The Great North- West— The Territories. 415 



north, the width of their base, or of the plateau from which they 

 rise, is much less than at the 42nd parallel. The elevated tracts are 

 of less extent, and the proportion of cultivable surface is far 

 greater. 



" It will be seen that the thermal lines for each season are thrown 

 farther northward on passing Lake Superior to the westward in the 

 charts of this work than in those of the military report prepared by 

 the author. ... A further collection and comparison warrant 

 the position now given to the thermal lines, placing them farther 

 northward than before, and extending them in a course due north- 

 west from Lake Superior to the 58th parallel. For the extreme 

 seasons, winter and summer, this accurate diagonal extension of the 

 thermal lines across the areas of latitude and longitude is very strik- 

 ing. The buffalo winter on the Upper Athabaska at least as safely 

 as in the latitude of St. Paul, Minnesota ; and the spring opens at 

 nearly the same time along the immense line of plains from St. Paul 

 to Mackenzie River. 



" The quantity of rain is not less important than the measure of 

 heat to all purposes of occupation ; and for the plains east of the 

 Rocky Mountains there may reasonably be some doubt as to the 

 sufficiency ; and doubts on this point — whether the desert belt of 

 lower latitude is prolonged to the northern limit of the plains. If 

 the lower deserts are due to the altitude and mass of the mountains 

 simply, it would be natural to infer their existence along the whole 

 line, where the Rocky Mountains run parallel and retain their alti- 

 tude ; but the dry areas are evidently due to other causes primarily, 

 and they are not found above the 47th parallel in fact. It is deci- 

 sive on the general question of the sufficiency of rain, to find the 

 entire surface of the upper plains either well grassed or well 

 wooded ; and recent information on these points almost warrants the 

 assertion that there are no barren tracts of consequence after we 

 pass the bad lands and the Coteau of the Missouri. Many portions 

 of these plains are known to be peculiarly rich in grasses ; and prob- 

 ably the finest tracts lie along the eastern base of the mountains 

 in positions corresponding to the most desert. The higher latitudes 

 certainly differ widely from the plains which stretch from the Platte 



