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Oh, Ranger!
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Nature's Notes "OH, Ranger, Ranger!" The ranger paused in his talk to a group of Sagebrushers gathered at the upper end of Yosemite Valley. "May I ask a question?" "Yes ma'am," said the ranger, with a twinkle. "Ask me a hard one." "Where is the other half of Half Dome?" Everybody laughed but the ranger. "Well, it's a long story," began the Old-Timer. "But I can tell you. It all happened a long time ago and it is just theory, but so far as I can learn it is as near the truth as anybody has been able to come. Nature leaves her notes to account for everything that has happened in the wilderness, but sometimes it is hard to read them. 
"Do you see that other dome up there, the round one, opposite Half Dome? It is known as North Dome, the perfect dome. Half Dome once looked like that, only much larger. The domes are peculiar to this country. They are solid granite, pushed up through the softer rock. They peel off in layers, like enormous onions, because of the alternate action of the heat and cold on the rock. "The other half of Half Dome was scraped away by the glaciers. What happened was this. When the glaciers came in contact with the walls of Yosemite, the rock contracted under the extreme cold. That cracked enormous pieces loose and they were slowly borne away by the glaciers. Half of Half Dome was shaved off the mountain, cracked up, and pushed away by the ice. It is scattered in boulders down the Merced River Canyon." The ranger paused for the next "hard one." It was not long in coming. "How high is Half Dome?" asked a Sagebrusher. "It towers about a mile above where we are sitting," he said. "Do you mean to say that a glacier could carry away half of a mountain a mile high?" "That is the idea, sir. As a matter of fact, it probably took two glaciers to do the work. During the Ice Age, one mass of ice pushed down Tenaya Canyon and became wedged between Half Dome and North Dome. It finally burst through and met head-on with the other glacier slowly moving down the Merced River Canyon. The two of them churned around with billions of tons of weight behind them and finally plucked and scraped at the cliffs until they carved the present walls of Yosemite Valley. "You can find a record of what happened on those walls up there. If you look closely, you will see spots where the cliffs have been polished as smooth as the cornerstone of a First National Bank. Granite does not crack so smooth naturally. The glaciers, scraping away at the sides of the mountain, polished the rock. That is one means used by Nature to leave her notes for men to puzzle out a million years later. Near Tenaya Lake and again near Merced Lake are perfect examples of glacier polish on the cliffs. "Here in Yosemite Valley, the big job of the glaciers was to shape Yosemite Valley. Streams had already carved a deep gorge, but the glaciers made it wider. When they melted, the gorge became a lake. The streams next dumped sediment into the lake and it became a valley. You can see the same process happening over again, on a much smaller scale, at Mirror Lake. There the streams are now filling up the lake with fine silt. Glacier Point, thirty-two hundred feet above the valley, was left suspended by the glaciers when they melted. One of Nature's little quips was to leave a great rock suspended over the cliff, almost half of it projecting over the rim. That is known as Overhanging Rock." All of the national parks abound in strange phenomena of Nature. These marvels were the motive for setting aside the area as a national park. Dudes and Sagebrushers are not satisfied to come and look at beautiful scenery without knowing why it is there, what happened to make it, and if it will always look that way. Some of the answers to their questions are the solutions to the riddles of the universe. 
The story of the national parks, from a natural history point of view, is an interesting one. In the early days many fakes were perpetrated upon the unsuspecting visitor by guides ill-trained to talk of the wonders of Nature. Often the true answer to a question was not known. So the guide told the Dude that half of Half Dome was shaken down in a great earthquake. To give visitors the true answers to their questions, as well as they can be read from Nature's notes, a staff of ranger naturalists is found in each of the parks. The ranger naturalist's business is to study the mountains, the glaciers, the forests, the animals, the streams, and the other offspring of the wilderness. The nature-guide idea was first undertaken a great many years ago. Dr. H. S. Conard, of Grinnell College, Iowa, former head ranger naturalist of Yellowstone, is the third generation of nature teachers who have taken students and friends afield to study the secrets of the hills and forests. The first excursions into the national parks were conducted by men of scientific training, often college professors and teachers. Later, when travel increased, it was difficult to find enough men adequately trained to talk of the parks' wonders authoritatively. Enos A. Mills, of Rocky Mountain Park, and Dr. Harold C. Bryant, of the University of California, who later became assistant director of the National Park service in charge of the Ranger Naturalist forces, and who is Superintendent of the Grand Canyon, were pioneers in the movement to train ranger naturalists. The regular rangers, though not scientifically trained as a rule, have made themselves reliable practical naturalists to cope with the barrage of inquiries which they are sure to meet each summer. Long experience has taught them never to laugh at any question, albeit foolish. "When do the geysers freeze over?" The Yellowstone ranger hears that one often, and in the old days he used to reply, "Oh, we freeze them over when we need them for skating rinks." But anyone who stops to think, knows that the geysers do not freeze over. So the ranger answers all questions seriously. There is something of the explorer in every person. When he has discovered a petrified tree, he wants to know how wood came to turn to stone, how long ago it happened. It makes the visit to the petrified tree doubly interesting to learn that the wood did not turn to stone but that the grain of the tree, decaying, was replaced by silica from the water, that it happened twenty-five thousand years ago, and that no eruption has taken place in that great span of years to destroy the relic of the last of the earth's upheavals.
In most of the parks, the ranger naturalists have prepared exhibits illustrating the phenomena of the major natural wonders. For example, the whole history of the Yosemite region, from its formation by the ancient upheavals of the earth through the eons of the glacial carvings to its present status, including the living conditions of the Indians, the coming of the whites, and the early stagecoach days, is pictured by means of exhibits in the fine, new fireproof museum, the gift of the Laura Spelman Rockefeller Memorial Foundation.
Returning, for the moment, to the ranger naturalist and his party at the upper end of Yosemite Valley, one of the party is saying, "I wish I could see a glacier at work!" "You can do that, ma'am, if you can stay over a few days. Take the trip up to Tuolumne Meadows and join a horseback party up to Lyell Glacier. That is one of our best small living glaciers. It is hardly big enough to tackle a job like carving Yosemite Valley, but it is grinding away at the side of Mount Lyell, the highest peak in the park. You can see the glacier dragging down boulders from the side of the mountain and breaking them up or dumping them into upper Lyell Fork, where the Tuolumne River starts. Lyell Glacier only moves a few feet each summer. If you selected a boulder at the top of the glacier to watch, it would probably take a hundred years or so to get it down to the bottom of the glacier. Glaciers are slow, but they are sure. "Of course, if you want to see some fast-working glaciers, you might stop off in Mount Rainier National Park. The mountain is farther north and is steeper, also the climate is more severe and much more snow falls in winter. Glaciers move faster because there is more ice behind them to make pressure. Some of those glaciers move along fifty or sixty feet a year. Most of the movement is in the summer time when the ice is cracking and grinding more rapidly. The Mount Rainier glaciers are faster workers than the Yosemite glaciers. They carry so much rock and earth that the ice is dark, almost black, in color. However, an industrious glacier has its disadvantages. The Mount Rainier glaciers scoop up many rocks from the mountain side and grind them together as they slide down the slope, making a fine cement-like powder, which when deposited in the streams, gives them a gray, milky color. This is called glacier milk. Sometimes it is called rock flour. It is interesting, but bad for the fishing. Mount Rainier contains some of the greatest glaciers in the world. 
"There are two kinds of mountains, ma'am, those that are pushed up, and those that are piled up. This mountain range on which we are standing, the Sierra Nevada, was pushed up. It is tilted, the eastern edge of the uplift being from twelve to fourteen thousand feet above the sea and from five to eight thousand feet above the territory immediately surrounding it. The western edge is buried beneath the silt of the San Joaquin Valley. Its slope on the western side is so gradual that if a highway could be built from the San Joaquin to the summit of Mount Lyell in a direct line, the grade would be but two per cent. Yet the Sierra Nevada is considered one of the most formidable mountain barriers on the face of the earth. It is that because of the canyons which streams and glaciers have cut in it. On the eastern slope, the tilt is almost perpendicular. It is said that the Sierra Nevada is a single mountain four hundred miles long and eighty miles wide, the biggest mass of granite in the world. John Muir tells of an earthquake in 1872 which raised the Sierra Nevada thirty-two feet. This was a tremendous upheaval, but you can imagine how puny it must have been compared to the original movements which pushed the whole mountain, eighty miles wide and four hundred miles long, out of the earth. "Mount Rainier, on the other hand, is an example of a mountain that was piled up. They say that the whole state of Washington, which Mount Rainier dominates, was a level plain or else it was under the sea. It's hard to tell what was under a mountain originally. A volcano starts blowing lava and rocks and ashes. It keeps piling up and piling up and piling up some more, perhaps for a million years. Finally, Mount Rainier was built up by lava outpourings to a height of almost three miles. Then the volcano quit working. Layer after layer of snow fell on the mountain as it cooled off. It packed into the crater and became ice. The ice expanded and contracted, as the weather changed, cracking off part of the crater. The ice flowed down the mountain side. Yes, ice can flow. It isn't as solid as it looks, and it will flow when there is enough pressure behind it. "Ever since they started flowing down the sides of Mount Rainier, the glaciers have been grinding down that great mountain. They have probably taken two thousand feet off the top of Mount Rainier in the last million years. In another ten million years there probably won't be much to look at on Mount Rainier. That's one problem that worries the rangers. But the only thing that can save the situation is another volcano and the only national park in which we have a steadily working volcano, Mauna Loa, is in the Hawaiian Islands. We have a live volcano in Lassen Volcanic National Park, but it is lazy and works but spasmodically. "While we are on the subject of mountains, I want to call your attention to Crater Lake. Where the lake now stands there was once a great mountain which a volcano was piling higher and higher. Finally it collapsed inside itself. Mount Mazama, it is called, posthumously. Nobody ever saw it, of course, because this all happened a million years ago, more or less. It must have been a whopping big mountain, at least 14,000 feet high, for when the whole peak caved in it left a hole seven miles in diameter and many thousand feet deep. The deep blue color of Crater Lake has never been explained. A curious feature of this beautiful lake is that, though there is no outlet for the water, it is fresh. That is probably because no streams flow into it, the lake being located on a mountain top. Its waters come from rainfall and melting snows that fall into the lake. There is just about enough of this water to counteract the sun's evaporation."
The mountains seem to be connected in some way with everything. Either they supply the water, or the wood, or the coal, or the mineral, or the scenery, or the plants, or the animals. Build a mountain and then tear it down! That seems to be Nature's whimsical way of working. The Rocky Mountains were once the bottom of a shallow sea. The rangers can take the visitor out in the Yellowstone and show him fossil sea fish and shells. On top of the sea shells he will find a sandstone deposit, the remains of deposits of an ancient lake. On top of that he may find a petrified forest. The forest may be covered with volcanic mud or ash. Then more sandstone; then gravel, the deposit of a river. In one part of the park they know of twelve forests, buried one on top of the other, volcanic mud deposits between them. Eons passed while these forests were growing, each above the tallest tops of its predecessors. In Yellowstone are found several of these petrified forest areas. Lava and ashes destroyed the trees, mud covered them up and provided silica, which replaced the wood cells, preserving for all time the grain of the wood. The preservation of the rings of these ancient trees is of the greatest importance in piecing together the story of the earth. For a long time scientists thought that a large, fat ring indicated a moist, warm year, and that a thin ring indicated a year of drought. It is definitely established that these rings do contain the secrets of climatic records in prehistoric years. In the great redwoods of Sequoia and Yosemite parks, some of which have fallen in recent years, naturalists have traced by means of rings the weather records for the past three or four thousand years. Now if they can connect the record of the rings of the sequoias in their ancient youth with that of the petrified big trees in other parks and monuments, it may be possible to trace the weather report back to the time of the Garden of Eden! Nature leaves her notes in unexpected places!
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Oh, Ranger! ©1928, 1929, 1934, 1972, Horace M. Albright and Frank J. Taylor albright-taylor/chap7.htm — 06-Sep-2004 | ||