Dramatic — and Dry — Donner Pass

March 23, 2015

Donner715_31jan15

Photographer: Ray Boren
Summary Author: Ray Boren
 
Donner Pass and Donner Summit, near the California-Nevada state line between Sacramento and Reno, represent a classic crossroads in multiple ways: geologic, human and hydrological. Here a towering mountain range showcases the salt-and-pepper granites of the Sierra Nevada Batholith. Formed in deep magma chambers 150 million to 80 million years ago, the granite has been angled skyward by the ancient and ongoing collisions of the Pacific and North American tectonic plates.
 
The pass (elevation 7,056 ft or 2,151 m), known to early Native American tribes, was used by California-bound emigrants in 1844. Two years later, members of the ill-fated Donner Party, following the Truckee River toward what is now known as Donner Lake, were stranded in an autumn blizzard in which the Sierra Nevada — Spanish for snow-covered mountains — tragically magnified the meaning of their name. In the photo above, taken on January 31, 2015, Donner Lake is visible beyond a snow-free granite outcrop.
 
DONStill, the crossing became a major transportation route, hosting the California Trail — a busy passage after the discovery of gold in California in 1848; the Central Pacific portion of the first Transcontinental Railroad; the Lincoln Highway’s northern route, as the automobile age began; U.S. 40; and Interstate 80 (topping a nearby summit at 7,227 ft, or 2,203 m).
 
A winter passage today across the Sierra Nevada spine at Donner Summit via I-80 underlines another role the range plays. The snowy mountains are a vital reservoir, and as of the end of January, the ancient granite rocks and cliffs are far too evident. The California Department of Water Resources reported on January 31 that the state’s already-severe drought is getting worse: “California relies on the snowpack for about 30 percent of its water during normal years, but the statewide snow water equivalent has shrunk from 50 percent of the multi-year average on December 30 [2014] to 25 percent today… If these conditions continue, California's drought surely will be confirmed for a fourth straight year.”

Photo details: Top - Camera Model: NIKON D3200; Lens: AF-S DX VR Zoom-Nikkor 18-55mm f/3.5-5.6G; Focal Length: 30mm (35mm equivalent: 45mm); Aperture: ƒ/10.0; Exposure Time: 0.0040 s (1/250); ISO equiv: 400; Software: iPhoto 9.5.1. Inset - same except: Focal Length: 18mm (35mm equivalent: 27mm); Aperture: ƒ/9.0; Exposure Time: 0.0063 s (1/160).