
209 
shown in the extensive acreage of fallen timber. On the other hand, I 
know of no region throughout the Roeky Mountains where the condi- 
tions seem so favorable for a young growth. During the five yearsthat 
I have carefully observed the forests nothing has so impressed me as 
the rapid, healthy development of the young trees which in afew years 
replace the down timber. In most instances the young growth be- 
longs to Pinus Murrayana, and in every case it is the first tree to spring 
up over a burnt district. 
I need not enter here into a lengthy discussion of the influence of 
the forest upon the supply of water. I simply desire to call your at- 
tention to the special advantages of the Yellowstone Park forest for 
maintaining a water supply of a country singularly well situated to 
gather and distribute a large annual precipitation of moisture. This 
uplifted mountain mass measures 90 miles in length by 60 in breadth. 
From the southwest the moisture-laden winds blowing across the Mad- 
ison plateau precipitate immense quantities of snow and rain over the 
cold, wet table-land. Storms gather over the mountains at all times of 
the year. The annual precipitation is excessive as compared with the 
adjacent regions ef the Rocky Mountains. Rains are of common oe- 
currence between May and September, while during eight months of 
the year nearly all precipitation falls as snow, which lies upon the 
ground well into midsummer, and on the northern slopes, at higher 
altitudes, remains throughout the year. Trosts occur nearly every 
week during the summer, and observations in July and August for sev- 
eral seasons, at various stations over the plateau, show that the mini- 
mum thermometer registers below 40° every night. 
The forests exert a powerful influence in sheltering the snow fields, 
marshes, and meadows from the direct rays of the sun and the dry 
moisture-absorbing winds blowing from the west. Strip the plateau and 
mountains of timber, and early freshets would soon lay waste the lower 
country in spring and leave it arid and parched throughout the summer 
and autumn. Not only would streams diminish, but the ioose gravelly 
soil which now everywhere covers the Park would rapidly be washed 
away, laying bare the underlying rocks. The soil, with theaccompanying 
roots and grasses, playing the part ofa sponge, exert a powerful influence 
in maintaining the water supply. They serve to keep the ground cool 
and moist and allow the water to percolate slowly from the surface to in- 
numerable springs below and thence to the reservoirs of the great rivers. 
With a view of determining with some degree of accuracy the volume 
of water flowing from the Park, the largest lakes and streams were care- 
fully gauged. The measurements were made in early September, 1886, 
not only the dryest period of the summer but the dryest season known 
at any time within the previous five years. [Evidence was ample to 
show that Yellowstone Lake had fallen 20 inches below high-water mark 
of early July. Measurements were made of the discharge from the lake 
at a point on the river about one-quarter of a mile below the outlet. 
24738—Bull 2——14 

