“The Central American volcanoes belong to the type that is repeated along the Caribbean shores of Colombia and Venezuela, and those in the Isthmus of Panama, and those of the great Antilles. The genesis of this American Mediterranean land-aggregate was in an independent geological impulse, and the land aggregate itself impinged by intersection upon the dominant land surfaces of North and South America. To bring together North and South America as a simultaneous geological phenomena is wrong, to make them other than an accidental geographical continuity questionable. It is this intermediate zone--the Antillean continent with lateral elongations, grasping within its continental solidarity the parallel zones of Central America and the Isthmus, that gives them terrestrial unity. Extend the axis of the Rocky Mountains, and it passes almost two thousand miles west of the coast of South America; extend the axis of the Andes and it bisects the western extremity of Cuba, and passes along the seaboard of the United States. “There is no exact geological identity here, although there is the strictest geographical homology. Each is the backbone of a continent, each upheaved and variously modified, igneously invaded sediments, derived from some pre-existent continent. They may be brought into a just comparison, but they are not strictly parts of one phenomenon. They are, however, more closely related to each other, than the Antillean areas are to either. This Antillean area, I shall here call the Columbian Continent, as the great discoverer landed at its two east and west extremities--the land-fall on San Salvador in the Bermudas, and on the coast of Honduras in Central America, as well as at Cuba, and at the mouths of the Orinoco--and his bones rested for a long time in the soil of San Domingo. It--this Columbean Continent--is a significant intercalation. It unites North and South America, but it unites them subject to the phases of its own generation.