The conditions which nature has established around this remarkable fountain-head are admirably adapted for the creation and maintenance of an unlimited water supply. Over an area of more than 5,000 square miles there prevails an average altitude of perhaps 7,500 feet; sufficient to insure enormous annual snowfalls, but not so great as to prevent their complete melting in summer. But, that they may not melt too rapidly, the whole region is covered with a thick forest growth cutting off the intense rays of the summer sun, and covering the ground with a vegetable mold through which the surface waters filter but slowly. It is a conservative estimate, based upon observations in connection with road work in the Park, that these forests prolong the melting of the snows from four to six weeks. This condition greatly lessens the liability to sudden floods, and maintains a generous supply of water far into the summer. It has been estimated[AW] that from the Park alone, at low water, there flows per second 4,000 cubic feet of water. If the time ever comes when this supply is so far used as to threaten exhaustion, there will be found in the basin of Yellowstone Lake the most perfect facilities in the world for the construction of an artificial reservoir of almost limitless capacity at a comparatively insignificant cost. A dam could be thrown across the gorge at the first rapids in the Yellowstone below the Lake, and without injuring the natural condition of that region, could easily be made to quadruple the present capacity of the Lake. [AW] By Dr. William Hallock, United States Geological Survey. The Park with its contiguous area thus presents magnificent possibilities in the development of the surrounding country--possibilities of which its founders little dreamed, but which they unconsciously foreshadowed when they declared that this region should be forever set apart for the "benefit" as well as for the "enjoyment" of the people. Besides its wealth of trees, the Park produces other interesting flora. Interspersed among the forests and ornamenting the open glades are flowers and shrubs in endless profusion. We quote from the description of one of the early visitors: