The third type of surface is the mountain country -- the "temperate zone of the Tropics"; it is the habitat of the Igorot. From the western coastal hill area the mountains rise abruptly in parallel ranges lying in a general north and south direction, and they subside only in the foothills west of the great level bottom land bordering the Rio Grande de Cagayan. The Cordillera Central is as fair and about as varied a mountain country as the tropic sun shines on. It has mountains up which one may climb from tropic forest jungles into open, pine-forested parks, and up again into the dense tropic forest, with its drapery of vines, its varied hanging orchids, and its graceful, lilting fern trees. It has mountains forested to the upper rim on one side with tropic jungle and on the other with sturdy pine trees; at the crest line the children of the Tropics meet and intermingle with those of the temperate zone. There are gigantic, rolling, bare backs whose only covering is the carpet of grass periodically green and brown. There are long, rambling, skeleton ranges with here and there pine forests gradually creeping up the sides to the crests. There are solitary volcanoes, now extinct, standing like things purposely let alone when nature humbled the surrounding earth. There are sculptured lime rocks, cities of them, with gray hovels and mansions and cathedrals. The mountains present one interesting geologic feature. The "hiker" is repeatedly delighted to find his trail passing quite easily from one peak or ascent to another over a natural connecting embankment. On either side of this connecting ridge is the head of a deep, steep-walled canyon; the ridge is only a few hundred feet broad at base, and only half a dozen to twenty feet wide at the top. These ridges invariably have the appearance of being composed of soft earth, and not of rock. They are appreciated by the primitive man, who takes advantage of them as of bridges. The mountains are well watered; the summits of most of the mountains have perpetual springs of pure, cool waters. On the very tops of some there are occasional perpetual water holes ranging from 10 to 100 feet across. These holes have neither surface outlet nor inlet; there are two such within two hours of Bontoc pueblo. They are the favorite wallowing places of the carabao, the so-called "water buffalo,"[6] both the wild and the half-domesticated animals.