TOPOGRAPHY 27 



River, and, especially in their southern part, the mountains pre- 

 sent high and rugged ridges and sharp summits, culminating in 

 Trapper Peak, 10,175 feet. From the ridge the slopes descend 

 more gradually to the Clearwater Mountains, which cover an 

 area some 70 miles east and west and 100 north and south. 

 The average elevation of the Clearwaters is about 7000 though 

 occasional summits rise to 8000 feet. The western border falls 

 abruptly to the Columbia Lava Plateau 3000 to 3500 feet. The 

 whole Clearwater series are but the remains of a dissected 

 plateau, now characterized by sharp ridges, jagged granite peaks, 

 innumerable and intricate canyons and chasms, wild and in- 

 accessible. The Clearwater Mountains, however, are important 

 from the standpoint of the flora, and, as we shall later see, 

 contribute an influence to the vegetation beyond their imme- 

 diate environs. 



The Lolo Fork of the Bitter Root River marks the route of 

 the earliest travelers. It also marks the dividing line between 

 the Bitter Root Range and the Coeur d'Alenes. For about 75 

 miles north and northwest of this pass the character of ,the 

 topography assumes a different aspect. No longer a single high 

 barrier, but a broad, relatively low series of summits and ridges 

 about 6000 feet in elevation, and, like the Clearwater, dissected 

 by numerous channels. To the east lie the open valleys of the 

 upper affluents of the Clark's Fork, to the north the lower por- 

 tion of the same river, and to the west the lake country of the 

 Coeur d'Alenes and the Pend d 'Oreille. The Coeur d'Alene 

 Range is not marked by the rugged features of the Bitter Root 

 and the Clearwater, but present rounded elevations and a more 

 hospitable aspect. The less forbidding nature of this range as 

 ■well as its lower altitude are facts which should be noted in 

 passing as having a bearing on the floristic features to be dis- 

 cussed later. 



North of the Clark's Fork the slopes rise abruptly to the 

 summits of the Cabinet Range, which extends to the valley of 

 the Kootenai. The trend of this range is from southeast to 

 northwest, and from the junction of the Flathead and the Clark's 

 Fork to Bonners Ferry is about 100 miles. The Cabinets are 

 higher than the Coeur d'Alenes, some peaks rising to 8000 feet 

 and with a topography diversified, rugged and picturesque (7). 



