The annexed cut shows an exaggerated profile of the country between the two oceans:
Mexico consists for the greater part of an elevated plateau having a mean height of about 6,000 feet above the sea-level. This plateau extends from the frontier of the United States to the Isthmus of Tehuantepec. It is widest in the latitude of the national capital, being about 350 miles at this point, and contracts gradually toward the south.
The principal table-lands of the northern Mexican plateau are that of Chihuahua, which lies north of latitude 24°, and east of the Conchos and Florida Rivers, and having an elevation of from 4,000 to 6,000 feet, and that of Anahuac, which is from 6,000 to 8, 000 feet high. There are four distinct table-lands on the central plateau, as follows:
| That of Toluca, having a mean elevation of | 8,570 feet |
| That of Tenochtitlan,"" | 7,470 feet. |
| That of Actopan,"" | 6,450 feet. |
| That of Istla,"" | 3,320 feet. |
Two passes, about 500 miles apart, afford an outlet from the great table-land to the eastward—viz., that of Jalapa, through which Cortes built a road during the Conquest; and one at Saltillo, through which the United States troops reached the plateau during the Mexican War.
In referring to the uniform character of the surface of the great plateau of Mexico, Humboldt has remarked in the Cosmos, vol. v, p. 380, that the traveler may proceed in a four-wheeled carriage on the ridge of the table-land, from the City of Mexico to Santa Fé, a distance of at least
