Page:Mexico (1829) Volumes 1 and 2.djvu/37

 causing considerable changes in the temperature of the more distant points.

It is not, however, to this circumstance, so much as to the peculiarity of its geological structure, that Mexico owes that singular variety of climate, by which it is distinguished from most other countries of the world.

To this I must call the particular attention of my readers, as, without a right understanding of its causes, a great part of the present sketch would prove unintelligible.

The Cordillera of the Andes, after traversing the whole of South America and the Isthmus of Panama, separates into two branches on entering the Northern continent, which, diverging to the East and West, but still preserving their direction towards the North, leave in the centre an immense platform, or Table-land, intersected by the higher points and ridges of the great mountain chain by which it is supported, but raised, in the more central parts, to the enormous height of seven thousand feet above the level of the sea.

This elevation it loses, in part, on its approach to the North, by the gradual disappearance of the Eastern branch of the Andes, which sinks nearly to a level with the ocean, about the 26th parallel of North latitude, as if to make way for those mighty rivers by which Tēxăs, Louisiana, and the Flŏrīdăs are watered: but to the West, the Cordillera continues in an almost uninterrupted line, through Dŭrāngŏ and Sǒnōrǎ, towards the frontiers of the United States, where it splits into various ramifications, until its course is lost in the unknown regions of the North.

Upon the whole of this Tableland, the effect of geographical position is neutralized by the extreme rarification of the air; while upon the Eastern and Western declivities it resumes its natural influence as it approaches the level of the sea, until the strip or belt of flat country, which extends from the base of the Cordillera to the ocean, is subject to the same degree of heat as that which prevails in the East or