Boulder Canyon (Colorado River) Boulder Canyon (Colorado River) Boulder Canyon, originally Devils Gate Canyon, is a canyon on the Colorado River, above Hoover Dam, now flooded by Lake Mead. It lies between Clark County, Nevada and Mohave County, Arizona. It heads at western end of the Virgin River Basin of Lake Mead, at about . Boulder Canyon divides the Black Mountains into the Black Mountains of Arizona, and the Black Mountains of Nevada. Its mouth is now under the eastern end of the Boulder Basin of Lake Mead, between Canyon Point in Nevada and Canyon Ridge in Arizona. Its original mouth is now underneath
Agriculture in the Southwestern United States any other region of the United States, so it is warmer on average. There are two main physiographic regions which Arizona is a part of. North and east Arizona is part of the Colorado Plateau, and the Basin and Range is in southern and western Arizona. The Colorado Plateau is a flat, elevated land of soft sedimentary rock about 5,000 to 9,000 feet above sea level. Rivers cut deep canyons and gorges into the plateau, the largest of which is the Grand Canyon of the Colorado River, which is in the northwest corner of Arizona. There are also scattered mountains