606 DEPARTMENT OF THE INTERIOR 



2 GEORGE V., A. 1912 



the tops of peaks. In the latter case the surface may appear closely to 

 conform to the highest summits of the crests and to lie above' the structural 

 valleys 



' The Front ranges are distinguished from physiographic districts 

 adjacent to them by the dominant influence of structure on altitude des- 

 cribed in the preceding paragraphs. In strong contrast, the Great Plains 

 exhibit features of erosion entirely independent of structure. Galton 

 range, though as a mass bounded by structural limits, is within itself appar- 

 ently a simple uplifted block. Whatever minor flexures or faults may 

 exist near the 49th parallel they are not sufficiently pronounced to interrupt 

 the unity of the mountain mass. While the general altitude of 7,500 feet 

 is due to uplift, details of heights express effects of earlier or later 

 erosion only. In this respect Galton range is like the Plains and unlike 

 the Front ranges. 



' On the Plains and over Galton range a peneplain was developed. 

 On the soft rocks of the Plains it was planed flat. On the harder rocks 

 of the Galton mass it was probably not so completely smoothed. Observa- 

 tions of 1901 were neither so extensive nor so precise as to distinguish mon- 

 adnocks from features of later carving, but the general relation of height 

 to an old lowland is as distinct as it is on the Schooley plain, in the High- 

 lands of the Hudson, New York. The peneplain on the Great Plains, the 

 Blackfoot plain, is neither incidental nor local. It is the result of a long 

 cycle of erosion, which affected a wide territory, and its representative 

 must occur in the nearby mountains among the oldest features, if not as 

 the oldest, unless it has been obliterated by later activities. A tentative 

 correlation of the Blackfoot plain with the peneplain over Galton range is 

 a reasonable inference from these facts. Nevertheless, in the intervening 

 Front ranges the observer seeks in vain for that general uniformity of 

 altitudes or that breadth of contour which might represent the Blackfoot 

 plain. 



* The peculiarly bold sculpture of the Front ranges is explicable, off- 

 hand, as an effect of great elevation, from which there resulted special 

 conditions of glaciation and erosion. It resembles the sculpture of the 

 Cascade range, Washington, as nearly as is consistent with diversity of 

 rock-types. But unlike the Cascades, whose summits inherit common alti- 

 tudes from a broad peneplain, the Front ranges exhibit no general upper, 

 limit of heights common to many widely distributed peaks. Instead, they 

 present an extreme case of localized deformation, accentuated by intense 

 corrasion. Realizing this, one may still recognize the position of the oldest 

 topographic surface of the province near the summits of the ranges. It 

 is notable that each peak approaches in height those of its neighbours 

 which stand in similar structural positions — that is, along the strike. A 

 surface restored over the peaks, or over their wider shoulders, should repre- 

 sent that from which they are carved, plus or minus the effects of 

 warping and minus the effects of later erosion. Detailed observations of 



