6 KANSAS CITY REVIEW OF SCIENCE. 



Can we conjecture that originally the present lofty valleys enjoyed a climate 

 more fitted for the growth of large forest trees, or are they the last fragment of a 

 growth that, before the present elevation of our mountain range, flourished at 

 lower altitudes in a belter and longer period of summer months. 



To better elucidate this subject, we will give a brief altitudinal catalogue of 

 the tree growth of our Rocky Mountain range in Colorado, from 5,000 feet altitude 

 in the South Platte valley, to the utmost limit of arboreal vegetation at 12,400 

 feet, in Argentine Gulch, near the Argentine Pass, 13,100 feet altitude. 



LAT. 39° 45' N. PRAIRIE DIVISION. 



From 5,000 feet altitude at South Platte river to 5,400 feet, entrance Table 

 Mountain Canon, on Clear Creek : 



Populus nwnilifera. Sweet Cottonwood, 



Negundo aceroides, Box Elder, 



Salix nigra, Black Willow. 



Within two miles of the canon we find about the last sweet cottonwood. Its 

 place is now taken by the bitter cottonwood, or narrow-leafed cottonwood Populus 

 angulata. 



LAT. 39° 45' N. FOOT HILL DIVISION. 



Altitude from 5,400 to 6,000 feet, limit of wild grapevine — Vitis. 



TREES. 



Populus angulata. Bitter Cottonwood, 



Populus Iremuloides, Quaking Asp, 



Negundo aceroides, Box Elder, 



Cellis crassafolia, Hackberry, 



Juniperus conimunis. Red Cedar, 



Abies douglassii, (very few), 

 Pinus aristata, 

 Abies grandis. 



CANON DIVISION. 



Latitude about 39° 44' to 39° 38'. Altitude from 6,000 ft. to 10,000. 

 Pinus Aristata, Abies douglassii, 



■ Abies grandis, Pinus bahamea, 



Populus tremuloides, Populus angulata^ 



Juniperus communis. 



TIMBER LINE DIVISION. 



From 10,000 feet to 12,400 feet. 

 Pinus aristata, 



Pinus Engelmanni, or Flenilis ? 

 Pinus balsamea, begins at 9000 feet altitude. 

 Abies douglassii. 

 Populus tremuloides, scarce. 



