The Great Basin is the largest closed drainage basin in North America. It is noted for both its arid conditions and its topography that varies from the North American low point at Badwater Basin in Death Valley, CA (282 feet below sea level) to the highest point of the contiguous United States, Mount Whitney, CA (14,505 feet above sea level).
The Great Basin’s boundary is defined three different ways – hydrographic (way the water flows), Geologic (way the landscapes are formed) or Biologic (resident plants and animals). Each definition will give you a different boundary, however, the main, unchanged portion of this puzzle will always remain mostly in Nevada, half of Utah and sections of Idaho, Wyoming, Oregon and California.
They Hydrographic Great Basin is a 200,000 square mile area that drains internally. All precipitation in the region evaporates, sinks underground or flows into a lake. The climate is mostly affected by the rain shadow of the Sierra Nevada and Cascade Mountains. Because of this, the Great Basin receives 7-12 inches of precipitation, which makes Nevada the driest state in the country.
Geologically – Nevada is the only state where the earth’s crust is made up of long, narrow, parallel mountain ranges that are separated by deep flat valleys. This makes the Great Basin the most mountainous area in the country with over 400 mountain ranges. Another unique characteristic of the Great Basin is that these mountain ranges also run North – South. Because of these hundreds of unique valleys and basins, Nevada is home to many microclimates. Microclimates contain a different climate than the surrounding areas. This is evident in the flora and fauna, the soil (clay or nutrient rich), and of course, the weather and it’s extreme range in temperatures.
Biologically – the Great Basin presents such radical elevation changes from its valleys to its peaks, the region supports an remarkable diversity of species, from those adapted to the desert to those adapted to mountainous environments. The Great Basin is dominated by sagebrush, however depending on the elevation, one will see a range of vegetation ranging from sage and bitterbrush in the valleys to Jeffrey Pines, Bristlecone Pines and Manzanita in the higher elevations. . There are 11 species of conifer trees, 73 species of mammals, 18 species of reptiles and 238 species of birds, 8 species of fish and over 800 species of plants – talk about a diversity
Climate – The Great Basin can be separated into hot and cold deserts, or high and low deserts. The lower, hot, Mojave Desert receives most of it’s moisture as rain and the higher, cold, Great Basin Desert receives most of it’s moisture as snow. Although both deserts are hot, the rule is the higher in elevation, the cooler in temperature. The relative humidity is low, so it always feels dry, and there are rapid temperature drops at night. In the summer severe afternoon thunderstorms are common depending on where one might be in the Great Basin area.
Due to the dryness of the area, fires and the long fire season, are extreme dangers in the Great Basin. Sagebrush and cheat grass dominate the Great Basin and provide an excellent fire fuel source. With the new population growth that Nevada has witnessed (will double in 10 years), this makes Nevada a very fragile area. Most people moving to Nevada are from nondesert areas and do not understand the fragile ecology of the desert and the value of it’s biological heritage. Many species have already been affected, or severely harmed, by population growth. It is important to educate, and be aware of, new areas and communities to reduce such impacts to the environment, especially one as frail as the Great Basin.