Mountains in a Sea of Sagebrush
We call it the Great Basin, a vast area of sagebrush-covered valleys and narrow mountain ranges. The name comes from a peculiarity of drainage: over most of the area, streams and rivers find no outlet to the sea. Instead, water collects in shallow salt lakes, marshes, and mud flats, where it evaporates in dry desert air. There is not just one basin here but many, all separated by mountain ranges running roughly parallel, north to south. The landscape plays and replays a single magnificent theme of alternating basin and range - broad basins hung between craggy ranges - from the Wasatch Mountains of Utah to the Sierra Nevada of California in seemingly endless geographic rhythm.
At first glance (or even after many miles of driving) you might think of it as a monotonous landscape - nothing out there but sagebrush, a vast sea of pale green shrubs. Appearances are deceptive. As in the ocean, there is much life not immediately apparent. And above the valleys, rising thousands of feet from the sagebrush sea, mountain ranges form a sort of high-elevation archipelago, islands of cooler air and more abundant water. Here we find a rich variety of plants and animals that could not survive in the lower desert.
Great Basin National Park, established in 1986, includes much of the southern Snake Range, a superb example of a desert mountain island. From the sagebrush at its alluvial base to the 13,063-foot summit of Wheeler Peak, the park includes streams, lakes, alpine plants, abundant wildlife, a variety of forest types including groves of ancient bristlecone pines, and numerous limestone caverns, including beautiful Lehman Caves.
On the Edge of the Desert
The Snake Range provides a good example of biogeography, the relationship between living things and the landscape. As elevation increases, the climate changes, creating habitats for different plants and animals. During the last Ice Age, glaciers sprawled across the high peaks. The air was cooler, allowing forests of bristlecone and limber pine to grow on the valley bottom, along the shores of long sinuous lakes. The largest body of water was lake Bonneville, of which the Great Salt Lake is today a shrunken remnant. About 15,000 years go, its waves lapped a beach just 3 miles from the current park boundary.
That changed around 10,000 years ago, when the climate turned warmer. Glaciers melted, lakes dried up, and the desert plants we see today invaded the desiccated valleys. The Snake Range became an island surrounded by desert, a refuge for temperate-climate dwellers. For many organisms with no means of transport, the desert basins present impassable barriers. These species are cut off from others of their kind, isolated, to develop unique adaptions, as surely as though they were on islands in a real ocean.
A Land of Lakes and Forests
Close beneath the summit of Wheeler Park, a bit of the Ice Age exists in the form of a small glacier, the only one of its kind in the Great Basin. A mere token, it calls to mind the powerful glaciers that capped the Snake Range only a few thousand years ago. Evidence of glacial activity is easy to find. Piles of glacial debris - boulders, sand, gravel - form mounds and ridges. Sparkling Teresa and Stella Lakes occupy hollows gouged by ice.
These were alpine glaciers, not the huge continental ice sheets that enveloped the northern part of the continent. Here, ice never reached the valley floor. Instead, it melted at an elevation of about 9,000 feet. You can see this in the shape of the Baker Creek drainage. Above the melting point, glaciers plucked and carried bedrock, widening and smoothing the mountain slopes. Below the melting point, cascading streams cut sharp-sided canyons.
The Underground World
Lehman Caves (a single cavern despite the name) extends a quarter-mile into the limestone and low-grade marble that flanks the base of the Snake Range. Discovered about 1885 by Absalom Lehman, a rancher and miner, this cavern is one of the most richly decorated caves in the country, a small but sparkling gem.
What we see today began millions of years ago. The climate then was much wetter than it is now. Rain water, turned slightly acidic by seeping past surface vegetation and humus, found its way into hairline cracks deep in the native limestone. Trickling downward, the water dissolved the stone, enlarging the cracks, eventually reaching the water table. There it collected in sufficient quantity to create whole rooms. At one time, an underground stream flowed here, leaving behind tell-tale ripple marks.
Eventually the climate turned drier; water drained from the cave, leaving smooth walls and hollow rooms. Then came the second stage of cave development. Small amounts of water still percolated down from the surface. But now, instead of enlarging the cavern, the mineral-rich fluid began filling it once again. Drop by drop, over centuries, seemingly insignificant trickles worked wonders in stone. The result is a rich display of cave formations, or as scientists call them, speleothems. Lehman Caves contains familiar structures such as stalactites, stalagmites, columns, draperies, and flowstone, along with some interesting and delicate rarities.
Lehman Caves is most famous for the rare and mysterious structures called shields. Shields consist of two roughly circular halves, almost like flattened clam shells. How they are formed remains a subject of controversy - another of the pleasant mysteries to be found in the underground world.
Centered on Nevada but extending into neighboring states, the Great Basin stretches from California's Sierra Nevada Range on the west to the Rockies of Utah on the east. The region is one of high, silent valleys, numerous mountain ranges, and few rivers. Great Basin National Park protects the southern Snake Range, near the Utah border east of Ely, Nevada.
"The Parachute" and other features make touring Lehman Caves an unusual experience.
Helectites look like forests of chow mein noodles.
Aragonite grows clusters of snow-white needles.
Cave popcorn, looking like its namesake, adorns many walls.
The General park map handed out at the visitor center is available on the park's map webpage.For information about topographic maps, geologic maps, and geologic data sets, please see the geologic maps page.
A photo album for this park can be found here.For information on other photo collections featuring National Park geology, please see the Image Sources page.
Currently, we do not have a listing for a park-specific geoscience book. The park's geology may be described in regional or state geology texts.
Parks and Plates: The Geology of Our National Parks, Monuments & Seashores.
Lillie, Robert J., 2005.
W.W. Norton and Company.
9" x 10.75", paperback, 550 pages, full color throughout
The spectacular geology in our national parks provides the answers to many questions about the Earth. The answers can be appreciated through plate tectonics, an exciting way to understand the ongoing natural processes that sculpt our landscape. Parks and Plates is a visual and scientific voyage of discovery!
Ordering from your National Park Cooperative Associations' bookstores helps to support programs in the parks. Please visit the bookstore locator for park books and much more.
For information about permits that are required for conducting geologic research activities in National Parks, see the Permits Information page.
The NPS maintains a searchable data base of research needs that have been identified by parks.
A bibliography of geologic references is being prepared for each park through the Geologic Resources Evaluation Program (GRE). Please see the GRE website for more information and contacts.
NPS Geology and Soils PartnersAssociation of American State Geologists
Geological Society of America
Natural Resource Conservation Service - Soils
U.S. Geological Survey
Currently, we do not have a listing for any park-specific geology education programs or activities.
General information about the park's education and intrepretive programs is available on the park's education webpage.For resources and information on teaching geology using National Park examples, see the Students & Teachers pages.