What Is Anza-Borrego?

South-facing photo showing storm clouds coming from the west and breaking up when the hit the mountains beside the desert

In terms of the deserts of North America, what we call the Anza-Borrego Desert is a section of the Sonoran Desert. Some references use the term Colorado Desert to refer to portions of the Sonoran Desert which are or have been influenced by actions of the Colorado River. In this sense, Anza-Borrego is part of the Colorado Desert.

The term Anza-Borrego Desert Region is applied to the territory encompassing Anza-Borrego Desert State Park and beyond. The region is in San Diego County and parts of Imperial and Riverside counties in California between the eastern slopes of the Peninsular Ranges (east of Highway 79) and the Salton Sea. In the north, it extends eastward across the Santa Rosa Mountains from the town of Anza on Highway 371. In the south, it extends to the border with Mexico.

The picture above provides an idea as to how this desert comes to be. The picture was taken in the north end of the San Felipe Valley facing south, beside the Volcan Mountains which are part of the Peninsular Ranges. On the morning it was taken, a storm was blowing from west to east (right to left). Mountains such as Granite Mountain which is partly hidden by clouds in the lower third of the picture, just to the right of center, stood in the storm's path. When the storm hit the mountains, the clouds were pushed skyward and apart as most of their moisture evaporated. Little or no rain ever reached the desert. This is what is known as a rain shadow. It is a frequent occurence across San Diego and Orange counties inland from the Pacific Ocean.

Some of the things that people discover when they visit Anza-Borrego are these:

The Plant Kingdom — For most visitors, this means wildflowers. Every Spring (and sometimes even late Winter) people flock to Anza-Borrego to see the displays of wildflower color. Those who visit or live in the desert for all or most of the year know how to find colorful blossoms at other times of the year as well. People get to know the flowers. They study them. Those with an anthropological interest may try to imagine how native people lived here hundreds and thousands of years ago and used these plants for food, shelter and other purposes.
The Animal Kingdom — There is the ever-present coyote. There is the bighorn sheep (borrego in Spanish) for which the area is named. There are regular visitors like Canada geese to the Salton Sea, Swainson's hawks to the Borrego Valley which are preceded by the caterpillars on which they feed. There are a few snakes. There are insects which feed on the flowers. There are birds, some of whom feed on insects and some on rodents, all of whom find water in pools and springs.
The Mineral Kingdom — For rockhounds, the problem with the state park is that you can look at anything you want, but you can't take it home with you. Elsewhere, in Bureau of Land Management territory, these restrictions do not apply as long as you keep what you find for yourself.
Geology — Most visitors probably associate geology with easily visible land formations such as the Borrego Badlands, Split Mountain Gorge, the Carrizo-Vallecito Badlands and various mountains and canyons. Those with a keen eye (and know a fossil when they see one) recognize that Anza-Borrego is a land with a past, a vast area once attached to Mexico and through the ages covered by fresh water and salt water and traversed by streams which supported forests and animals. The area was then, and continues to be, sculpted by earthquakes. Borrego has its faults, several of them.
Anthropology and History — Evidence of prehistoric man has been found in the Yuha Desert. Evidence of Native American life is found throughout all of Anza-Borrego. Many relics of Native American life now are found in private collections or in publicmuseums. The most visible signs of this part of the area's are faint trails, usually in the mountains, and pictographs and petroglyphs which are collectively known as rock art.
Astronomy — Nearby city lights are never a help, of course, but nights in Borrego under clear skies can be wonderful for star-gazing.
Peace and Quiet — There can be plenty of that in Anza-Borrego, too.