28 DEPARTMENT OF THE INTERIOR 



2 GEORGE V., A. 1912 



It is thus seen that the Cretaceous zone at the North Kootenay Pass makes 

 a complete structural and topographic break in the Front range of the Rockies. 

 To the north of the zone Dawson's Livingstone range forms a well-defined unit, 

 its summits being composed of the later Paleozoic limestone. To the south 

 of the zone the Front range, also rugged and in strong topographic contrast 

 to the Cretaceous hills, is essentially composed of quartzites, argillites, and 

 magnesian limestones of pre-Cambrian and earliest Paleozoic age. It seems, 

 therefore, inappropriate to extend the Livingstone range any farther south than 

 the North Kootenay Pass. 



Prom that Pass south to McDonald lake in Montana the great range 

 lying between the Flathead and the Great Plains in Canada and between the 

 Flathead and the Lewis range on the American side of the International 

 Boundary, needs a special name. Such a name has not hitherto been suggested. 

 To supply the need the title ' Clarke range ' may be proposed. The name is 

 taken from that of the colleague of Meriwether Lewis who led the famous 

 Lewis and Clarke expedition into the region in 1806. This splendid range is 

 worthy of the able explorer and his memory is worthy of the range. The new 

 designation for these mountains is in simple mnemonic relation to the name 

 of the adjacent Lewis range, a name which is officially recognized by the United 

 States Geological Survey.* (See Figure 1.) 



After a review of the topographic and geologic relations Mr. Willis has 

 expressed his own belief that the proposed change of nomenclature is advisable. 

 In a letter to the writer he states : 



' I took the name of Livingstone range from a Canadian map with- 

 out particularly investigating the topography north of the boundary. It 

 sufficed for my study at the time to know that there was a range in the 

 United States which was in alignment with one called the Livingstone 



range in Canada 



' Your proposition to give a distinct name to the range in the United 

 States is, I think, fully justified, and the one you select is a most happy 

 counterpart to the name Lewis. I should be glad to have you publish the 

 nomenclature as you suggest, namely, giving to the range west of the 

 Lewis range, from McDonald lake northward to the Kootenay Pass, the 

 name of Clarke range.' 



On the Canadian side of the Boundary for a distance of thirty miles the 

 Clarke range is the Front range. Just north of the Boundary line it runs 

 behind, to the westward of, the equally important member of the system, called 

 the ' Lewis range ' by Willis. At the Forty-ninth Parallel the wide valley 

 occupied by Waterton lake and its affluent, Little Kootna creek, forms a 

 definite boundary between the Clarke and Lewis ranges, which, further south, 

 are separated by the head-waters of McDonald creek. According to Willis, 

 the Lewis range extends southeastward almost to latitude 46° 45'. On the 

 north it ends in Sheep mountain, a couple of miles beyond the International 



* See Chief Mountain sheet of the Topographic Atlas, U.S. Geol. Survey, 



