The region discussed in the following paper embraces northern Costa Rica and southern Nicaragua. Its special interest lies in the fact that it contains the lowest gap in the Continental divide between the straits of Magellan and the Arctic ocean, and probably also contains the most feasible route for an interoceanic ship canal.
In connection with the investigations of the canal route by the United States Nicaragua Canal Commission, the writer spent ten months of 1898 in field-work in the canal region, the greater part of which was in the direction of drilling operations. In this way much detailed information was obtained concerning the geology immediately upon the canal route, but little opportunity was afforded for a general examination of the adjacent region. The conditions which prevail over much of the country, however, especially the presence of a luxuriant tropical vegetation and the depth of rock decay, entirely prevent, . . .