254 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
ous rocks along the northernmost coast of South America and in the 
Great Antilles is directly in harmony with the east and west trend of 
the same phenomena upon the mainland," and we cannot escape the con- 
clusion that they are the product of the same great orogenic revolution, 
the age of which was Mid-Tertiary, for rocks of early and late Eocene 
age everywhere as exposed along the Caribbean coast, and in the Great 
Antilles, are folded by these mountain making processes, while the Plio- 
cene and Pleistocene are more horizontally laid down against the sea- 
ward margin of the mountain masses. 
There is a remarkable suggestiveness in the age, character, and trend 
of these late Tertiary movements with those of the Pacific coast of 
North America, especially of California and Lower Californian regions. 
An imaginative mind could easily draw a long sweeping curve along 
the Pacific coasts of Oregon, California, Lower California, and Mexico, 
across the continent in Central America and the Antilles, and state 
that it represented the trend of the great orogenic revolution of the 
Tertiary time, —a revolution which perhaps produced the greatest 
known modification of Central American and Antillean topography, and 
largely established the present shapes of the land areas. 
The Epeirogenic Movements of Роѕі- Міосепе Time.— We have de- 
scribed in detail the character of the swamp lands in the vicinity of 
Colon, composed of littoral débris of the ocean, showing that they 
represent elevation of marginal sea deposits which had been deposited 
against a greatly eroded pre-existing land. We have shown the exist- 
ence of the same phenomena upon the Pacific slope of Panama, though 
of a less marked extent. From the wide distribution of this phenom- 
enon I am inclined to believe that the whole region has undergone uni- 
form elevations in comparatively recent (Post-Pleistocene) time, whereby 
the shallow margins of the sea have been elevated into low lying coast 
lands. 
The Monkey Hill level at Panama, which rises from 50 feet at the 
sea to 100 feet a few miles inland, seems to be a widely distributed 
topographic feature. This level is the result of the degradation of the 
land down to marine base level, followed by subsequent elevation to 
its present height. This level is well defined along the Limon coast 
of Costa Rica, where are seen the same low-topped hills projecting 
above the swamp plain as at Colon, presenting exactly the same charac- 
ters of composition and topography. While I could not trace these 
1 In this connection the reader is referred to an admirable chapter on this sub- 
ject in Professor Suess’s “ Das Antlitz der Erde,” Vol. I. pp. 692-710. 
