38 THE ISTHMUS OF PANAMA. 



arrived at more from a general calculation, than by 

 any attempts at an accurate census. 



The physical aspect of the Isthmus is for the 

 most part mountainous and rugged. Along the val- 

 ley of the Chagres river there are, however, some 

 very excellent table lands, especially at Pena Blanca 

 and Barbacoa, which it must be almost painful for 

 a farmer to see remaining uncultivated, but more 

 particularly in the vicinity of Panama. Going back 

 from the river, the hills often rise abruptly, but sel- 

 dom to a greater height than 150 to 300 feet, and 

 are skirted by fertile plains and green savannas, or 

 narrowly divided by ravines, down which flow, du- 

 ring the rainy season, in torrents, the rapidly accu- 

 mulated volumes of water, to unite with the larger 

 stream in* the valley. The soil is mostly of red clay, 

 and does not readily absorb the falling rain, which 

 consequently is shed from the hill-sides as from the 

 roof of a house, causing that rapid rise in the rivers 

 which is so frequently noticed by travellers in this 

 country. 



It was formerly supposed that the Cordilleras ex- 

 tended uninterruptedly through the whole of North 

 and South America, being simply greatly depressed 

 on the Isthmus of Panama. But it has been shown 

 by Berghaus, Hopkins, and others, that no such 

 continuity exists. The Cordilleras of the Andes ter- 

 minate at Darien ; and the great North American 

 range probably commences near the Isthmus of Te- 

 huantepec. 



