: Creation of the Teton Landscape: The Geologic Story of Grand Teton National Park by Love J D John David Reed John C John Calvin - Geology Wyoming Grand Teton National Park

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Geology is the science of the Earth--the study of the forces, processes, and past life that not only shape our land but influence our daily lives and our Nation's welfare. This booklet, prepared by two members of the U.S. Geological Survey, discusses how geologic phenomena are responsible for the magnificent scenery of the Teton region.

Recognition of the complex geologic history of our Earth is vital to the enjoyment and appreciation of beautiful landscapes and other natural wonders, to the planning of our cities and highway systems, to the wise use of our water supplies, to the study of earthquake and landslide areas, to the never-ending search for new mineral deposits, and to the conservation and development of our known natural resources. Who can say, in the long run, which of the many uses of this knowledge is the most compelling reason to seek an understanding of the Earth?

THE STORY BEGINS

This is a range of many moods and colors: stark and austere in morning sun, but gold and purple and black in the softly lengthening shadows of afternoon; somber and foreboding when the peaks wrap themselves in the tattered clouds of an approaching storm, but tranquil and ethereal blue and silver beneath a full moon.

Most visitors, whatever their interests and activities, are probably first attracted to the park by its unsurpassed mountain scenery. The jagged panorama of the Tetons is the backdrop to which they may turn again and again, asking questions, seeking answers. How did the mountains form? How long have they towered into the clouds, washed by rain, riven by frost, swept by wind and snow? What enormous forces brought them forth and raised them skyward? What stories are chronicled in their rocks, what epics chiseled in the craggy visage of this mountain landscape? Why are the Tetons different from other mountains?

First questions, brief answers

These concepts were developed to explain the origin of mountainous areas hundreds or thousands of miles long but they do not answer directly the question of why the Tetons rose and Jackson Hole sank. As is discussed in the chapter on mountains, it is probable that semifluid rock far below the surface of Jackson Hole flowed north into the Yellowstone Volcanic Plateau-Absaroka Range volcanic area, perhaps taking the place of the enormous amount of ash and lava blown out of volcanoes during the last 50 million years. The origin of the line of weakness that marks the Teton fault along the east face of the Teton Range may go back to some unknown inequality in the earth's composition several billion years ago. Why it suddenly became active late in the earth's history is an unanswered question.

The ultimate source of heat and energy that caused the mountains and basins to form probably is disintegration of radioactive materials deep within the earth. The Tetons are a spectacular demonstration that the enormous energy necessary to create mountains is not declining, even though our planet is several billion years old.

An extraordinary story

An astronaut's view

The Tetons are a short, narrow, and high mountain range, distinctive in the midst of the great chain of the Rocky Mountains, the backbone of western North America. Figure 1 shows how the Tetons and their surroundings might appear if you viewed them from a satellite at an altitude of perhaps a hundred miles. The U. S. Geological Survey topographic map of Grand Teton National Park shows the names of many features not indicated on figure 1 or on the geologic map inside the back cover. The Teton Range is a rectangular mountain block about 40 miles long and 10-15 miles wide. It is flanked on the east and west by flat-floored valleys. Jackson Hole is the eastern one and Teton Basin is the western.

The Teton Range is not symmetrical. The highest peaks lie near the eastern edge of the mountain block, rather than along its center, as is true in conventional mountains, and the western slopes are broad and gentle in contrast to the precipitous eastern slopes. The northern end of the range disappears under enormous lava flows that form the Yellowstone Volcanic Plateau. Even from this altitude the outlines of some of these flows can be seen.

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