Geology of the Great Basin
Publication Year: 1986
Published by: University of Nevada Press
Title Page, Copyright page, Dedication page
Writing a book on the geology of the Great Basin is like guiding a tour through a great art gallery. Some wish to stop and examine every picture and every detail. Others are anxious to view only the great masterpieces. I decided to describe only what I consider to be the great works of art, and so there is much left unsaid. But without knowledge and appreciation, the...
PART I: Rocks, Concepts, and Processes
The dry sand stretches away as far as I can see to the east and the west. The July sun burns a hole in the sky and sears the desert basin. Shimmering heat waves ripple the sand at the horizon and make the reflections of the mountains flicker upside down on the pseudoliquid surface. The sandy mud has shrunk and cracked since the last summer rain and has formed polygonal fractures...
2. The Great Basin
As a child, I would trace the outlines with a finger and follow the borders of the earth’s great features on maps. My fingertip could scale the Himalayas, struggling upward beside Tenzing Norgay and Sir Edmund Hillary; sail the South Pacific with the great Polynesian voyagers; explore the icy recesses of the Arctic, searching for Sir John Franklin and the crew of the Erebus. But...
3. Raw Materials of the Great Basin
I have not always been a geologist. In fact, I had every intention of being a biologist. I have always been fascinated, even as a child, by the variety and adaptations of life around me. Biology is the science of excitement. Life abounds with freshness and the prospects of discovery. I had a high school friend who was destined to be a geologist and is one today. How boring...
4. Understanding the Earth
Understanding the earth seems to be far too big an order for a mere mortal to attempt. The presumption that we might actually be able to comprehend the materials and the functions of the earth smacks of an egotism that only humans could suggest. Faced with the complexity of design in just one mountain range and the seemingly infinite variety of minerals and rocks in...
5. Time, The Relentless Flow
The most significant contribution of geology to human knowledge and understanding of the earth is our concept of time. No single scientific concept has so altered our view of geologic processes or expanded the potential of possibilities than the availability of vast oceans of time. Given sufficient time, virtually anything is possible. Mountain ranges rise and are pulverized...
6. Fossils, The Timekeepers
If the history of the earth were recorded in a book, the pages would correspond to layers of rock. These layers would usually be sedimentary rock. If these geologic pages were followed sequentially, the history of the earth could be deciphered from the beginning to the present. Each rock layer, like the page of a book, is thin but covers a wide area. Rock materials, scattered...
7. The Restless Earth
During the past forty years, a new idea has swept the geologic profession. The concept is as revolutionary and has been as heatedly debated as the dispute over the age of the earth hundreds of years ago. The idea is termed plate tectonics. Behind the fancy name, the story is that the continents are adrift! And not just continents, but ocean basins as well. In fact, continents are only...
8. Shaping of the Land
Thousands of years ago, Chinese sages developed a philosophy based on careful observation of nature. They concluded that everything is in a dynamic balance of opposites. Nothing is absolute or final. Modern scientists agree. The supposed absolutes of science, careful scrutiny and blunt honesty, yield to dynamic equilibriums. For geologists, uplift and erosion are the yin...
PART II: Great Basin History
9. The Prepaleozoic
Astronomers, peering into their telescopes and recording their observations on sensitive plates, discovered a strange phenomenon many years ago. Every remote galaxy and every far-off object in the universe appeared to be retreating into space away from us. Another perplexing observation showed that the farther away an object was from earth, the faster was its velocity away...
10. The Paleozoic
Slowly, ponderously, the former piece of North America moved westerly. This huge cratonic fragment may have drifted across almost one-half of the globe before affixing itself onto the continental margin of Asia. Later fragments were glued onto its outboard margin, embedding the misplaced fragment of America deeply into Siberian exile. Meanwhile, back along the newly...
11. The Mesozoic
Throughout the 4.5 billion–year history of the Great Basin there have been many significant geologic events. None, however, was more consequential than the Cordilleran orogeny. This mountain-building episode radically transformed the western one-third of the continent. Great tectonic move- ments swept in waves across our region from Late Jurassic to the Eocene.
12. The Cenozoic
After uplift comes erosion. Just as we begin to age from the earliest moments of birth, so the Laramide Highlands began to erode. Erosive forces were scouring the rocks from the earliest time of uplift. They soon revealed signs of the abrasiveness of age; the rocks were deeply beveled. Erosion is the opposite of deposition. When rocks are being destroyed,...
PART III: The Great Basin Today
13. Mineral Resources
Wherever you travel in the Great Basin there is evidence of former or pres- ent mining activity. In some areas the land is so pockmarked with holes and scrapings that it has the appearance of having been the home of gigantic gophers. Some of the largest man-made pits on earth have been dug out of the Great Basin rocks in the search for minerals. Much of the human history of...
The Great Basin is a land of contrast. The outline of the driest region in the United States is defined on the basis of the flow of surface water. The longest river of the region, the Humboldt, rises within the confines of the Great Basin, flows 330 miles to the west, and finally dries up before leaving the region. In fact, all the major rivers of the Great Basin—the Humboldt, Carson,...
Spelunkers like to explore caves. Speleologists study them. Most of us are fascinated by dark recesses under the ground. The soluble Paleozoic carbonate rocks of the eastern Great Basin and the rapid changes in the water table through the coming and going of the Ice Age have created many beautiful solution caves in the area. Lava flows are sometimes hollow, and erosion...
16. Selected GB Parks
Wheeler Peak, one of the highest mountains in the Great Basin, is the thirteen-thousand-foot summit of the Snake Range along the border of Nevada and Utah. The National Park straddles the highlands, and high on the eastern flank of Wheeler peak is Lehman Cave. The cave was carved by acidic groundwater following fractures in lightly metamorphosed carbonate rocks.
17. The Future
The geologic history of the Great Basin relates tales of long-ago volcanism and mountain building. Events are described in the millions, hundreds of millions, or even billions of years. Such a tale tends to leave the reader with a false illusion of security. Monumental events have occurred in our backyards, but they were long, long ago. Surely, such catastrophic occurrences as...
Thousands of prospectors, miners, gem collectors, and geologists have, for more than one hundred years, been picking and poking in the ranges and sandy valleys of the Great Basin. They are the ones who have gathered the geological information about the Great Basin. My role was to piece together that material. Specific individuals, however, were responsible for the creation of the...