THE KANGE. 31 



defoliated by the sheep. It was difficult to find a twig of the former 

 large enough to make a good herbarium specimen. Really the only 

 shrubs not eaten here appear to be mahogany ( Oercocarpus ledifolius) 

 and snowbush (Ceanothus velutinus). Willows are always trimmed 

 up as far as the sheep can reach, and the poplar (Popuhis tremuloides) 

 is not only browsed, but the young trees are often completely girdled. 

 There are two other plants which might be classed with those not eaten 

 by sheep, namely, the sages {Artemisia tridentata) and A. arbuscula, 

 to which should be added the long-leaved sage {A. cana), which is 

 abundant in some localities in Steins Mountains. Even the wild choke- 

 cherry {Prunus emarginatus) is often browsed. The poplar thickets 

 are trimmed up, however, by both cattle and sheep. While the sheep 

 actually eat leaves, twigs, and bark of the young trees, the cattle tramp 

 through the groves a great deal, especially in fly time. 



Being familiar with the destruction of the surface of the country 

 in the deserts of southern Arizona as a result of the removal of the 

 vegetation and the packing of the surface by the trampling of large 

 herds of cattle, a constant effort was made to ascertain the effect of 

 the same agencies here. The conditions in this region, however, with 

 reference to soil characteristics, character and amount of precipi- 

 tation, and configuration of the surface are very different from those 

 of southern Arizona; and the effect of flood waters are consequently 

 by no means identical in the two localities. A comparison of the rain- 

 fall of the two regions will show that the precipitation at Winnemucca, 

 Nev., is less by about 4 inches per annum than at Tucson, Ariz. 

 This, coupled with the fact that the summer showers are much less 

 frequent as well as less violent in the former than the latter place, 

 would lead one naturally to infer that the waters would be much less 

 destructive. The real mollifying influence, however, is not to be 

 found in either the character or the quantity of the precipitation, but 

 in the soil of the mesa, where the destructive action is the most pro- 

 nounced. It is the impervious soil that always washes badly. The 

 surface of the mesa in northern Nevada and southeastern Oregon, as 

 far as observed, never bakes nor otherwise becomes hard and imper- 

 vious to water, as do those lying over the caliche hardpans of southern 

 Arizona. Here the hard impervious soils are found on the bottoms 

 in the basin-like depressions and sinks and along poorly drained river 

 banks. It will be readily seen that the effect of erosion would be to 

 build up and level rather than to cut gorges. It is not meant that 

 there are not notable incidents of recent erosive action here, but an 

 attempt is made to show that the conditions are not as favorable for it 

 and that it is insignificant compared with the same phenomenon on the 

 southern deserts. 



Fire has a direct influence upon the condition of the feed. Burning 

 is as destructive to the grass of the range as to the trees of the forest. 

 Indeed, it had sometimes been thought in more extended observations 



