Four peaks—viz., Popocatepetl, Iztaccihuatl, Orizaba, the Nevada de Toluca—rise above 15,000 feet; and three others—the Cofre de Perote, Ajusco, and the volcano of Colima—are upward of 11,000 feet in altitude. (The exact heights of these mountains are given in Part II.) Referring to these lofty peaks, Humboldt remarks:[1] “On the great table-land, the colossal mountains covered with perpetual snow seem, as it were, to rise out of a plain. The spectator confounds the ridge of the soft swelling land, the elevated plain, with the plain of the lowlands, and it is only from a change of climate, the lowering of the temperature under the same degree of latitude, that he is reminded of the height to which, he has ascended."
The country is divided into three zones—viz., the tierra caliente, or hot land; the tierra templada, or temperate land; and the tierra fria, or cold land. About one half of the surface of Mexico lies in the latter zone, the remainder of the Republic being almost equally divided between the tierra templada and tierra caliente. Geographers differ in defining the limits of the various zones, as is shown by the following table:
| ZONES | According to Humboldt. | According to Milner. |
| Tierra caliente | Up to 3,9.36 feet. | Up to 2,000 feet. |
| Tierra templada | Up to 7,217 feet. | From 2,000 to 5,000 feet. |
| Tierra fria | Above 7,217 feet. | From 5,000 to 8,000 feet. |
The coasts of the Republic are low, but the land rises gradually upon going toward the interior. The flat region of the eastern part of Mexico is wider than that of the western coast. In the former the tierra caliente has an average breadth of about 65 miles, while in the latter it varies from 40 to 70 miles.
- ↑ Cosmos, vol, V, p. 379.
