Weathered Cliffs Along the Madison River in Montana

September 07, 2016

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Photographer: Linda Weirather
Summary Author: Linda Weirather

These weathered cliffs along the Madison River between Bozeman and Ennis, Montana, contain some of the oldest rocks in the United States. Dated to about 3.3 billion years, they've been deeply buried and metamorphosed during multiple tectonic collisions. River cobbles and fresh rockfalls reveal their gneiss patterns. This northern end of the Madison Mountain Range and mountains throughout the Wyoming Craton were faulted upward during the compressive forces of the Laramide Orogeny.
 
Today, extensional faulting shapes these mountains as recently as the nearby 1959 Hebgen Lake Earthquake (7.3 magnitude) and the 1983 Borah Peak Earthquake (6.9 magnitude) in Idaho. This part of the canyon has a nearly treeless semi-arid microclimate that boosts afternoon heating for leisurely float trips along this gentle stretch of river. It's famous with fishermen during cooler hours, but just upstream from this view the river leaves the side of Montana Highway 84 and enters the roadless Bear Trap Canyon Wilderness, with class IV whitewater for the more adventurous. More ancient stone can be seen in the stonemasonry inside Bozeman Yellowstone International Airport. Photo taken on August 6, 2016.
 
Photo Details: Camera Maker: OLYMPUS; Camera Model: VR340,D750 ; Focal Length: 15.2mm (35mm equivalent: 86mm); Aperture: ƒ/5.0; Exposure Time: 0.0016 s (1/640); ISO equiv: 100; 16 megapixel 10X wide optical zoom; 4.2-42mm; Software: Adobe Photoshop CS3 Windows.