Physical Geography

Except for a tip of the rugged Sierra Nevada mountains in the west and a small section of the lava-underlaid Columbia Plateau in the north, Nevada lies within the Basin and Range region of the United States. Most of the state is within a large section of the Basin and Range known as the Great Basin.

The Great Basin is a broad area without drainage to the sea. It is surrounded by areas of higher elevation and crossed by many elongated and eroded mountain ranges, separated by broad valleys. Most of the ranges are capped by peaks of 8,000 to 11,000 feet (2,400 to 3,400 m) and trend mainly northeast-southwest. Among the many ranges are the Independence Mountains and Santa Rosa Range in the north; the Egan, Schell Creek, and Snake ranges in the east; and the Spring Mountains and Sheep Range in the south. Central Nevada is crossed by the Toiyabe, Toquima, Monitor, Pancake, and other ranges.

The state's highest point is Boundary Peak, reaching 13,143 feet (4,006 m) above sea level. It is in the White Mountains, which extend into Nevada from the Sierra Nevada range to the west. The lowest point, 470 feet (143 m) above sea level, lies on the banks of the Colorado River in the extreme southeast.

Nevada is largely semiarid or arid, consisting mainly of steppes and barren deserts. Most prominent among the deserts are the Black Rock and Smoke Creek deserts in the northwest. Both occupy permanently dry old lake beds. Salt flats (also called playas, sinks, and alkali flats) occur throughout much of the state. There are also mesas, buttes, and other eroded rock formations.

Few rivers in the Great Basin flow throughout the year; most are intermittent streams, flowing only after rains. Those that have a continuous flow either empty into marshes and lakes without outlets or disappear gradually into the arid land.

Chief among the Great Basin's rivers is the southwesterly flowing Humboldt River in the north. It ends at Humboldt Sink. From the Sierra Nevadas flow the Walker River (to Walker Lake), the Carson River (through Lahontan Reservoir to Carson Sink), and the Truckee River (to Pyramid Lake). Pyramid Lake, a remnant of a prehistoric body of water, is the largest lake entirely within the state. High in the Sierras on the Nevada-California state line is Lake Tahoe, one of the most scenic lakes in the United States.

The Colorado River forms the Nevada-Arizona boundary in the southeast. Impounding its water for hydroelectric power, irrigation, recreation, and other uses are Hoover and Davis dams. Hoover Dam's reservoir is Lake Mead; Davis Dam's, Lake Mohave.

Nevada has a middle-latitude steppe and desert climate, except in the extreme south around Las Vegas, where an almost subtropical desert climate prevails. Weather throughout the state is characterized by little precipitation except in the high mountains, wide ranges in temperature, much bright sunshine, and extreme dryness and clarity of air.

The limited rainfall is due mainly to Nevada's position on the leeward side of the Sierra Nevadas, depriving the state of the moisture brought by westerly winds from the Pacific Ocean. Most of Nevada receives less than 10 inches (250 mm) annually; some areas, less than 5 inches (125 mm). Only a few mountain localities receive more than 16 inches (410 mm) annually, partly in the form of heavy snows.

Temperatures vary greatly, mainly because of differences in latitude and elevation. Summers are hot and increase in length and severity from north to south. Average July temperatures range from about 70° to 90° F. (21° to 32° C.). There are extremely high daytime temperatures during summer —often reaching 90° F. (32° C.) to well over 100° F. (38° C.). Nights are normally considerably cooler, by as much as 50° F. (28° C.).

Winters are long and cold in the northeast, short and mild in the extreme south. January averages range from about 25° to 45° F. (-4° to 7° C.). As in summer there are great differences between highs and lows.

Because of its dry climate, Nevada supports mainly scrub vegetation such as sagebrush. In the driest and hottest parts of the extreme south, creosote bushes, cacti, and yuccas are found. Forested areas cover roughly one percent of the land, and are mainly in the mountains. Pine forests predominate. The state's forests are generally not of commercial quality.