocene. J middle 



[lower 



[upper 



Bocene.. -J middle 



jlower 



Extensive emergence of the land joining North and South America through 

 Central America; Greater Antilles joined to each other, and possibly to Cen- 

 tral America by bridges from Jamaica to Honduras and from western Cuba 

 to Yucatan, and to South America along the Caribbean arc. All these sup- 

 posed connections not necessarily contemporaneous. 



Extensive submergence in the West Indies and around the continental mar- 

 gins; narrow, areally limited interoceanic connections in lower Miocene 

 time, none known in upper Miocene time; land emerging in Central America. 



Extensive submergence with interoceanic connections. 



Maximum areal submergence with extensive interoceanic connections. 



Extensive submergence in Central America and southeastern United States; 



local emergence in the West Indies. 



Extensive diastrophism and mountain making by folding. 



Extensive submergence with interoceanic connections. 

 Apparently interoceanic connection across Central America. 

 Emergence of the Greater Antilles and Central America, no known interoceanic 

 connection. 



