Formation of columnar basalt jointing resembles mud cracks

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Description: Mudcracks form when muddy sediment is exposed to the atmosphere and dries up. They have a characteristic polygonal shape when viewed from above, http://www.umt.edu/geosciences/faculty/hendrix/g100/L6B.html. How is this process similar for cooling basalt?
Uploaded by: MaryAnn McGarry
Created: Monday, 24 October 2011, 7:34 AM
Last modified: Tuesday, 25 October 2011, 11:24 AM
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