Archive - Unconformity at Frijoles Canyon in Bandelier National Monument

July 22, 2018


Each Sunday we present a notable item from our archives. This EPOD was originally published
July 26, 2012.

: Rick Scott 
Summary Author: Rick Scott

The geologic unconformity shown in this photo, taken in Frijoles Canyon at Bandelier National Monument, New Mexico, is the result of volcanic processes. The numerous thin layers had been formed by deposition from a maar volcano. They were on the order of 2 in to 6 in (5 cm to 15 cm) wide and looked like a layer cake.  Initially, rising lava from the volcano encountered water causing a steam explosion. Lava and existing rock were then thrown into the air and deposited as these thin layers. The edge of the unconformity that slopes downward to the left is the surface of the volcano's crater. Rock above the crater's surface was at one time a lava pool that solidified. Above this is a layer of basalt from an overlying lava flow. Photo taken on June 21, 2012. 

Photo Details: Camera: Canon PowerShot G1 X; Lens: 15.1-60.4 mm; Focal Length: 41.337mm; Focus Distance: 64.4m; Aperture: f/5.6; Exposure Time: 0.017 s (1/60); ISO equiv: 100; Software: Adobe Photoshop CS5 Windows.