A desert is generally defined as an area with less than ten inches of annual rainfall, sparse vegetation, most often with high summer temperatures.
The Southwest portion of the United States fits that definition. Although receiving little rainfall, the rainfall is concentrated into the monsoon season which generally lasts from early July until mid-September. During that period, the Southwest is subject to many thunderstorms and raging flash floods. During the flash floods significant erosion can occur carrying much debris down the washes. This is exacerbated by minimal vegetation as root systems usually have properties of holding soil together.
Hundreds of million years ago the entire region was under the ocean. Over millions of years many layers of sediment were deposited on the ocean floor. As the ocean receded and the land rose, the annual monsoons eroded the Southwest into a multitude of landforms which we see today. But the process is ongoing even now. The mountain are still rising and the erosion from the flash floods and winds continue.
But enough of the climate and the geology! To me the Southwest is a landscape photographer's paradise. It is about pattern. It is about texture. It is about tonal values. It is about compositional possibilities around every corner. And it is about color. So why, you are probably thinking, do I photograph only in black and white? Because this is what I do. Enjoy!