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 canyons and culminating in the crests of these mountains which enclose the great plateau on both sides. [Illustration: 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. [Illustration: THE STATE OF VERA CRUZ: THE PEAK OF ORIZABA; PLAZA OF THE CITY OF CORDOVA.]