APPLETONS' 



POPULAR SCIENCE 



MONTHLY. 



SEPTEMBER, 1898. 



GEOLOGICAL WATER WAYS ACROSS CENTRAL 



AMERICA. 



By Dr. J. W. SPENCER. 



Introductio:n^. — From tlie days of early discovery, adventurers 

 and explorers have repeatedly sought for accessible routes 

 across Central America. For more than half a century engineers 

 have ransacked the dense mountain forests for easy passes through 

 which to connect the two great oceans by water or by rail. The 

 number of low passes which dissect the Cordilleras and plateaus 

 between Xorth and South America is much larger than is popularly 

 known. Indeed, there are so many deep breaks in the plateau re- 

 gions as to suggest that many of them at no distant date were water 

 ways between the Atlantic and Pacific. On account of the narrow- 

 ness of the Isthmus of Panama and the low altitude of the divide, 

 this region has been most noticed as a possible geological passageway 

 between the Antillean waters and the Pacific Ocean. But it has 

 been discovered that other water ways across the American continent 

 can be even more surely established, and that neither the narrowness 

 of the Isthmus of Panama nor the lowness of the divide form any 

 additional evidence of the late interoceanic connection. 



The early Tertiary period — the time when water connection 

 across Panama had been suggested — was so long ago that the land 

 animals have completely changed their characteristics, and even the 

 sea shells have been mostly transformed into more modern species; 

 accordingly, the time has been sufficiently long for several subsequent 

 changes in the physical barriers between the Atlantic and Pacific. 

 Indeed, geological straits across the continent have existed at differ- 



VOL. LIII. — 40 



