494 BOTANICAL GAZETTE © [JUNE 
Boulder Park was selected as the site for the University of 
Colorado Mountain Laboratory, the first session being held in the 
summer of 1909. Several papers (11, 12, 19) have been issued 
setting forth the facilities for field study at the Laboratory, but 
also presenting certain botanical features of the neighboring vegeta- 
tion. Other papers dealing exclusively with the plant life of the 
Park and adjacent territory are referred to in this paper. 
Topography and physiographic history 
GENERAL.—The term “‘park”’ as used throughout the Rocky 
Mountain region refers to an open, flat, usually grassy area in the 
mountains. Such areas may be large, including 100 or more square 
miles; or small, containing only a portion of a square mile, and 
often possess a scattered growth of trees. Boulder Park is the 
broadened valley of South Boulder Creek. It is generally level, and 
through it flows the stream which is slowly working its way back 
and forth and producing well defined flood plains. The level 
portion of the park proper is bordered by steep slopes, the crests 
of which are 500-1000 ft. above the valley floor. The slopes have 
been burned over in large part, and exhibit various stages of the 
“burn succession,” the most obvious of which are lodgepole pine 
andaspen. The climatic climax forest of Engelmann spruce- balsam 
fir is found in places. Some typical talus slopes occur. The 
country granitic rock is exposed in rugged outline in places, and 
may be observed in different stages of disintegration and decom- 
position, and in various stages of vegetative development. The 
building of the Moffat Railroad has created deep rock and gravel 
cuts, gravel and rock heaps and slides, often resembling talus and 
natural slides; likewise, the building of wagon roads has made many 
new areas whereupon secondary succession may be observed. The 
general topographic features of the Park may be seen by referring 
to figs. 1-3. 
In Pleistocene times this area and many others in the mountains 
of Colorado were glaciated. The glaciers had their heads above 
timber line and moved down the valleys, leaving evidence of their 
action. The ice which was largely instrumental in shaping and 
modifying the topography of Boulder Park came from two sources, 
