As the reader will have understood, the period of activity with all the geysers is more or less irregular, except in the instance of Old Faithful. We have no knowledge of a simultaneous eruption having ever taken place. Many of these active springs which now exist will, doubtless, sooner or later subside and new ones will form to take their places, a process which has been going on, no one can even guess for how many ages. ------------------------------------------------------------------------ CHAPTER IV. The Great Yellowstone Lake.—Myriads of Birds.—Solitary Beauty of the Lake.—The Flora of the Park.—Devastating Fires.—Wild Animals.—Grand Volcanic Centre.—Mountain Climbing and Wonderful Views.—A Story of Discovery.—Government Exploration of the Reservation.—Governor Washburn’s Expedition.—“For the Benefit of the People at Large Forever.” In the southern section of the Yellowstone Park, near its longitudinal centre, is one of the most beautiful yet lonely lakes imaginable, framed in a margin of sparkling sands, and surrounded by Alpine heights. One stretch of the shore about five miles long is called Diamond Beach; the volcanic material of which it is formed, being entirely obsidian, reflects the sun’s rays like brilliant gems, while the beach is caressed by wavelets scarcely less bright. Surrounded by many wonders, the lake is itself a great surprise, lying in the bosom of rock-ribbed mountains at an elevation of nearly eight thousand feet above the sea. We know of but one other large body of water on the globe at any such height, namely, Lake Titicaca, in South America, famous in Peruvian history. The Yellowstone Lake is always of crystal clearness, and is fed from the eternal snow that piles itself up on the lofty peaks which surround it, and which are sharply outlined in all directions against the blue of the sky. The outlet of the lake is the Yellowstone River, which issues from the northern end, while the Upper Yellowstone runs into it on the opposite side. The lake is twenty-two miles long by fifteen in width, and has an area of a hundred and fifty square miles. Its greatest depth is three hundred feet, and it is overstocked with trout, many of which, unfortunately, are infested by a parasitic worm which renders them unfit for food; but this is not the case with all the fish; a large portion are good and wholesome. Geologists find sufficient evidence to satisfy them that this lake, now narrowed to the dimensions just given, in ancient times covered two thirds of the present Park. Aquatic birds abound upon its broad surface, and build their myriad nests on its green islands. They are of many species, comprising geese, cranes, swans, snipe, mallards, teal, curlew, plover, and ducks of various sorts. Pelicans swim about in long white lines; herons, in their delicate ash-colored plumage, stand idly on the shore, while ermine-feathered gulls fill the air with their loud and tuneless serenade.