MEXICO. 406 MEXICO. The dry and sandy pc'ninsula of Lower Cali- fornia, the most remote region of the Republic, is also traversed by a range of mountains, broken in two places, and culminating in ilount Santa Catalina, rising 10.000 feet above the sea not far south of the neck of the jieninsula. Owing to its excessively dry climatj- and scanty population, this peninsula is still little known. The liuge quadrilateral peninsula of Yucatan is projected beyond the continental coast line toward Cuba, has no mountain ranges, and its mean altitude is scarcely above 100 feet. llYimotiR.vpiiY. The form of the central plateau, henuiied in by border ranges parallel with the sea and preventing wet winds from reaching the interior, is not favorable to the development of large fluvial systems. Xo Mexi- can river i.s important for its volume or is valuable for commerce excepting to a very limited extent. All rivers tributary both to the Gulf of Mexico and the Pacific are obstructed by sand bars at their mouth. The longest river is the Rio Grande, which rises in Colorado and for 7.50 miles forms the boundary line between the United States and Mexico. The waters of its upper course are so far diverted for irrigation purposes that the lower river is almost entirely dry dur- ing the dry season. While the Mexican jiart of its basin comprises 94.000 s(|uare miles, the river receives scarcely any jiercnnial stream. Its largest aflluent in Mexico is the Rio Conchos, which is fed for 200 miles north and south by the eastern slope of the Sierra Madre Occidental. The Salado tributary comes from the Sierra Madre Oriental, and its name. Salt River, indi- cates that its waters are rendered saline by their very slow passage through shallow basins. Other tributaries have the same peculiarity, so that they give a brackish taste to the waters of the Rio Grande itself. The I'iinuco. the most con- siderable river of the south tributary to the tlulf of Jfexieo. rises north of the Mexican 'alley and empties at the port of Tampico. The Coatzacoal- cos, or Snake River, drains the alluvial plain and low mountain district, forming the northern slope of the Isthmus of Tehuantepec; small boats as- cend it for over sixty miles from its mouth. The most important rivers on the Pacific coast are the Rio de las Ralsas (river of the rafts), which, as its name indicates, is navigable to a limited extent in its lower reaclu's, and the Lerma or Santiago, which rises a little west of the City of ^lexico. and about fifteen miles from Guadalajara is precipitated over the great falls of .Tuanacat- lan. one of the finest waterfalls in the Western world. The Lake of Cliapala. which receives and dis- charges the Lcmia River, is the largest lake in Mexico; many fine country houses have been built on its shores. Mexico has no really large lakes, though some of the sheets of water, as Cuitzeo and I'atzcuaro. in the State of Michoncan. are famous for their beauty. . considerable ])art of the Valley of Mexico is occupied by six very shallow lacustrine basins, four of the lakes salt. They are the relics of much larger lakes which existed when the Spaniards invaded the country. CuMATK. .As a whole, Mexico is a hot eoun- trv. but its climate, if not one of the most salubrious, is among the most delightful in the wrirlil: the normal warm tcmpcralure is modified by great contra -its in elevations and by the posi- tion and trend of the mountain ranges, which in- fluence the force and direction of the winds and the distribution and amount of the rainfall. The climatic differences depending upon the ilifl'ering altitudes are so great that the vegetable products include almost all that grow between the equator and the arctic regions. In some large areas, however, uniformity of climate prevails; thus the great plains of the northern States, hemmed in bv mountains from sea influences, have the extremes of temperature characteristic of the continental climate in the United States. On the other hand, the Isthmus of Tehuantepec is entirel.v included in the wet tropical zone. Three zones of climate are distinctly marked. The tierra caliente, or hot land, lies along the low maritime zone of the Gulf and the Pacific, and includes swampy and sandy coast lands and well-watered plains and slopes leading up to the mountains. The growth of luxuriant tropical vegetation is promoted by a mean annual tem- perature of 77° to 82° v.. the mcrcurv seldom falling below 00°. but often rising to 100°, and in the sultry districts of ^'era Cruz and Aca])ulco to 104°. Some places, as the port of La Paz, are among the hottest in the world. The sea- coasts are unhealthful. fevers prevail, and in some localities vcllow fever and black vomit are endemic. The health conditions ma.v be greatly improved by draining the swamps, as has already been shown at 'era Cruz. Above the Gulf and Pacific hot zones are the tierras templadns, or tem|)erate lands, from .'SOOO to 0000 feet above the sea, embracing the higher terraces and parts of the central plateau. The temperate lands rise to a higher elevation in the southern than in the northern States. The mean temperature is from 62° to 70° F.. and does not vary more than 4° to 5° during the .vear. Thus extremes of heat and cold are unknown; semitropical products, like those of Soullnvestern Euro|)e, are almndant and to some extent, also, products both of the tropical and cold regions. Around the city of Oaxaca wheat and sugar cane mav be seen growing on the same piece of ground. Above the temperate lands arc the tierras frias, or cold lands. 7000 feet or more above sea level, with a mean temperature of from 50° to 03° P. Most of the central jdateau. with its girdle of mountains, is included in this region, but in great depressions of the surface a warmer temperature and tropical products are found. The less ele- vated parts of this region produce cereals and apples, while the higher grounds, some of which extend above the snow line, have a sparse vegetation. The lower cold lands are the most thickly inhabited regions in Mexico. Owing to the difTercnces of temperature and the ed'ect of the mountain ranges upon the dire<'tion of file winds, the rainfall is verv uneipially dis- tributed. During the rainy season, from the middle of May to October, many torrential storms occur in the southern half of the Republic. Lit- tle or no rain falls in the winter or dry season. The cold lands receive only about one-fifth as much rain as the temperate lands except in some of the mountain districts, where the precipitation is hea-A'. The City of Mexico has a mean rain- fall of .'iO inches a year, which is somewhat in excess of the general supply of the plateau to the north of it. though the precipitation on the moun- tain coast lands is two to four times as great. The extreme northern part of the plateau is semi- arid, reproducing the conditions that prevail in
