columnar jointing
geological structure where sets of intersecting closely spaced fractures, referred to as joints, result in the formation of a regular array of polygonal prisms, or columns
en-GB/kəlʌmnə ˈd͡ʒɔɪntɪŋ/
geological structure where sets of intersecting closely spaced fractures, referred to as joints, result in the formation of a regular array of polygonal prisms, or columns