Anza-Borrego’s Rocky Backbone

May 17, 2017



Photographer: Ray Boren
Summary Author: Ray Boren

The landscapes seem so very different. Yet the ridges of California’s rugged Anza-Borrego Desert State Park, about 90 miles (145 km) east of San Diego, and the glacier-carved Sierra Nevada farther north — a range renowned for scenic wonders like Yosemite and Kings Canyon National Parks — have a common core. Both are batholiths formed by intrusive igneous plutons that rose and cooled deep within the Earth between 80 and 220 million years ago. Due to tectonic collisions on the western fringe of North America, the rock masses eventually surfaced as what we see today as the Golden State’s arcing granite spine.

In the photo above, taken on March 27, 2017, a granite slope, shattered by weathering called exfoliation, rises above the Montezuma Valley Road (San Diego County S22), west of Borrego Springs, California. The scene sparkles with the sunny blossoms of brittlebrush (Encelia farinosa), while taller ocotillos (Fouquieria splendens), with their red tips, reach for the blue sky. After years of extreme drought, comparatively luxuriant winter and spring rains turned Anza-Borrego into a flowery wonderland. Other blooming plants ranged from desert dandelions to colorful cacti.

The Peninsular Ranges batholith of southwestern California surfaced to form Anza-Borrego’s north-south backbone. The state park — California’s largest, encompassing 600,000 acres — also includes Colorado Desert valleys, canyons, badlands, and an occasional oasis featuring fan palms (Washingtonia filifera), the only palm tree native to the Western United States. Anza-Borrego is also home to rare peninsular bighorn sheep, which give the park part of its name. Borrego is a Spanish word for sheep. In a second photo, taken on the same day and route, a ram strolls a ridgeline. Anza honors Juan Bautista de Anza, a Spanish explorer who pioneered an overland emigrant route through these mountains in 1774. 

Photo Details: Top - Camera Model: NIKON D3200; Lens: Tokina AT-X 124 AF PRO DX II (AF 12-24mm f/4); Focal Length: 24mm (35mm equivalent: 36mm); Aperture: ƒ/11.0; Exposure Time: 0.0020 s (1/500); ISO equiv: 280. Bottom - same except: Lens: Sigma 150-500mm F5-6.3 DG OS APO HSM; Focal Length: 500mm (35mm equivalent: 750mm); ISO equiv: 220.