As with all the deserts, the Sonoran is defined generally by the circumstance of little rainfall that arrives unpredictably. Dry winds suck up what moisture does fall, humidity is low, and direct, unfiltered sunlight sears the land. Climate—primarily seasonal heating of the earth’s surface and global wind patterns that generate strong shifts in storm tracks—dictates the locations of the deserts. They are held up by the bookends of the Sierra Nevada on the west and the Rocky Mountains and Sierra Madres on the east, and they share a geological heritage and common landforms.

Nearly two-thirds of the Sonoran Desert’s 120,000 square miles lie in the namesake state of Mexico. In the United States it covers southeast California and southern Arizona. Elevations range from sea level to about 3,000 to 4,000 feet.

While the Sanguaro is the best known cactus of the Sonoran Desert, another columnar cactus shares the spotlight. It is the Organ Pipe cactus, which just barely inches over the Mexican border into the United States. This is the plant that led to establishment of the Organ Pipe Cactus National Monument in far southern Arizona. A trip on the 21-mile Ajo Mountain Drive winds along the foothills of the Ajo Range and takes visitors past impressive stands of organ pipe cacti and through the heart of the Sonoran Desert. (American Deserts Handbook)

Note the organ pipe cactus crest in images #9, 17, and 18. The causes unknown to science yet, these deformities a unique experience.