From the study of the record kept in recent years of the rate of deposit of limestone on the cone of Old Faithful, it has been discovered that it took the geyser at least forty thousand years to build up its cone. Some of the other geysers, took much longer. Castle Geyser is estimated to be 250,000 years old. Liberty Cap, that queer cone near Mammoth Hot Springs, took ages to build. No one knows how long it has been extinct, yet for centuries nothing has toppled it over. For all the heat and the weird activity below the earth, the surface has been at rest for many, many years.

Yet it is recorded in the diaries of early hunters and trappers of the Rockies that a volcano was seen to spout brimstone and fire in the Yellowstone area as late as 1811. Unfortunately these early woodsmen kept poor records and scientists cannot now identify the peak the pioneers saw erupting. Equally unfortunate is the fact that many of these early mountaineers, finding their stories were considered great lies, made a sporting proposition of it and told whoppers. Jim Bridger told gravely of how his horse walked across a canyon from rim to rim, in mid-air, with out descending a foot. He explained this feat by allowing that the force of gravity had become petrified temporarily! Finding that his hearers were as yet unpetrified, he told of finding "a petrified forest in which there were petrified birds singing petrified music!"

In Yellowstone National Park, because of the variety of the wonders, it has required a widely scattered force of ranger naturalists to answer the questions of the Dudes and the Sagebrushers. Yellowstone Museum, at Mammoth Hot Springs, is the headquarters of the nature-guide service. In it are found mounted examples of some of our bird and animal life, displays of beaver carvings, exhibits of Indian implements, relics of pioneer settlements and explorations and a fine display of color paintings of Yellowstone wild life, the excellent work of Naturalist E. J. Sawyer. Other museums are at Old Faithful, Norris Geyser Basin and near Fishing Bridge, all telling different stories of Yellowstone's wonderful natural history. Gather around the campfire any summer night and listen to the questions that are asked the ranger naturalists. They run the gamut of the creation and the development of the world, and the resourcefulness and fund of information the ranger naturalists show in answering some of the hard ones are amazing.

"Ranger, where is the mountain of glass?" someone will ask.

"You probably refer to the Obsidian Cliff on the road between Mammoth and Norris Geyser Basin," explains the ranger. "It really is a mountain of black glass thrown up from the interior of the earth by ancient volcanic action. This lava cooled so quickly that it did not crystallize. This hard substance, obsidian, was much prized by the Indians for making arrowheads. Jim Bridger used to tell one of his famous whoppers about the Obsidian Cliff. He claimed that when he passed through the valley on which Obsidian Cliff borders, he saw ahead of him a big bull elk. He took careful aim and shot at the animal, which kept on grazing. Bridger crept closer and fired again. Nothing happened. Three, four, five times he aimed very carefully at the elk and shot, each time creeping closer. He then suddenly found himself face to face with Obsidian Cliff. He had been shooting at the elk, he said, right through the mountain of glass and of course his bullets glanced off the mountain and missed the elk!"

Another curious formation that amazes many people is that of the pentagonal columns which hold up the cliffs on both sides of the Yellowstone River near Tower Falls. These columns are lava that cooled and cracked into remarkably symmetrical geometric figures. There are miles of them and were it not for the many other wonders of the park they would be an outstanding wonder in themselves.

"Ranger, how was this Yellowstone region formed?"

"Geologists tell us that Yellowstone was once a part of a great shallow sea. There are evidences of fossil shells and sea animals found in parts of the park. The theory is that ages ago there occurred a mighty upheaval of mountain masses, forming the Rockies. This was followed by a long period of volcanic activity. The Yellowstone region included several volcanoes, which, with their lava outpourings, formed the great plateau of the park. Blankets of lava spread out over the sea, cooled, were covered with forests. Later, becoming active again, the volcanoes again belched forth, repeating the building-up process.

"The great volcanoes spent their energy, finally, and became quiet, but in many places their furnaces have not yet cooled. They are dying out slowly, but it may take thousands of years for them to cool entirely.

"Why do geysers erupt? Well, you have watched a coffee percolator in action. The geyser works much the same way. The water of geysers and hot springs comes originally from rain and melting snow. Flowing down and coming in contact with lava flows which have but partially cooled, it is heated. The geyser's tube is so long and so narrow that as the water is heated at the bottom it cannot rise to the surface in natural hot springs. Hence it collects at the bottom, the very hot water held down by the pressure of other water on top. Steam is formed below while there is still some water at the upper end of the tube. The steam finally forces its way upward through the water in the tube, emptying the tube through a volcanic eruption. After the steam and hot water are out, the geyser is quiet until enough water and steam gather to repeat the process. In the museum a miniature geyser has been built to illustrate this action."

Most Dudes want to know how far down it is to the fire that heats the water for the geysers. Geologists think that the heat is at least a mile below the surface of the earth. In some spots the hot rocks may be even nearer to the surface, so near in fact that vegetation is baked. On the other hand, these hot rocks near the surface may be heated by steam from farther down.

"Where is the grasshopper glacier, Ranger?"

Many people have heard of these curiosities, of which there are several in the Yellowstone region. The best-known "grasshopper glaciers" are in the Beartooth National Forest just outside the northeast corner of Yellowstone. There are countless millions of grasshoppers, imbedded in the ice. They have been there for centuries, frozen solid. When the sun melts the ice, the grasshoppers disintegrate and the pools at the base of the walls of ice are dark brown in color from the grasshopper "tobacco juice." How they came to be in these glaciers in such quantities is but surmised. The supposed explanation is that year after year great clouds of grasshoppers, passing like a scourge of locusts over these mountains, were caught in snowstorms which forced them down. As the snow froze to ice, the grasshoppers were imbedded in it.

Another mystery that the rangers must clear up often for visitors is that of the "red snow" of the park glaciers. This "red snow" is really not snow at all, but a sort of lichen, scarlet in color, which lives in snow. It is found in several of the parks on glaciers and old snow fields.

Curiosities which rank with the grasshopper glaciers are the nests of ladybug colonies found on the highest peaks of the Sierra Nevada. Climb Mount Lyell in Yosemite National Park at the end of summer, and at the topmost peaks, beneath the rocks, far out of reach of food, you will find millions and millions of ladybugs. Often they are so thick in these mountainous hives that they can be scooped up by the handful. Enterprising "bug men" used to make a business of going to high Sierra peaks to gather ladybugs by the gallon. They were sold by the pint or quart at fancy prices to farmers and orchardists who prize the little bugs for their voracious appetites for certain pests which eat plants and the leaves of trees. But what instinct leads them to fly hundreds of miles to the highest mountains on the continent to pass their winters in zero weather, far from food, is still a mystery.

"Ranger, where is timberline?" is an oft-asked question. Timberline is something that changes with the latitude. In the Arctic circle, timberline is not far above sea level. At the Equator it is said to be about three miles high. It varies in a very definite ratio between altitude and latitude. One mile straight up in the air is the equivalent of eight hundred miles north or south from the Equator, m establishing timberline. Of course, exception must be made to the rule to allow for warm or cold currents of the ocean, or other conditions which may change the temperature materially in certain parts of the earth. The angle of a mountain slope is a factor. Timberline is higher on a southern slope which receives the sun's rays than it is on a northern slope which is in the shade.

This can best be illustrated by an unusual condition in Yosemite Valley, where the steep southern wall is constantly in the shade and the north wall is in the sun all winter long. Consequently, the south side of the Valley is the home of flowers and trees which ordinarily grow a hundred miles or more to the north. The north wall is the home of flowers and trees found far to the south of Yosemite's latitude. The equatorial side of the valley is the colder. This unique set-up has given Yosemite Valley a remarkably rich flora and made it the happy hunting ground of the naturalist. To the cold shade of the south wall trees have migrated from the north and from higher altitudes. In the warm sunlight of the north side of the valley, where there is reflected warmth from the cliffs of that side, are found plants which are known to have thrived in regions as far south as Mexico.

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(From the Stanford University Press edition)

People enjoy the climate of the north side of the valley as much as the plants do, and they live there in the reflected sunlight and warmth of the valley wall, but they only have to go a short distance into the shadows of the south wall to find arctic conditions, cold snow, and winter sports.

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In Yellowstone, timberline is five hundred feet higher on the south slope of Mount Washburn than it is on the north slope. In that park timberline ranges from ninety-five hundred to ten thousand feet. The top of Mount Washburn is in the Arctic-Alpine zone, well above timber line. It is here that one finds the gorgeous gardens of flowers growing against snow banks. These little plants thrive for a brief span in the intense sunlight unfiltered by the heavy atmosphere of the lower levels. The sun's rays bring them out in gorgeous carpets, which blanket the higher slopes of Yellowstone, Rocky Mountain, Glacier, and Mount Rainier National parks.

Life zones are groups of plants and animals living together in agreeable climates. Measured in terms of life zones, a trip from the San Joaquin Valley in California through Sequoia National Park to the summit of Mount Whitney is the equivalent of a journey from Mexico to the Arctic Circle at sea level. As many different kinds of plants and animals would be found on this short trip as on vastly longer trips from south to north.

Most of the national parks, because of their variety of altitude, include several life zones. There are five zones in Yellowstone, for example, reaching from the Alpine zone at the top of Mount Washburn and Electric Peak, through the Sub-Alpine Zone, the Hudsonian, the Canadian, and the Transition to the Upper Sonoran zone. These five zones account for the wide range of trees, flowers, birds, and animals in the Yellowstone. Almost equally great is the variety of life zones in many of the other parks, each of which offers a special field of study for the ranger naturalist and his staff before they can answer the questions sure to be put to them by visitors.

"Well, Ranger, how did arctic plants get to Yellowstone from the Arctic circle?"

"That is a question which seems to worry a good many people. Sometimes they ask if the birds bring the seeds when they migrate. It is very doubtful if they do. The generally accepted explanation is that North America once had a much colder climate than it now enjoys. When the great glaciers spread over the continent, during the Ice Age, the plants that originally grew as far north as the Arctic circle were no longer able to thrive there. They were survived only by descendants which lived farther south. When the ice blanket melted and the climate became warmer, the cold-loving plants growing in the south died out or slowly crept north, following the glaciers back to the Arctic circle. Some of these plants, instead of migrating northward, worked up the slopes and, having established themselves comfortably on the mountain tops and finding the climate congenial, stayed there when their comrades followed the ice back to the Arctic circle. Other and more tropical plants came in and surrounded these little belts of arctic plants, isolating them on the mountain tops.

"These migrations of the flowers and trees form the most fascinating study in the world, once you get into it. A good place to see the flowers migrating is on Mount Rainier, where the glaciers are still retreating, a few feet each year. Each inch they give up is eagerly swallowed up by the army of the flowers, marching up the mountain side. It is said that sometime the flowers will swallow up all the mountain side that now belongs to the great ice sheets. Some day, unless there is another ice age, the flowers will capture the mountain."

Of course, present-day Dudes and Sagebrushers will not see the mountain humbled. These migrations of the flowers have taken thousands upon thousands of years. In the course of the migrations many species of flowers have been lost entirely. For that matter many new ones have been formed, too, by the flowers and trees adapting themselves to new conditions and climates.

Almost equally interesting is the distribution of animals through the life zones. The migrations of the animals are easier to understand. They are not attached to the earth. They can move about and find new homes quite easily. Yet they were distributed through their zones in much the same manner, each animal following the climate that suited him best. So it is that we find the mountain sheep and the little cony, or rock rabbit, in the Hudsonian and sub-Alpine zones of all the national parks, isolated from their kind by many miles of warmer climate which they shun and avoid. There are still species of finches and ptarmigan which prefer to raise their young in the rigorous and cold Arctic-Alpine summits of Rocky Mountain and Glacier National parks, close to the glaciers.

"Ranger, why are the colors of these mountain-top flowers so deep and brilliant?"

"Well," answers the ranger, "scientists have never figured that out exactly and we don't know for sure, but it has been suggested that the reason lies in scarcity of insects on the mountain tops. Insects pollinize the flowers and it would seem natural that they would be attracted to the more brilliantly colored ones, hence these species are pollinized and reproduced, while the poor pale and color less plants in time disappear or at least are not so numerous as to be conspicuous."

Many are the marvels of life at the snowline! For instance, in many parks little willow trees grow that are only two inches tall. They grow up in the Arctic region, too, and are the winter food of the reindeer. "Red asparagus," or snow plant, is another weird example of life. It is a parasite plant. True flowering plants take their food or manufacture it from the air and water. They have green stems and leaves, green being chlorophyll, an essential to their lives. In the case of the snow plant, it manufactures its food from dead or decayed vegetable matter, hence it does not resemble other plants. It is scarlet in color and to all but close observers its general appearance is that of an unusually large stalk of asparagus, hence the name sometimes used, "red asparagus." As a general rule, flowering Alpine plants, grasses, and lichens will grow for a thousand feet above the line of the last stunted and gnarled growths of timber. By the trees and flowers he finds about him, the ranger naturalist who knows the life zones of his park can estimate the altitude of any given locality. In the Sierra Nevada, the Old-Timers can tell the altitude very readily by the combinations of trees, the sugar pine refusing to grow below the six-thousand-foot level, the digger pine refusing to advance above the four-thousand-foot level, the juniper, the Jeffry pine, and the tamarack each choosing its own small sphere on the generous mountain sides.

There is no more fascinating pastime for the Dude or the Sagebrusher from the city than to join the nature-guide parties in any of the national parks, and see how Mother Nature's plans are working out before his own eyes, on the mountain side, where each foot of soil is disputed by a silent and persistent army of plants or trees. A week in the parks with a ranger naturalist with whom to talk things over makes a year with books about these same subjects more fascinating than it could ever be otherwise.