Great Basin National Park
The Great Basin is a region of national significance in that it is a world unto itself. Because of the unique cycling of water in this area, it can be considered an immense closed system. In this closed hydrological system, there are many mountain ranges that operate like islands, isolated by oceans of sage. The Great Basin is a vast natural laboratory to study in detail, such topics as: global warming or other planetary changes that may or may not have resulted from human activity; the role of biological diversity in the maintenance of natural areas; and the power of evolutionary change in an organism's response to a constantly changing environment. There is literally no other place like the Great Basin in the United States, and very few places like it in the world.
What is the Great Basin?
The Great Basin can be defined in three different ways: hydrographically, geologically and biologically. The boundaries defined by these various definitions are not identical. The most commonly used definition is the hydrographic one.
Hydrographic Great Basin
The Great Basin is an approximately 200,000-square-mile area that drains internally. Surface water leaves the Great Basin only by evaporation. No creeks, streams, or rivers find an outlet to either the Gulf of Mexico or the Pacific Ocean. All precipitation in the region evaporates, sinks underground or flows into lakes (mostly saline). The boundaries to the east and west are the Wasatch Mountains of Utah and the Sierra Nevada Mountains of eastern California, respectively. The northern boundary is the Snake River Plain of Idaho and Oregon. The south rim is less distinct. In fact, John Fremont, the explorer who named the Great Basin, postulated a nonexistent mountain range to the south.
The Great Basin includes most of Nevada, half of Utah, and sections of Idaho, Wyoming, California and Oregon. The term "Great Basin" may be slightly misleading because the region is actually made up of many small basins. The Great Salt Lake, Walker Lake, Pyramid Lake and the Carson and Humboldt Sinks are a few of the "drains" in the Great Basin.
Basin and Range
The Basin and Range region is recognized by its unusual topography. It is a product of the geologic forces in the area and has nothing to do with drainage. This area is characterized by many, mostly north-south trending, tilted mountain ranges. These are separated by flat valleys, or basins. This geologic region encompasses most of the Great Basin, as well as parts of Arizona, New Mexico, Texas and Mexico.
Great Basin Desert
The Great Basin Desert is defined by plant and animal communities. The climate of the Great Basin is affected by the rain shadow of the Sierra and Cascade Mountains. It is a temperate desert with snowy winters and hot, dry summers. The valleys are dominated by sagebrush and shadscale. The biologic communities on the mountain ranges differ with elevation, and the ranges act as islands isolated by seas of desert vegetation in the lower, drier valleys.
Great Basin National Park
Great Basin National Park is the only national park that lies deep within the Great Basin, making it one of the most remote parks in the lower 48 states and the only park whose interpretive focus is the Great Basin. Great Basin National Park is located in east central Nevada for many reasons. The area offers superb examples of island biogeography, and as a result, the continuing process of evolution can be studied firsthand. The park also possesses pristine air and water. Bristlecone pine trees, the oldest living trees on earth, inhabit the fragile alpine zone of the Snake Mountain Range. Their tree ring data also offers clues about ancient climate changes.
Islands in the Desert?
Great Basin Mountains rise like islands above flat, dry land. This illusion hints at an important biological truth. Certain species, such as marmots, blue grouse, quaking aspen and bristlecone pine, survive in the region only on these tall, cool mountains. These populations are stranded on green islands in the desert, separated from the rest of their kind to the same extent as plants and animals living on islands in the sea. The Snake Range is a relatively large island located fairly close to the Rocky Mountains of central Utah, a "mainland" area for mountain species. Over millennia, more species arrived in the Snake Range than did on islands farther from the mainland, and more species survived here than did on smaller islands with fewer resources. As a result, the Snake Range has more kinds of plants and animals than most other ranges in the Great Basin.
Details mentioned in this article were accurate at the time of publication