Columnar structure Meaning, Definition & Usage

Definitions
  1. (Geol.), a structure consisting of more or less regular columns, usually six-sided, but sometimes with eight or more sides. The columns are often fractured transversely, with a cup joint, showing a concave surface above. This structure is characteristic of certain igneous rocks, as basalt, and is due to contraction in cooling.
Definitions
  1. . See under Columnar.

Webster 1913