This great plateau, whose escarpments, viewed as we approach from either side present the appearance of mountains, is in large part sterile, treeless, and without rivers of importance or navigability. But it is crossed by ranges of steely-blue hills and intersected by fertile valleys, where agriculture is carried on under irrigation--an ancient art by means of canals fed from the intermittent streams. Cacti, strange and gaunt, clothe it by nature, but there are large coniferous forests upon the mountain slopes in places. Do we approach the country from the north, by the railway lines from the United States border, we traverse deserts among the most dreadful of the New World, deserts yet with a certain cruel beauty of their own, where once the Apache roamed--cruellest and most horrible of all the world's savage folk. But Nature has disposed along this high plateau, vast, fabulously vast mineral wealth, and from the famous mines of Guanajuato, Zacatecas, Chihuahua, Durango, Potosi, Aguascalientes, Pachuca; and places--some of them noble towns, dowered with royal charters before the _Mayflower_ sailed for New England--silver and gold poured forth to fill the needy coffers of Spain. Later, the English shareholder tried his hands upon the "mother-lode" with varying fortune, and copper, iron and other metals also came like magic from the rocks of this great wilderness. On the eastern and western versants of the country, and in the south, we encounter a different landscape. Here Nature smiles. In places it may be hot and humid, perhaps malarious, with tangled forests. But rich vegetation, gorgeous flora and profuse animal life--bird, insect, reptile--abound. Here are fruitful plains and valleys, vast sugar-cane plantations, luscious fruits of kinds unknown to the world outside--among them the _mamey_, the "fruit of the Aztec kings," with orange and banana groves, coffee gardens, cocoa-trees, yielding the _chocolatl_ of the Aztecs, rubber-trees with elegant foliage, whilst above, the graceful coco-palm rears its stately column and feathery plume high against the azure sky. [Illustration: SCENE ON THE GREAT PLATEAU, MEXICO. Vol. I. To face p. 104.] Here, indeed, is a region where it might have been supposed that man could dwell in peace and plenty, with a minimum of toil and ambition, of care and evil. The climatic zones of Mexico were named by the Spaniards in accordance with the condition of their varying temperatures respectively, as, the _Tierra Caliente_, or hot lands, the _Tierra Templada_, or temperate lands, and the _Tierra Fria_, or cold lands: the first lying upon the coast, the second midway up the slopes, and the last the higher regions, reaching an elevation of 8,000 to 10,000 feet and more above the level of the sea.