Still pressing upwards, the traveller mounts into other climates, favorable to other kinds of cultivation. The yellow maize, or Indian corn, as we usually call it, has continued to follow him up from the lowest level; but he now first sees fields of wheat, and the other European grains brought into the country by the Conquerors. Mingled with them, he views the plantations of the aloe or maguey (_agave Americana_), applied to such various and important uses by the Aztecs. The oaks now acquire a sturdier growth, and the dark forests of pine announce that he has entered the _tierra fria_, or cold region,--the third and last of the great natural terraces into which the country is divided. When he has climbed to the height of between seven and eight thousand feet, the weary traveller sets his foot on the summit of the Cordillera of the Andes,--the colossal range that, after traversing South America and the Isthmus of Darien, spreads out, as it enters Mexico, into that vast sheet of table-land which maintains an elevation of more than six thousand feet, for the distance of nearly two hundred leagues, until it gradually declines in the higher latitudes of the north.[9] Across this mountain rampart a chain of volcanic hills stretches, in a westerly direction, of still more stupendous dimensions, forming, indeed, some of the highest land on the globe. Their peaks, entering the limits of perpetual snow, diffuse a grateful coolness over the elevated plateaus below; for these last, though termed “cold,” enjoy a climate the mean temperature of which is not lower than that of the central parts of Italy.[10] The air is exceedingly dry; the soil, though naturally good, is rarely clothed with the luxuriant vegetation of the lower regions. It frequently, indeed, has a parched and barren aspect, owing partly to the greater evaporation which takes place on these lofty plains, through the diminished pressure of the atmosphere, and partly, no doubt, to the want of trees to shelter the soil from the fierce influence of the summer sun. In the time of the Aztecs, the table-land was thickly covered with larch, oak, cypress, and other forest trees, the extraordinary dimensions of some of which, remaining to the present day, show that the curse of barrenness in later times is chargeable more on man than on nature. Indeed, the early Spaniards made as indiscriminate war on the forest as did our Puritan ancestors, though with much less reason. After once conquering the country, they had no lurking ambush to fear from the submissive, semi-civilized Indian, and were not, like our forefathers, obliged to keep watch and ward for a century. This spoliation of the ground, however, is said to have been pleasing to their imaginations, as it reminded them of the plains of their own Castile,--the table-land of Europe;[11] where the nakedness of the landscape forms the burden of every traveller’s lament who visits that country.