Devil's Postpile Tile Pattern

June 13, 2011

Devilspostpiletiles 
Photographer: Nel Graham
Summary Author: Nel Graham

June 2011 Earth Science Picture of the Day Viewer's Choice

A short hike to the top of the Devil's Postpile on Mammoth Mountain, in the Sierra Nevada's of California, reveals the tile-like pattern shown above. Slow cooling of basalt, from the top down, is responsible for these nearly 120 degree shrinkage cracks. The top of the "posts" were scoured by glaciers during the last glaciation. Visible on the tiles faces are glacial striations, which show the direction of motion of the glacier. A water bottle was placed for scale purposes. Photo taken in July 2008.

Photo details: Camera Maker: Panasonic; Camera Model: DMC-TZ4; Focal Length: 4.7mm (35mm equivalent: 28mm); Aperture: f/8.0; Exposure Time: 0.0031 s (1/320); ISO equiv: 100; Exposure Bias: none; Metering Mode: Matrix; Exposure: program (Auto); White Balance: Auto; Flash Fired: No (enforced); Orientation: Normal; Color Space: sRGB.