Estes Park, in Colorado, is one of the most attractive as well as the best known of the mountain parks. Although much smaller than Middle or South Park, it is much larger than hundreds of the other beautiful mountain parks. The Estes Park region embraces about one hundred square miles, though only one third of this is open. The approximate altitude of the ragged lowland park is a trifle less than eight thousand feet. This is entirely surrounded by high mountains which uphold a number of rocky, snowy peaks. In 1875 Dr. F. V. Hayden, father of the Yellowstone Park, wrote of this region: "Within the district treated we will scarcely be able to find a region so favorably distinguished as that presented by Estes Park. Not only has nature amply supplied this valley with features of rare beauty and surroundings of admirable grandeur, but it has thus distributed them that the eye of an artist may rest with perfect satisfaction on the complete picture presented." Erosion and glacial action have given this region its form, while fire made the beautiful opening or park within a forest. The majority of parks or meadow gardens which decorate the forests of the Rocky Mountains probably owe their existence to fire. Trees and grass are endlessly contending for the possession of the earth. In this incessant silent struggle a sweeping fire is generally of advantage to the grass. Trees suffer more from fire than does grass. It is probable that repeated fires enable the grass to hold the plains and prairies against the encroachments of the trees. Each forest fire commonly gives the grass possession of a part of the area formerly dominated by the forest. Usually both grass and trees are prompt to seize any fire-cleared area. The grass may be first to come, or some space may be wet or in some other way unfavorable to tree seed but encouraging to grass seed. While forest fires bring many of these parks, others are glacier meadows, lake-basins which time has filled with sediment and sodded with grass. Many are due to the presence of water, either outspreading surface water or an excess of underground water just beneath the surface,--to streams visible or invisible. A few result from boggy places which result from impaired drainage caused by landslips or fallen trees. Thousands were made by beaver dams,--are old beaver ponds that filled with sediment and then grassed over.