Marbles and Sandstone in Snow Canyon
May 01, 2015
Photographer: Ray Boren
Summary Author: Ray Boren
Small, rounded concretions, popularly called Moqui Marbles on Earth and blueberries on Mars, blanket the top of a sandstone dome in southwestern Utah’s spectacular Snow Canyon State Park. Snow Canyon was named for pioneer brothers, not the weather phenomenon. It sits at the convergence of the American West’s Colorado Plateau, Mojave Desert and Great Basin and features a curious meeting of lithified sand dunes and more recent volcanism.
Noting the iron hematite concretions scattered at sites throughout the Colorado Plateau region, such as Snow Canyon, University of Utah geologists hypothesized that similar balls found on Mars by robot rovers may have formed in similar ways. The earthly concretions are believed to have formed some 25 million years ago as iron carried by groundwater percolated through more ancient Navajo sandstone and coalesced as hematite. In this photograph, taken on March 29, 2015, many of the concretions remain embedded in the sandstone in the foreground. Other marbles have eroded out of the rock, only to gather in and line the surface’s dips, steps and depressions.
Photo Details: Top - Camera Model: NIKON D3200; Lens: Tokina AT-X 124 AF PRO DX II (AF 12-24mm f/4); Focal Length: 12mm (35mm equivalent: 18mm); Aperture: ƒ/11.0; Exposure Time: 0.0020 s (1/500); ISO equiv: 360; Software: iPhoto 9.6.1. Bottom - same except: Focal Length: 16mm (35mm equivalent: 24mm); Exposure Time: 0.0025 s (1/400); ISO equiv: 400.