GEOLOGICAL SURVEY OF THE TERRITORIES. 457 



first meridian. Cottonwood, box-elder, red cedar, plum, and willow 

 are persistent to the base of the mountain. 



The extensive pine forest (Plnus ponderosa,) on the " great divide " 

 south of Denver, although stretching seventy to eighty miles east from 

 the mountains, is not taken into view as belonging to the Plains proper. 

 Its existence, however, suggests the use of its seeds in artificial planta- 

 tions in that region. Settlers in the pinery or its borders would do well 

 to protect portions of the forest by inclosure, and if possible against fire, 

 as by suitable care the forest could be made perpetually remunerative 

 and reproductive. 



The fossil wood, imbedded in the cretaceous strata in many parts of 

 the Plains, is left out of consideration, as belonging to a previous, though 

 recent, geological age ; but the single specimens of trees found growing 

 at wide intervals are silent witnesses to the possibility of extended forest 

 growth. These living trees suggest at once, by their location, the feasi- 

 bility of their increase, and the reason of their scarcity. They are usu- 

 ally found near water ; and hence we conclude that in order to grow 

 trees we must break the ground so deeply as to save all the rains for 

 their use. They are always where they are protected from fires ; and 

 hence we conclude that if we can protect our plantations from fires we 

 can grow forests. 



Were it possible to break up the surface to & depth of two feet, from 

 the ninety-seventh meridian to the mountains, and from the thirty-fifth, 

 to the forty-fifth parallel, we should have in a single season a growth of 

 taller herbage over the entire area, less reflection of the sun's heat, more 

 humidity in the atmosphere, more constancy in springs, pools, and 

 streams, more frequent showers, fewer violent storms, and less caprice 

 and fury in the winds. A single year would witness a changed vegeta- 

 tion and a new climate. In three years (fires kept out) there would be 

 young trees in numerous places, and in twenty years there would be fair 

 young forests. 



Nor is this view inconsistent with the conclusion of meteorologists 

 that our prairies and open plains are due to scanty precipitation. This 

 is the cause ; not, however, because the absolute moisture is not enough 

 to sustain the growth, but because it is not enough to protect it against 

 destruction by fires. Throughout the prairies — the " Illinois region" of 

 Professor Cooper's campestrian province — whenever the fires are checked, 

 tree growth begins. Given immunity from fires on the Plains, and to a 

 great extent, they will clothe themselves with shrubs and trees, even 

 without a breaking up of the surface. 



The limited area which it is in our power to turn up by the plow will 

 have the same results in kind to follow a breaking of the entire surface, 

 but less effective than if the operation were universal. Yet a beginning 

 can be made by the railway company and by individuals. In fact, it is 

 already in progress by settlers, a degree and a half west of ninety-sev- 

 enth meridian. A few acres at intervals across the Plains, or only a few 

 clumps of trees growing without irrigation, will be a demonstration 

 more effective than theory. 



In this great work the United States ought to lead, either by forests 

 planted at the cost of the Treasury, or by subsidies to individuals or 

 companies. It is a work worthy of the age, and of the nation. 



The particular trees most suitable for first planting on the Plains, the 

 modes of culture, the proper succession of species, cannot be treated in 

 a paper already so extended as this. The feasibility of forest growth 

 over this great area is, in my estimation, not to be doubted. The details 

 will be wrought out in due time. 



