Columnar structure


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(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.<- as="" at="" giant's="" causeway,="" ireland="" -="">
See under Columnar.

See also: Columnar, Structure

References in classic literature ?
360) has compared the fissures by which the columnar structure seems to be determined, to the joints that traverse nearly all rocks, but which are best seen in the non-stratified masses.
It is a columnar structure with the preferential growth direction nearly parallel to axis of the ingot, showing coarsening of the primary dendrite arms and disappearance of the secondary dendrite arms for holding at high temperature after solidification.
An obvious columnar structure is observed in Figures 7(a), 7(b), and 7(c), wherein small amount of Cu exists.
TiN (1.2 [micro]m thick, dense columnar structure, Fm3m cell with lattice parameter of 4.276 [Angstrom], grain size of ~16 nm, and effective elastic modulus of 600 GPa) shown in Figure 1(a) with the hardness of 28 GPa and [Al.sub.28][Ti.sub.20][N.sub.52] (1.2 [micro]m thick, dense columnar structure, Fm3m cell with lattice parameter of 4.188 [Angstrom], grain size of ~13 nm, and effective elastic modulus of 580 GPa) shown in Figure 1(b) with the hardness of 28 GPa exhibited picture frame cracking on the edges of the imprint and inside the imprint itself due to low fracture resistance of both coatings.
This process results in the columnar structure grinding and in nucleation of the grains with different textures [14].
The results show that the coatings topography was dominated by domes and craters which were uniformly distributed over the surface, and all coatings showed a columnar structure. Damage mechanisms under microindentation and scratch depended on coatings structure and composition.
In Figure 6 (a and b) are shown the experimental measurements of the variation of the primary and secondary dendrite arm spacings as a function of distance from the metal/mold interface, the restricted region with columnar structure.
The prismatic layer takes on typical multilevel structure consisting of columnar structure on the whole, and adjacent columnar structure intersects vertically, presenting a typical crossed lamellar structure (see Figures 12(b)-12(c)).
Typical self-assembled columnar structure of the ZnO films perpendicular to the glass substrate and with a hillock surface morphology was observed.
By using the columnar structure, a gain variation of less than 1.1 dB was achieved in the azimuthal plane.
James, "Factors producing columnar structure in lavas and its occurrence near Melbourne, Australia," Journal of Geology, vol.