320 



BOTANICAL GAZETTE 



[may 



II. Physiography 



A. Present. — For convenience we may divide the physiographic 

 features of the region into two groups: (i) the flat summit of the 

 divide and slopes similar to it; (2) the glacial canons. 



■ 



The summit of the divide is an elevated plateau, in some portions 



il^gs 



In places it is r . 6 



km 



or 



more wide, in others it narrows to less than o . 4^™. A few low peaks 

 rise from it, often near its edge, so that they have a precipitous face 

 on that side. The surface is covered with a rather thin laver of rock 



i 



^ 



?- 



■* 



- rrfT^ 



i^-- 



:« 



^i- 



Fig 



■ I.— Summit of the continental divide from Stone's Peak; Long's Peak at the 



dry HieadoW mv^fn'rifT tVit. fl.i+ ^,,wf r xT.. j-_-- ■ r 1 



-—'"*- ^1 i^iit- Luiiuneniai aivide trom btone s reak; J 

 left; the dry meadow covering the flat surface of the divide is shown. 



fragments split off by frost and temperature changes, of small size 

 m most places, but much larger on the higher summits. Similar in 

 every way to the summit of the divide are the slopes that descend to 

 the region of timbcrhne where glacial erosion has not formed cHffs. 



The glacial canons head in a series of fine cirques, immediately 

 under the steep cliffs that form the face of the continental di^'ide {fig- 3) ■ 

 They are separated from each other by projecting spurs of varying 

 width, sometimes flat-topped, but oftener mere ridges, so close together 



When 



lally similar to the summit of the divide, and are in fact continuous 



