In the irrigable districts much timber will be cultivated along the canals and minor waterways. It is probable that in time a sufficient amount will thus be raised to supply the people of the irrigable districts with fuel wherever such fuel is needed, but often such a want will not exist, for in the Rocky Mountain Region there is a great abundance of lignitic coals that may be cheaply mined. All these coals are valuable for domestic purposes, and many superior grades are found. These coals are not uniformly distributed, but generally this source of fuel is ample. PASTURAGE LANDS. The irrigable lands and timber lands constitute but a small fraction of the Arid Region. Between the lowlands on the one hand and the highlands on the other is found a great body of valley, mesa, hill, and low mountain lands. To what extent, and under what conditions can they be utilized? Usually they bear a scanty growth of grasses. These grasses are nutritious and valuable both for summer and winter pasturage. Their value depends upon peculiar climatic conditions; the grasses grow to a great extent in scattered bunches, and mature seeds in larger proportion perhaps than the grasses of the more humid regions. In general the winter aridity is so great that the grasses when touched by the frosts are not washed down by the rains and snows to decay on the moist soil, but stand firmly on the ground all winter long and “cure”, forming a _quasi_ uncut hay. Thus the grass lands are of value both in summer and winter. In a broad way, the greater or lesser abundance of the grasses is dependent on latitude and altitude; the higher the latitude the better are the grasses, and they improve as the altitude increases. In very low altitudes and latitudes the grasses are so scant as to be of no value; here the true deserts are found. These conditions obtain in southern California, southern Nevada, southern Arizona, and southern New Mexico, where broad reaches of land are naked of vegetation, but in ascending to the higher lands the grass steadily improves. Northward the deserts soon disappear, and the grass becomes more and more luxuriant to our northern boundary. In addition to the desert lands mentioned, other large deductions must be made from the area of the pasturage lands. There are many districts in which the “country rock” is composed of incoherent sands and clays; sometimes sediments of ancient Tertiary lakes; elsewhere sediments of more ancient Cretaceous seas. In these districts perennial or intermittent streams have carved deep waterways, and the steep hills are ever washed naked by fierce but infrequent storms, as the incoherent rocks are unable to withstand the beating of the rain. These districts are known as the _mauvaises terres_ or bad lands of the Rocky Mountain Region. In other areas the streams have carved labyrinths of deep gorges and the waters flow at great depths below the general surface. The lands