No fact is more strongly borne upon the traveller in Andine and Cordillera-formed countries than that latitude forms but an unreliable guide to climate and temperature. Nearness to the Equator, with its accompanying torridity, is often counterbalanced by high elevations above sea-level, with consequent rarefied air and low temperature—a combination which embodies considerable advantages, as well as some drawbacks. These conditions are very marked in Mexico. Entering the country from Vera Cruz, we rise rapidly from sea-level to 7,410 feet at the City of Mexico; entering from the United States, we rise imperceptibly from 4,000 feet to the same elevation. As to its geographical position, the country extends over 18° of latitude, from 32½° north to 14½° north, and it lies between the 86th and 118th meridian west of Greenwich.
Topographically the country offers a very varied surface, the main features of which are the Great Plateau, the extensive, lofty tableland known as the mesa central; and the Pacific and Atlantic slopes, formed by the flanks of the Sierra Madres mountains towards these oceans respectively. At the base of these ranges are the lowlands of the coasts; whilst the eastern extremity of the country is formed by the singular plains of the peninsula of Yucatan.
A large part of the country's area is taken up by this great plateau of Anahuac, as it is sometimes termed. The tableland is bounded both on the east and the west by ranges of mountains, known as the Eastern Sierra Madre and the Western Sierra Madre respectively. These mountains close in towards the south, enclosing the tableland in a tapering form, and the Valley of Mexico which forms its extremity. On the north the mesa central is intersected by the Rio Grande, which forms the boundary of Mexico with the United States; and the plateau continues thence into the territory of that country. The length of this plateau, from north-west to south-east, or, roughly, upon its longitudinal axis, is approximately 800 miles, and its greatest width between the summits of the enclosing mountains about 500 miles. The tableland is, however, intersected by various lesser ranges of hills, and is not by any means a flat, unbroken expanse. Nevertheless, its formation is such that a vehicle might be driven from the City of Mexico for vast distances without having resort to roads. It may be looked upon physically as a great plane, inclined or tipped from south to north, or from the City of Mexico to the United States border. The general elevation above sea-level of the inclined plane at its southern end is 8,000 feet, and that at its northern 4,000 feet—a slope of 4,000 feet in a direction away from the Equator; and a fact which greatly influences its climate. The Mexican plateau is the result of after-formation from the mountain system of the country. The Sierra Madres are the Mexican Andes, part of the chain-formation of those vast Cordilleras which are most developed in South America, on the one hand, and are encountered in the Rocky Mountains of North America on the other. In South America the Andes consist of huge parallel chains with river and lake-basins of profound depth between them. In Mexico the same formation must have existed, but the basins have been filled up by material discharged from volcanoes and from the erosion of the mountains themselves, doubtless caused by the severe and sudden rain-storms and rapid changes of temperature characteristic of these regions. Thus the great plateau may be likened to a number of filled-up troughs, through whose general surface the tops of mountain ranges still protrude in "islands" or groups, whose crests form the intersecting hills of the plateau. Some of the plains of the plateau between these crests are hydrographic entities, with no outlet for their waters, as in the case of the Bolson of Mapimi—a vast rock-wilderness of 50,000 square miles in area, with great swamps and lake bottoms—and the Valley of Mexico. These great depressions, indeed, in a measure bear out the analogy or relationship with the South American Andes, as in the case of the hydrographic entity of Lake Titicaca in Peru and Bolivia, the great inland sea whose waters have no outlet save by evaporation. The enormous depth of alluvial soil found in the bolsones or depressions of the Mexican plateau, formed from rock-decay, or of volcanic material accumulated by the great lakes of recent times which covered them in the central part of the great mesa central, bear striking evidence to the filling-up process of the past. In the neighbourhood of the River Nazas wells have been sunk to great depths in this material without a single stone or rock of any description being encountered. Indeed, on some of the cotton lands of this region I have looked in vain to find even a pebble, so fine is the alluvial soil. The stratified rocks, which are scarce upon the southern part of the plateau, become much more prevalent in the north, and the vast sandy, arid plains, which cover enormous areas of land in Chihuahua and Coahuila extending thence past the valley of the Rio Grande into the great American deserts of Texas and New Mexico, are doubtless formed from the disintegration of the sandstone and chalk horizons of that region.
Leaving for a moment our examination of the great plateau, let us observe the coast. On both sides of the country—the Gulf of Mexico or the Pacific Ocean—we observe that the littoral is composed of sandy lowlands. On the eastern or Gulf side these coastal plains vary in width from a few miles up to a hundred miles; for the Cordillera approaches near to the sea at Vera Cruz, and recedes far from it in Tamaulipas. Upon the Pacific side, however, the coastal plains are more restricted in width, as the Cordillera runs nearer the sea-coast, but leaving a wider strip at the north. Indeed, in the State of Guerrero the Sierras rise almost abruptly from salt water, and the waves bathe the roots of the trees which cover the mountain slopes. The country rises rapidly from both oceans—more rapidly from the Pacific side—and forms a succession of terraces upon the slopes of the Sierra Madres, traversed by profound transversal cañons and culminating in the crests of these mountains which enclose the great plateau on both sides.
| ASCENDING THE MEXICAN CORDILLERA, OR EASTERN SIERRA MADRE: THE RAILWAY IS SEEN IN THE VALLEY FAR BELOW. |
The Sierra Madres, or Mexican Andes, have the general Andine direction of north-north-west. They are divided into two systems—the western and the eastern—whose respective crests in the north are from 400 to 500 miles apart, enclosing the mesa central, and which approach towards the south. The Pacific range has some important ramifications from its main system, but the general Andine structure is maintained. The range is again encountered in the long peninsula of North-Western Mexico—known as Lower California—where it parallels the eastern side of this great tongue of land for more than 700 miles. Indeed, a study of Mexico's orography and the delineation upon the map shows the series of parallel features formed by alternate mountain-folds and intervening basins—the peninsula of Lower California; the Gulf of the same name; the Western Sierra Madre; the intersecting crests of the great plateau; the Eastern Sierra Madre, and the Gulf Coast. Thus these huge "earth-wrinkles" of the Andine system of South America show their characteristics in Mexico, modified, however, by cross-agencies of volcanic nature. The map of Mexico shows strikingly how the country is formed upon its rocky framework, the ribs of these vast folds.
| THE STATE OF VERA CRUZ: THE PEAK OF ORIZABA; PLAZA OF THE CITY OF CORDOVA. |
The passes over these mountain ranges, giving access to the plateau-interior of Mexico from the oceans, vary from 8,500 feet to 10,000 feet, the range upon the Pacific side being generally the higher. But the highest peaks rise much above these altitudes, in some few cases reaching beyond the perpetual snow-line, although ever much lower than the Andes of South America. Three culminating peaks only pass the snow-line in Mexico, although others of the crests and summits are frequently snow-covered. The first of these three peaks is Orizaba, or Citlaltepetl—the "Star Mountain" of the native—the beautiful and symmetrically formed cone whose gleaming snow-cap is seen by the approaching traveller far over the stormy waters of the Gulf as he approaches the shores of Vera Cruz. So Grijalva and Cortes saw it; so the voyager of to-day sees it, as its snowy point seems to hang in mid-sky, its base buried in clouds and its gleaming summit surrounded by the azure of the tropic firmament. The summit of Orizaba is 18,250 feet above the level of the sea—the highest point in Mexico. Next in point of altitude is the famous Popocatepetl—the "Smoking Mountain," so called by the natives for its eruptions in centuries past, for it is no longer active. Some of the adventurous Spaniards of the band of Cortes reached the rim of the crater on its summit, and, indeed, later the Spaniards extracted sulphur therefrom, and various ascents have been made recently. Its last eruption was in 1665. The summit of Popocatepetl is 17,250 feet above sea-level, and it is of characteristic conical form. The third perpetually snow-capped peak is Ixtaccihuatl—the "Sleeping Woman," so named by the natives from the fanciful suggestiveness of a reclining woman—and its summit is 16,960 feet above the sea. The Indian names of these striking monuments of nature serve to show the poetical nomenclature which the natives of the Americas ever gave to topographical features. Especially was this the case among the Aztecs of Mexico and the Incas of Peru. The last-named mountain is not of the characteristic conical form which volcanoes generally have, its outline—beautiful as it is—forming a serrated edge, and it appeared singularly striking from Tacubaya, where I first beheld it. Nevertheless, all these three mountains—the highest points in the country—are of volcanic origin. The majestic and poetic peaks of the "Smoking Mountain" and the "Sleeping Woman" form part of the Sierra Nevada, or Cordillera of Anahuac, in company with Malinche, another of the highest culminating peaks, 14,630 feet above sea-level. This chain is a cross ridge of volcanic and more recent formation than that of the general system of the Mexican Cordilleras, and forms, as it were, a line of volcanic action at right angles to the general Andine trend, associated perhaps with Orizaba on the east and the volcano of Colima (12,990 feet elevation) on the west. This latter mountain is the only active crater in Mexico at the present time. The great Malinche, or Malintzin—possibly named after the fair interpreter of Cortes—is a mountain of striking form, with its brow often snow-covered, upon the borders of the plateau of Tlaxcala, whilst the singular Cofre de Perote, with its box or coffin-like summit (13,400 feet above sea-level), is a prominent landmark of the eastern slope of Mexico's road from Vera Cruz, overhanging the summit of the Sierra Madre at the limit of the lowlands. Other high peaks are the Nevedo de Toluca, often snow-crowned, 14,950 feet; and Tancitaro, 12,660 feet.