HILL: GEOLOGY OF THE ISTHMUS OF PANAMA. LOD 
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 cireumseribes 
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- 
