PHYSIOGRAPHY 347 



general, however, the summit follows the trend of the fold, and the two 

 may reasonably be considered as being related. 



Valleys and, synclines. — In the Front ranges valleys fall readily into two 

 classes, namely, (1) valleys independent of structure and (2) valleys 

 related to structure. Saint Mary, Swift Current, and Kennedy valleys 

 belong to the first class ; they are effects of streams of water and ice 

 cutting retrogressively headward across the edges of strata which dip 

 away from their direction of fall. Waterton and upper McDonald val- 

 leys belong to the second class, and to them alone need consideration be 

 given here. 



To an observer on central Flattop mountain the synclinal structure of 

 the Front ranges is the obvious fact (figure 1, plate 50, and figure 1, 

 plate 51, in panorama). Scarcely less apparent is the broad synclinal 

 valley of which the summit of Flattop was formerly the floor. For a 

 distance of 12 miles from northwest to southeast the relation is exceed- 

 ingly direct. The summit of Flattop has a general elevation of 6,800 

 feet and the axis of the syncline is parallel to its trend, and northeast- 

 ward and southwestward the mountain slopes and the strata rise to the 

 crests of Lewis and Livingston ranges respectively. The syncline pitches 

 northwestward, but is drained southeastward by McDonald and Mineral 

 creeks, which, united, flow out southwest. This condition may be at- 

 tributed to capture and inversion of a stream which was formerly con- 

 sequent on the pitch. Southeast from and in line with this synclinal 

 valley, shutting it off at that end, is the group of mountains of which 

 Reynolds is a representative. Their relatively great height, 2,000 feet 

 above Flattop, may be due to rise of' resistant limestone and quartzite 

 on the axial pitch. In the other direction Little Kootna creek and 

 Waterton river lie over on the eastern limb of the syncline and crossing 

 the dip on a long slant escape to the plains, while the synclinal axis 

 coincides with peaks that rise to 9,000 feet. The divide, however, is 

 farther west. The unsymmetrical position of Waterton river may be 

 due to conditions preceding folding or to capture following on it ; but 

 its drainage basin is within the syncline, limited by the anticlines of 

 Lewis and Livingston ranges. 



Thus, as might be expected, there are details of stream arrangement 

 which have resulted from adjustment. They have also been affected 

 by glaciation, but the broad fact of a synclinal valley between anti- 

 clinal heights is dominant. 



Distinctive character of Front ranges. — The Front ranges are distin- 

 guished from physiographic districts adjacent to them by the dominant 

 influence of structure on altitude described in the preceding paragraphs. 



