Northwest of this point the range breaks down into Chinlee valley, but directly to the north is another uplift, called the Carriso mountains.  It is a single mass, separated from the range proper by a comparatively low area of less than 7,000 feet altitude, while the Carriso itself is over 9,400 feet above the sea.

The western and northwestern parts of the reservation might also be classed as mountainous.  Here there is a great mesa or elevated table-land, cut and gashed by innumerable canyons and gorges, and with a general elevation of 7,500 to 8,000 feet.  Throughout nearly its whole extent it is impassable to wagons.

The valleys to which reference has been made are the Chinlee on the west and the Chaco on the east of the principal mountain range described.  Both run nearly due north, and the former has a fall of about 2,000 feet from the divide, near the southern reservation line, to the northern boundary, a distance of about 85 miles.  Chaco valley heads farther south and discharges into San Juan river within the reservation.  It has less fall than the Chinlee.  Both valleys are shown on the maps as occupied by rivers, but the rivers materialize only after heavy rains; at all other times there is only a dry, sandy channel.  Chaco “river,” which heads in the continental divide, carries more water than the Chelly, which occupies Chinlee valley, and is more often found to contain a little water.  The valleys have a general altitude of 5,000 to 6,000 feet above the sea.

The base of the mountain range has an average breadth of only 12 or 15 miles, and it is a pronounced impediment to east-and-west communication.  It is probably on this account that the Navaho are divided into two principal bands, under different leaders.  Those of one band seldom travel in the territory of the other.  The Navaho of the west, formerly commanded by old Ganamucho (now deceased), have all the advantages in regard to location, and on the whole are a finer body of men than those of the east.

On the west the mountains break down into Chinlee valley by a gradual slope—­near the summit quite steep, then running out into table-lands and long foothills.  This region is perhaps the most desirable on the reservation, and is thickly inhabited.  On the east the mountains descend by almost a single slope to the edge of the approximately flat Chaco valley.  In a few rods the traveler passes from the comparatively fertile mountain region into the flat, extremely arid valley country, and in 50 or 60 miles’ travel after leaving the mountains he will not find wood enough to make his camp fire, nor, unless he moves rapidly, water enough to carry his horses over the intervening distance.

Throughout the whole region great scarcity of water prevails; in the large valleys during most of the year there is none, and it is only in the mountain districts that there is a permanent supply; but there life is almost impossible during the winter.  This condition has had much to do with the migratory habits of the people, or rather with their frequent moving from place to place; for they are not a nomadic people as the term is usually employed.  This is one of the reasons why the Navaho have no fixed habitations.