Wagon Tracks from the Old West?

September 06, 2022


Glacial striations

Photographer: Brian Sauls  
Summary Author: Brian Sauls  

No, these aren’t wagon tracks from the Old West. They’re glacial striations, or grooves, that were caused by abrasion from rock fragments embedded in the base of an alpine glacier that once flowed in a valley near north-central Colorado’s Green Mountain Reservoir. These striated and polished rocks consist predominantly of migmatite, which is an igneous/metamorphic rock exhibiting alternating bands of light and dark-colored minerals that formed approximately 1.8 billion years ago, during the Precambrian Era. They have the appearance of a marble cake and are well exposed due to the relatively recent glacial erosion. Based on the orientation of the grooves, one can determine the direction that the glacier flowed. Photo taken in the summer of 1981.

Photo details: Nikon FM camera; Vivitar 24mm f/2.0 lens; Kodak slide film; digitized with Kodak slide scanner.


Green Mountain Reservoir Colorado Coordinates: 39.798056, -106.349444

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Glacial Striations on Snake Butte, Montana