HILL : GEOLOGY OF THE ISTHMUS OF PANAMA. 155 



Fishes, and the land fauna have been analyzed to ascertain what light 

 their differentiation would throw upon the period of time when the two 

 oceans were united through the Isthmian passage, but little study has 

 hitherto been actually made of the rocks and their arrangement, of the 

 physiographic features, and of the actual testimony of the geology of the 

 region. 



On the 10th of January, 1895, I sailed from New York for Colon 

 on board the steamer " Finance." The third day out we sighted the 

 Bahamas. 



Early on the morning of the fourth day we passed close to the ele- 

 vated wave-cut cliffs and terraces of the east point of Cuba. Beyond 

 Cape Maysi we enter the waters of the Caribbean Sea. Soon we pass 

 the tall mountainous promontories of the west end of the island of 

 Hayti, first Mole St. Nicholas, and a little later the southwest penin- 

 sula. These two promontories, the Sierra Maestra range of the San- 

 tiago coast of Cuba, and the distant peaks of the Blue Mountains of 

 Jamaica, are composed of distorted sedimentary rocks, and have attained 

 their elevation by excessive folding and crumpling of the strata. 



Thus in a single day's sailing we have seen — in the Bahamas, the 

 elevated terraces of Cuba, and the Antillean Mountains — three conspic- 

 uous illustrations of methods by which land may be made to rise- above 

 the level of the sea. These processes may be epitomized as up-growth, 

 up-lift, and up- folding. The clearness and simplicity with which these 

 processes are revealed by the voyage through the Windward Passage 

 are in marked contrast to the conditions at the Isthmus, where they 

 are complicated by the presence of a fourth kind of land, made by the 

 ejecta of the great volcanic vents of past epochs. Off the southeast ot 

 Hayti and south of Cuba the island of Navassa is passed, and its topog- 

 raphy is seen to be a simple illustration of the uplift type of land as 

 shown in the bench and scarp character marking the borders of Cuba. 

 A low bench corresponding to the elevated reef or Soboruco circumscribes 

 the island. Above this rise two cliffs, 100 feet each or more, while the 

 summit is a flat mesa. This island shows that the great epeirogenic 

 movements which have elevated Cuba since Pliocene time extended as 

 far south as Navassa. How wide an area they embraced is an im- 

 portant chapter of Tropical American geology, which will be specially 

 treated in our forthcoming report on the Island of Jamaica. 



On the morning of the 17th, our ship comes in sight of the rugged 

 forest clad hills of the Isthmian land and appears to be sailing straight 

 into the Manzanilla headland. No flat surfaces, either beaches, ter- 



