The White Cliff of Alta, with Autumn Gold
October 01, 2018
Rising across northern Utah’s Little Cottonwood Canyon from the mountain resort villages of Alta and Snowbird is a marble-esque white-and-gray cliff that's even more striking when the leaves of quaking aspen trees (Populus tremuloides) begin to turn a complementary autumn gold, as illustrated in these photographs, taken on Sept. 12, 2018.
The tilted scarp is Mississippian/Cambrian age limestone, according to the Utah Geological Survey, initially deposited more than 330 million years ago — long before the rise of the Rocky Mountains — as sediment in shallow seas along a continental shelf that stretched across much of western North America. Over time, heat and pressure compacted and hardened the sediments, including coral and other fossil bits, to rock. Such limestones are also exposed in neighboring canyons southeast of Salt Lake City in the Wasatch Range, which was uplifted along the Wasatch Fault between 15 and 20 million years ago.
The varied rock formations of Little Cottonwood Canyon — from intrusive igneous and granitic quartz monzonite and granodiorite to sedimentary shales and limestones — were gouged into a classic canyon U shape by Pleistocene glaciers until as recently as 11,700 years ago, Utah Geological Survey publications note. Little Cottonwood subsequently proved a treasure trove to silver, lead and gold miners in the late 19th and early 20th centuries, when Alta was founded and initially flourished. In the 1930s and afterward, the former mining town was transformed into a ski resort, renowned for its crystalline snow and beautiful setting. Snowbird Ski and Summer Resort opened just west of Alta (and the towering white and gray wall) in the 1970s, appropriately naming one of its upscale facilities The Cliff Lodge.
Photo Details: Top - Camera: NIKON D3200; Exposure Time: 0.0020s (1/500); Aperture: ƒ/11.0; ISO equivalent: 280; Focal Length (35mm): 105. Bottom - same except: ISO equivalent: 400; Focal Length (35mm): 330.