Order and disorder in columnar joints

TL;DR

This paper investigates the formation and patterning of columnar joints in cooling basalt and desiccating starch, revealing how boundary conditions influence their scale, order, and disorder, with implications for understanding geological and material processes.

Contribution

It demonstrates how boundary conditions affect pattern coarsening and disorder in columnar joints, providing new insights into their formation mechanisms and statistical properties.

Findings

Surface boundary conditions influence columnar pattern scale.

Constant drying power leads to power law coarsening.

Discontinuous pattern scale transitions occur under fixed conditions.

Abstract

Columnar joints are three-dimensional fracture networks that form in cooling basalt and several other media. The network organizes itself into ordered, mostly hexagonal columns. The same pattern can be observed on a smaller scale in desiccating starch. We show how surface boundary conditions in the desiccation of starch affect the formation of columnar joints. Under constant drying power conditions, we find a power law dependence of columnar cross-sectional area with depth, while under constant drying rate conditions this coarsening is eventually halted. Discontinuous transitions in pattern scale can be observed under constant external conditions, which may prompt a reinterpretation of similar transitions found in basalt. Starch patterns are statistically similar to those found in basalt, suggesting that mature columnar jointing patterns contain inherent residual disorder, but are statistically scale invariant.