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columnar jointing

(in basaltic igneous rocks) a series of generally hexagonal columns formed by vertical joints as a result of contraction during cooling. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for columnar jointing
  • You'll see quartz and feldspar and a great example of columnar jointing that forms a natural staircase.
  • columnar jointing, as this formation is called, is another result of the rapid cooling of magma.
  • Vertical borings do not disclose the nature of columnar jointing.
  • columnar jointing in the lava fans out to meet the canyon wall, staying perpendicular to the cooling surface.
  • Good columnar jointing and other geologic formations.

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