The wide tableland or plateau of Anahuac (q.v.), fringed by these mountains, slopes from south to north, being from 5000 to 9000 feet high in the States of Mexico and Puebla and falling to 3000 feet at El Paso, on the United States border. Its surface is covered with long continued outpourings from the volcanoes and the detritus worn away from the mountain slopes, which, according to Heilprin, filled the original depressions, the valleys of to-day having been imposed upon this new surface. The mountains of the plateau, nearly buried by the aceumula tions of past ages, still rear their heads above the general level, and here and there are continuous ridges o• ranges which divide the surface into well-defined basins such as the Valley of Mexico, nearly 8000 feet above the sea and eompletely inclosed by mountains. The rivers of the plateau have cut deep valleys and eafions, sonic of which are 1000 feet below the general level, extending the warmer influence of the coast lands into the plain. These barrancas. as they are called. are watered by small streams and contrast, by the luxuriance of their vegetation, with the dry and often barren plateau above them. The most fa mous of the barrancas extend from the neighho• hood of Guadalajara through the western 11101111 tains to Colima and Tepic. On the whole, the surface of the plate-au is so level that there was little difficulty. even before there were wagon roads. in traveling by carriage between the City of Mexico and Santa Fe.
The dry and sandy peninsula of Lower Cali fornia, the most remote region of the 'tepid'lie, is also traversed by a range of mountains. broken in two places. and culminating iu Mount Santa Catalina, rising 10.000 feet above the sea nut far south of the neck of the peninsula. Owing to its excessively dry climate and scanty population, this peninsula is Mill little known. The huge quadrilateral peninsula of Yucatan is projected beyond the continental coast line toward Cuba, has no niountain ranges, and its mean altitude is scarcely ahove 100 feet.
IlYnamatApIly. The form of the central plateau, hemmed 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. No :Mexi can river is important for its volume or is valuable for commerce excepting to a very lindted extent. All rivers tributary both to the Gulf of Mexieo and the Pacific' arc obstructed by sand bars at their mouth. The longest river is the _Elio Grande. which rises in Colorado and for 750 miles forms the boundary line between the United States and 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 part of its basin comprises 01.000 square miles, the river
receives sea Feely any perennial stream. Its largest affluent in I\ lexico is the Rio Conehos, which is fed for 200 miles north and south by the eastern slope of the Sierra Aladre Occidental. The Salado tributary collies 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. tither tributaries have the same peculiarity, so that they give a brackish taste to the waters of the _Elio Grande itself. The P:imico. the most con siderable river of the south tributary to the Gulf of Mexico, rises north of the Mexican Valley and empties at the port of 'Tampico. The Cnatzacoal cos. or Snake River. drains the alluvial plain and low 111011111.0 in district. forming the northern slope of the Isthmus of Tehuantepee; 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 Balsas (river of the rafts), which, as its name indicates, is navigable to a limited extent. in its lower reaelies, and the Loma or Santiago, which rises a little west of the I'ity of Alexico, and about fifteen miles front Guadalajara is precipitated over the great falls of duanacat lan, one of the finest waterfalls in the \Vestern world.
The Lake of Chapala. which receives and dis charges the Lerma Inver, is the largest lake in Mexico; many fine country houses have been built on its shores. Alexico has no really large lakes, though some of the sheets of water. as Cuitzeo and Patzeuaro. in the State of Michoapan. are famous for their beauty. A eonsiderable part of the Valley of Nlexien is occupied by six shallow hicustrine basins, four of the lakes salt. They are the relics of much larger lakes which existed when the Spaniards invaded the country.
Cuu.vrv. As a whole, Mexico is a coun try, but its pinnate, if not one of the most salubrious, is among the most delightful in the world; the normal warm temperature is modified by great contrasts in elevations and by the posi tion and trend of the mountain ranges, which in fitience the force and direction of the winds and the distribution and amount of the rainfall. The climatic differences depending upon the differing 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 by 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 entirely included in the wet tropical zone.