The whole elevated interior of the country forms an immense plateau, much of it composed of broad desert plains upon which the unique and thorny cactus forms the prevailing vegetation. This tableland is an extension southward of that of the western United States, its elevation at El Paso, on the border line, being 3,717 feet. Proceeding to the south it gradually increases in elevation, the city of Mexico lying at a height of 7,400 feet, while at Marquez, 76 miles W. by N. of this city, an elevation of 8,300 feet is attained. South of Marquez the mean level falls little below this. As a result, the air is so rarefied that many persons never become acclimated and foreigners in that land find it judicious not to work too strenuously.

From the foot of the slope on the Atlantic side the tropical borderland slopes gently downward toward the coast through a width varying from a few miles to a hundred miles. The western strip of coastal land is more regular in width, ranging from 40 to 70 miles. The total width of the country, from ocean to ocean, on the United States border is not far from 1,500 miles. Going southward the land gradually narrows until at the narrow isthmus of Tehuantepec it is only about 130 miles wide. While dealing with figures it is well to state that the northern border line has a length of 1,833 miles, 1,136 of which are formed by the channel of the Rio Grande. The area is stated as 767,050 square miles. It is well to speak in passing of the two peninsular regions, the narrow and arid one of Lower California, running southward into the Pacific for about 700 miles, and the broad and fertile one of Yucatan, which extends northward from the southern border into the Gulf of Mexico.

The great difference in elevation between the coast and interior sections of Mexico leads, as above stated, to a wide diversity in climate and physical features. There exist three well-marked climatic zones, presenting the great distinction which elsewhere arises from wide diversity in latitude. The regions of coastal belts and of the ascending terraces to the height of about 3,000 feet are known to the natives as Tierras calientes, or hot lands, being those of tropical temperature and luxuriant vegetation. They are also those of the dreaded yellow fever and of other tropical diseases, epidemics from which the plateau region is free. Above this zone and over the general level of the plateau extend the Tierras templadas, or temperate lands, in much of which the climate may be designated as almost that of perpetual spring, while the humid air which prevails below is replaced by an atmosphere of great dryness. The higher regions of the plateau and the mountain ranges which rise from it constitute the Tierras frias, or cold lands, over which a more wintry weather prevails, the temperature decreasing upon the mountain ranges until the higher peaks ascend to the chilly level of perpetual snow.

The tableland, or great interior plateau, while in great part a broad level, is far from being monotonous in this respect. In fact, it is in many parts a region of mountains. These comprise the Sierra Madre, over 10,000 feet high, extending along both borders of the plateau and stretching through the full length of the country. There are also internal ridges, of volcanic origin, which rise far above the general level. As regards its mountains, however, Mexico is specially distinguished for its volcanoes, of which hundreds are scattered over the plateau, others occurring at points on the western low-lands. Several of these are notable for great height and picturesque aspect. Most prominent among them is the lofty rounded peak of Orizaba, towering 18,250 feet above sea level. Near it in elevation are Popocatepetl ("Smoking Mountain"), 17,500 feet, and Ixticcihuatl ("White Woman"), 16,960 feet in height. These three summits are snow-clad throughout the year. There are others varying from 12,000 to 14,000 feet, and some of lower level which have won fame by destructive volcanic activity, though they are now nearly all extinct or quiescent.

The Sierra Madre may be regarded as the extension in Mexico of the vast mountain backbone of North America, stretching southward from the Arctic Ocean and known as the Rocky Mountains in its northward course. Extending southward along the eastern and western sides of the plateau, their summits about 500 miles apart in the north, these Mexican ranges close in towards the south, the land narrowing and tapering, and inclose in the south the far-famed Valley of Mexico, long the seat of Mexican civilization and empire.

It is probable that Mexico originally consisted of lofty elevations, with low-lying river and lake basins between them, as is now the case in the region of the Andes, but in Mexico the intervening region has been filled up by material eroded from the mountains and lava and ash discharged by its numerous volcanoes, until it has gradually risen to a high general level. This material has filled the basins lying between the interior mountain ridges, until these once high peaks are now reduced to groups of lower-sized hills, breaking the broad general level. The total length of the plateau is about 800 miles, and its greatest width, as above stated, 500 miles, while its southern portion is 4,000 feet higher than its northern. Thus it forms a great sloping plain, tipped upward southwardly, a fact which greatly affects the climate of the southern country. This, while lying within the limits of the tropic zone, has climatic conditions resembling those of the temperate zone.

The method of formation of the lofty Mexican plains has produced in them bolsones, or regions of depression, with alluvial soil of great depth and remarkable fineness, it being in some sections absolutely devoid of stones or pebbles. The result is an unsurpassed fertility, though irrigation is needed for profitable agriculture. In the north, however, rock formations become more prevalent, and here are enormous areas of sand-covered desert, hopelessly arid. These continue northward to form the great American deserts of New Mexico, Arizona, and the neighboring states.

The rivers of Mexico are of little use for navigation. South of the Rio Grande, which forms the northern border, they are chiefly impetuous mountain torrents, or flow through rocky gorges in the sierras, some of them 1,000 feet deep. Their only use for navigation is within the limit of the narrow coastal strips. Lakes are somewhat numerous, but usually small, the largest being Lake Chapala, in the State of Jalisco, which is traversed by the Lerma River, or Rio Grande de Santiago. This is a stream of some importance, flowing through a course of 540 miles, and discharging into the Pacific, after forming the great cascade of Juanacatlan, Mexico's chief waterfall. As in the Great Basin of the western United States, the plateau of Mexico has regions without an outlet to the ocean, their waters gathering into lakes. Such is the case with the Valley of Mexico, the waters of which have no escape except through evaporation and at times have swollen to a devastating height.

The general lack of importance of Mexican rivers for purposes of navigation arises from the formation of the country, with its mountain escarpment and slope on either side and the narrow level between the feet of these and the bordering oceans. Greatest among its rivers is the Rio Grande, which, however, is an international stream, rising in the United States, and flowing for 1,500 miles between the two countries. This is joined by two large tributary streams, the American Pecos and the Mexican Conchos. Next in importance is the Lerma, above mentioned, and farther south is the Balsas, or Mescala, 430 miles long. This has its origin in the slope of the hills surrounding the Valley of Mexico, running in a westerly direction and reaching the Pacific at . Zacatula. It is navigable for only a short distance. Farther north on the Pacific side is the Yaqui, 390 miles long, which makes its way through the sierras of the State of Sonora to the Gulf of California.

On the opposite side of the country, the lowland strip bathed by the waters of the Gulf of Mexico, the most important stream after the Rio Grande is the Panuco. This has its source north of the Valley of Mexico, whence it flows in a broad curve, gathering up in its course a number of afliuents rising in the slopes of the Sierra Madre, and finally making its way down the mountain declivity and reaching the Gulf at the port of Tampico. Into an affluent of this stream empty the canal and tunnel which now drain the city of Mexico. Other streams on the Gulf side are the Papaloapam, which reaches the sea near the port of Vera!Cruz, and the Usumacinta and Grijalva, rivers of the peninsula of Yucatan. As will be seen, most of the rivers of Mexico rise in the mountain barriers, descend their slopes in falls or rapids, and cross the tropic lowlands to the bordering oceans. As a result they are, in their present condition, of little value for irrigation. But their rapid descent from highland to lowland must in time to come give them great value for this purpose and also as sources of electric power. Their scenic effect is in many cases very high.

The Nazas, another Mexican river, is of peculiar character, since its flow is entirely inland over the plateau, it having no outlet to the sea. In time of flood its excess waters fall into the lagoon of Parras, and there evaporate. In this respect it is a parallel to the streams of the Great Basin of the western United States. Little of it, however, reaches this lagoon except in times of flood, its waters being almost or entirely exhausted by the irrigation canals along its course, these feeding the prolific cotton plantations of the Laguna region. The land here is extremely rich, its great depth and width of fertile soil arising from its being the bed of an ancient lake. So valuable is the water of the Nazas River that feuds were formerly common between the cotton growers, dams and weirs being at times blown up with dynamite as a result of their quarrels. The trouble was finally checked by a commission appointed by the government, under the control of which an equitable division of the waters was inaugurated. This stream has with some justice been called "the Nile of Mexico."

A characteristic of the Nazas is the fact that its volume of flow varies remarkably at different seasons. Its bed becomes dry during the dry season, while in the wet it is often filled with a raging flood, extending from bank to bank through its 300 feet of width in half an hour's time. Pouring into the Parras lagoon, this great volume of water goes to waste. By damming and restraining the water when in flood the usefulness of the Nazas might be greatly increased. Tiahualilo ("The Devil") is an aboriginal title for this stream, and seems not ill fitting to it when one of its mighty torrents is in flow.

Many of the lakes of Mexico are of the basin type, filling troughs or depressions in the plateau and mountain regions. Most beautiful among them is Lake Chapala, a great sheet of water eighty miles long and widely noted for its striking scenic charm. Into and out of it flows the Lerma River, carrying its excess water to the Pacific, two hundred miles away. Not less picturesque are two smaller lake basins, Cuitzeo and Patzcuaro, in the State of Michoacan. In the Valley of Mexico is a group of lakes interesting from their connection with the history of the country, those of the region in which the Aztec Empire had its center and the remarkable story of the Spanish invasion took place. These have no natural outlet to the sea, though a partly artificial one has of late years been made by the canal draining the capital city.

These lakes are six in number, five of them being of salt water, one (Lake Chalco) of fresh water. Largest and lowest in altitude among them is the famous Lake Tezcoco, on an island of which was built the city of Tenochtitlan, the famous capital of the conquering Aztecs. Four causeways connected this city with the shore, with breaks crossed by bridges in time of peace, these being easily removed in time of war. During the period that has elapsed since the date of the Spanish conquest the waters of this lake have greatly shrunk in volume. The city of Mexico, which replaced the Aztec capital, no longer stands on an island, but is several miles distant from the shores of the lake. This is a result of the draining operations in this region which have carried off the surplus waters and reduced the level of the lake. These are spoken in a later chapter.

Though the most thickly settled half of Mexico lies within the tropic zone, it reaching nearer to the equator than the most southerly point of Europe, yet its temperature is not what might be expected from this fact, much the greater portion of it being at so high an elevation above the sea that its great plateau might justly be called a vast mountain summit. As a result the mean annual temperature of the city of Mexico (61° 34' F.) closely corresponds with that of the southern cities of Italy and Spain. In this city, however, there is a great diurnal range of temperature, due to its elevated situation, the thermometrical markings varying from 89° F. during the day to 35° F. at night. Those who go about lightly clad in daytime are glad to wear winter clothing after nightfall.

The country has its two climatic periods, the rainy season, extending from May or June to October or November, and the dry season, covering the remainder of the year. During the mid-period of the rainy season very heavy floods are apt to fall, filling up the beds of dried-out streams with torrents that sweep all before them. An example of this kind is that of the Nazas River, above mentioned. In many parts of the desert region deep gullies have been worn in the soil, ready channels for the flood when such a cloudburst takes place, but dangerous ground for the incautious traveler who may be riding along the bottom of one of these treacherous depressions at such a time.

The rainfall varies very much in different localities. Thus in Mexico City the annual fall may be no more than 25 inches, while in Monterey, about 500 miles farther north, as much as 130 inches may fall. Snow, while very rare, is occasionally seen in the capital city. It is as rare in the north, the elevation there being less. When it does appear it is amusing to a stranger from the north to see the peons wrap themselves shiveringly in their blankets and muffle their mouths as though they had suddenly been transported from the torrid to the frigid zone.

The total variation in the annual rainfall is from two or three inches in the deserts on the Arizona border to the great fall of 156 inches in the Isthmus of Tehuantepec, a maximum rarely exceeded elsewhere on the globe. This fall, moreover, occurs during six months of the year, rain ceasing to fall during the six months of the dry season alike in the torrid and the temperature regions of the country.

These variations in climatic condition and in rainfall give a great diversity to the products of Mexico, which vary from the utmost luxuriance of tropical growth to the temperate zone products of the plateau and the desert conditions of the arid regions. As one result of the great change in climate within narrow areas we perceive marked examples of power of adaptation in vegetable, forms, the pine, for instance, a native of cool climes, being seen far down the slopes of the bordering hills, while on the contrary the palms of the tropics at times ascend as high as 8,000 feet above sea-level.

One remarkable plant form of the desert regions of Mexico and the southwestern United States is the cactus, a singular family of plants of many species, which flourish abundantly in Mexico, alike on the desert plateau, on the mountain slopes, and in the tropical plains below. Their native locality, however, is the arid region, where their remarkable capacity for absorbing water, which they store up in their succulent stems against the long periods of drought, enables them to serve as cisterns in the desert to the thirsty traveler. As a self-protective device they are covered with sharp spines, but these do not protect them against the wild horses, which break them open with hoof strokes to drink their treasured stores. Much less do they serve as protection against the ingenuity of man.

Most striking among these unique plants is the great organ cactus, the rounded limbs of which stand erect like a series of organ pipes or the branches of a huge candelabra, forming a remarkable feature of the desert landscape. It needs but a few blows with a machete to bring down one of these tree-like growths and open it for the quenching of the desert thirst. While needle-like spines guard the exterior of the cacti, within they are made up of juicy green cells, dilated with the water which they have stored away for future use. The fruit of many species, especially of the prickly pear, is edible and wholesome, while the flowers of other species are of striking beauty.

The great desert tracts, in which the cacti find their congenial home, are devoid of the higher plant life, but the hill slopes of the boundary mountains abound in places with forest growth. As in the United States, however, the axe of the forester has been overbusy among the forest giants, and large areas, once covered thickly with forests, are now bare. They have been freely cut down for fuel, and this denudation has probably had much to do with the decreasing rainfall and changes in climatic conditions.

The fauna of the country includes three species of the cat family, the jaguar, the cougar or puma, and the ocelot. In the lowland forests monkeys are numerous, five species being present. There is here, also, a species of sloth. In all there are more than fifty species of mammals and over forty of reptiles, among the latter being the alligator and the great boa constrictor. In the region of the mountains and on the plateau wolves abound, including the ever-present coyote, the most abundant wild inhabitant of the desert. Bears of several varieties are also present, and the bison and tapir may be named among the fauna.

Smaller mammals include the beaver, armadillo, marten, otter, etc., while game birds embrace the wild turkey, quail and pigeon. There are many others noted for fine plumage or of songful fame, among them being the mocking bird and multitudes of tiny humming birds of splendid colors, fully fifty species of these being present. A plant of great importance in Mexico is the maguey or agave, two species of which are largely and widely cultivated. From these are produced pulque, the favorite mildly intoxicating beverage of the people, and tequila  and mescal, two fiery spirits resembling inferior grades of brandy, and with similar effects upon the human system. A more useful plant, capable of growing in the indurated soil of Yucatan, is the henequen, yielding a valuable fiber for which there is an unceasing demand. The cultivation of this plant has converted Yucatan, once among the poorest states of Mexico, into one of the richest, while many of its producers have grown very wealthy. The fiber is used in the manufacture of carpets, rugs, ropes, twine and bagging, and the demand for it is unfailing.

Coming now to a, consideration of the mountain system and the general geographical conditions of Mexico, this country is peculiar from being closed in on both sides by what may be considered a coastal range of mountains, since the narrow lowlands which separate them on each side from the sea may have been largely a contribution from the erosion of the mountain slopes. In the State of Guerrero the rocks rise abruptly from the ocean, the waves bathing the mountain foot. Erosion appears also to have been a common process in the interior plateau region, which in certain localities presents an enormous depth of alluvial soil, formed by rock wear or of volcanic material collected in former great lakes, which are supposed to have occupied this internal region. The whole interior thus gives evidence of a vast filling up process in the far past. Wells have been sunk to great depths in the vicinity of the river Nazas without encountering a single stone or rock, and in the cotton lands of this region the soil is so fine that not a pebble is to be found.

The tableland is, as above said, crossed byinterior ranges of hills, and is by no means a flat expanse, yet it is in general so level that one might drive to great distances from the capital without need of following the roads. The interior country presents the aspect of a vast plain, tipped up southward, its southern section being several thousand feet higher than its northern. In it are great depressions lying below the general level, and, like the Valley of Mexico, having hydrographic systems of their own. In addition to this well-known valley may be named the vast depression of Mapimi, a rock wilderness covering 50,000 square miles, in which are great swamps and lake bottoms. In the northern section of the plateau the alluvial soil spoken of is replaced by wide sandy plains, the waste of the sandstone cliffs of that region. In consequence of this, and of the scarcity of rainfall, we find here a vast arid region, covering great areas in Chihuahua and Coahuila and extending northward into the desert section of the United States. The coastal strips bordering the Pacific and the Gulf are also sandy in texture, but prolific from their abundant rainfall.

The two mountain ranges mentioned, respectively the Eastern and Western Sierra Madres, extend southward from the United States border in a south-southwesterly direction, gradually approaching until they merge together in the far south. A spur from the western range forms the backbone of the long, narrow peninsula of Lower California.

The passes over these ranges vary in height from 8,500 to 10,000 feet, those on the Pacific side being generally the higher. Thus a mountain climb of considerable altitude needs to be made from either coastal region to gain the interior plateau. The peaks of the range rise in places far above the altitudes given, some of them extending above the line of perpetual snow. These include the lofty summit of Orizaba, the highest in the country, its elevation above sea level being 18,250 feet. Next in height is Popocatepetl, the "Smoking Mountain," and the third snow-clad peak is that of Ixtaccihuatl, the "Sleeping Woman." The elevation of these is given on page 19.

These three lofty peaks are of volcanic origin, Popocatepetl receiving its name from its former eruptions and the smoke emissions from its summit. Its last eruption was in 1665, it having since been inactive. Some mountain climbers in the band of Cortes reached the rim of its crater and extracted sulphur therefrom. The sulphur deposits are very large, and attempts, not very successful, have been recently made to mine them. The summit of Orizaba has also been reached. This, named by the natives Citlaltepetl, or "Star Mountain," presents a symmetrically rounded and shapely peak, its gleaming snow-cap being visible from far off on the waters, of the Gulf by the traveler approaching Vera Cruz. Popocatepetl also presents a rounded sloping cone, but Ixtaccihuatl is of irregular outline, named by the natives from its suggestion of the form, of a reclining woman.

The only active volcano in Mexico is Colima, in the State of Jalisco, westward from Mexico City and about seventy-five miles from the Pacific coast. The activity of this mountain is traditionally very ancient, and it has been active at somewhat frequent intervals since 1611. It consists of twin peaks, only one of which is active. This is 12,728 feet high, the extinct cone being 14,430 feet. The city of Colima is 27 miles distant, and Tuxpan, a railroad station, is 10 miles away. Much nearer is Tonila, an Indian settlement, which has more than once fallen a prey to the volcanic activity.

Among the striking eruptions from Colima's crater was that of February 15, 1818, when a violent outbreak took place, thousands of tons of volcanic ash being thrown out, to the destruction of a wide area of sugar cane plantations. Three months later, when the mountain had become comparatively quiet, a violent earthquake shook the city of Guadalajara, flinging to the ground one of the great spires of the cathedral. For fifty years after that period Colima confined itself to smoking, but in 1872 it broke again into active eruption, and in 1875 its explosions were of extreme violence. Since then Colima has been in eruption on several occasions, a few years apart. When not erupting, an everlasting crest of smoke curls fitfully above its summit, rising in dull spirals into the air by day and at night illuminating the neighboring haciendas with its lurid gleam.

The earthquakes to which this part of Mexico is somewhat subject seem to have no immediate connection with the eruptions of Colima, occurring usually during its period of quietude. Violent ones took place in 1742 and 1806, in the latter a thousand persons being crushed to death in one church alone. In 1877 Chilpancingo, capital of Guerrero, was partially destroyed by an earthquake, and the city of Colima was violently shaken in 1900. In 1903 the mountain was in eruption again, volcanic ash falling on vessels 300 miles at sea. The whole region seems to be one of eruption and earthquake, and though these do not occur simultaneously they may have one general cause of origin.

A singular volcanic eruption occurred in 1759, of which it will be well to speak. It came not from a mountain, but from under a plantation, that of San Pedro de Jorullo, then covered with fields of sugar-cane, cotton and indigo. In June of that year hollow noises underground gave warning of subterranean trouble, and in September there was an outbreak of smoke and flames from under three or four square miles of ground, which lifted and fell like a wave. Out of the vent came large leaping masses of rock and earth, heaping into volcanic form. A crater was developed from which lava flowed and volcanic ash was hurled upward, this continuing for several months. The roofs of houses were covered with ashes and the plantation was ruined, the trees being thrown down and buried under the erupted material. After doing great damage the eruptions ceased during the following year, and Jorullo became but a name and a memory, but the mountain with its crater remains in evidence of this remarkable example of volcanic activity.