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Radiating Pattern of Joints in a Lava Flow / Grand Canyon
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Photographer: Ron Wolf
ID: 0000 0000 0812 0607 (2012-08-12)Copyright © 2012 Ron Wolf
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INFORMATION PROVIDED WITH THE PHOTO
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date of photo May 26, 2012
location
Along the Colorado River. Grand Canyon National Park (Coconino County, Arizona, US)notes Tributaries into the Grand Canyon from the North Rim provided channels for a series of basalt flows from the Uinkaret volcanic field on the Kaibab Plateau. Eruptions occurred during four separate periods beginning about 700,000 years ago, after the canyon was already well developed. At one point, these flows filled the canyon to a depth of 1500 feet. As a lava flow cools and solidifies, the rock contracts, forming a pattern of joints. The jointing develops perpendicular to the cooling surface. When the flow is relatively flat and the cooling ocurs evenly, the jointing creates a pattern of vertical columns. The radiating columns seen here develop when lava drains from the flow toward the end of an eruptive cycle to leave long tubes and tunnels or channels are eroded into the surface of a flow. When those lava tubes or channels are filled anew during a later eruptive cycle, the highly irregular shape of the cooling surfaces promote jointing in these radiating patterns.camera Canon EOS Rebel T3i, 85mm, f/14, 1/320 sec.
photo category: Misc. - geology
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Using this photo The thumbnail photo (128x192 pixels) on this page may be freely used for personal or academic purposes without prior permission under the Fair Use provisions of US copyright law as long as the photo is clearly credited with © 2012 Ron Wolf.
For other uses, or if you have questions, contact Ron Wolf RonWolf[AT]EyeOnNature.com. (Replace the [AT] with the @ symbol before sending an email.) |
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