20 SURVEYS OF FOREST RESERVES. 



tion for defining the mineral areas and the areas that are suitable for 

 agricultural purposes. 



The boundaries of this reserve are defined in part by the lines of the 

 public-land system, none of which have been surveyed. For the pur- 

 pose of locating these boundaries, and also for establishing a basi,s 

 from which other township and section lines could be jtrojected, a spe- 

 cial party was organized. The Montana base line was extended west- 

 ward for a distance of 12 miles, and from this were projected northward 

 and southward lines aggregating about 50 miles. This work was prose- 

 cuted with the greatest difficulty, owing to the rugged and precipitous 

 nature of the territory traversed. The line crossed, at right angles, the 

 spurs making down from the summit of the Bitterroot Eange, which are 

 3,000 or 4,000 feet above the beds of the intervening streams. 



In addition, numerous level lines were run throughout the Bitterroot 

 Valley and as far up the tributary drainage as it was practicable to 

 carry lines of sijirit levels, and in other localities careful elevations 

 were obtained by vertical angulation. 



In the prosecution of the surveys in the Bitterroot reserve there 

 were five parties engaged, employing a varying force of about 35 men, 

 and the sum of $12,606 was expended. This expenditure included the 

 purchase of 9 horses and mules, 3 wagons, and other camp material, 

 such as tents, cooking utensils, etc. 



It is believed that the information obtained in this reserve is sufftcient 

 to answer satisfactorily any question that may arise. 



Forest examinations. — The area of this reserve is 6,480 square miles, 

 or 4,147,200 acres, of which 3,456,000 are in Idaho, and 691,200 are in 

 Montana. 



A portion only of this reserve was examined in detail, consisting 

 of the Montana part of the reserve, together with a small area upon 

 Magruder Fork of Clearwater Eiver. 



Topography. — The State line between Montana and Idaho follows the 

 crest of the Bitterroot Eange, a broad and rugged mass of mountains, 

 rising to altitudes of 6,000 feet in the passes, and to 10,000 feet on the 

 highest peaks. The descent on the east is short and abrupt to the val- 

 ley ot Bitterroot River. Upon the west the spurs are long, and the 

 streams flowing westward into the Clearwater flow, in the main, in deep 

 canyons. 



The east boundary of the reserve, as at present established, crosses, 

 during the most of its course, the mountain spurs and gorges just above 

 the Bitterroot Valley, but near the south end of the valley the reserve 

 is extended eastward so as to include the drainage area of the South 

 and West forks of the Bitterroot. Here the stream is divided up into 

 several branches, these being in narrow valleys, separated by spurs of 

 considerable height. 



Upon the west side of the divide in Idaho the country, so far as 

 examined, consists of an alternation of high mountain spurs and deep, 

 narrow gorges. 



Forests. — At great altitudes and upon the sides and summits of the 

 rocky spurs the forests are scanty and poor. It is only in the lower 

 country, especially in the upper valleys of the branches of the Bitter- 

 root, in the canyons of its tributaries farther north, and on the lower 

 slopes of the mountains, that forests of economic value are found. 

 There may, accordingly, be distinguished two zones of forest distribu- 

 tion, depending upon altitude. The lower of these may be distinguished 

 as the yellow-pine zone, the upper as that of the alpine fir. The areas 

 occupied by these two zones constitute, respectively, 26 per cent and 

 74 per cent of the Montana portion of the reserve. 



