Puzzling Honeycomb Pattern on Czech Rock Formation Solved via Computer Simulations: Moisture and Salt, Study Says

Scientists were able to determine that moisture and salt were the cause of the puzzling honeycomb pattern on a rock formation in the Czech Republic through the use of computer simulations.

Puzzling Honeycomb Pattern on a Czech Rock Formation

In terms of geology, honeycombs are a fascinating pattern of tiny spaces on rock surfaces that can be found on Mars and in coastal, wet, and arid climates.

They are a pain in old structures and monuments yet intriguing to look at in natural objects.

The origin of honeycombs is still a mystery to scientists despite a century of inquiry.

The intriguing hollows-and-ridges pattern is replicated by a computer simulation of rock weathering in a study by two Skoltech researchers, which also identifies the factors that favor or inhibit its production.

Saltwater evaporation is the principal element at work.

Despite intensive research over the past century, the formation of honeycomb patterns on rock faces remains a mystery, according to the study's primary author, Associate Professor Alexander Safonov of Skoltech Materials.

Numerous theories link wind and water erosion, the creation of ice and salt crystals, abrupt temperature changes, and even fungi to the formation of honeycombs.

Goldilocks Zone and Computer Simulations

According to Safonov, their study used the seawater evaporation concept, numerically simulated the process, and identified the "Goldilocks zone"-a region that is neither too dry nor too wet-where honeycomb erosion occurs.

Estimating the expected lifespan of a projected structure is yet another possibility. In terms of monument conservation, the results may help pinpoint the specific spots on historic buildings, statues, etc. that are most susceptible to honeycomb erosion, as well as determine safer locations for setting these objects.

Rock can be damaged by all known types of weathering, but up until recently, no mathematical model or laboratory experiment could replicate the complicated web of voids that characterizes honeycomb weathering.

Furthermore, the simulation even explains the distinctive smooth rock face that is frequently visible below the worn zone and above it.

Moisture and Salt Crystals

The 2D simulation, based on standard evaporation conditions, maintains constant moisture deep within the rock due to its ability to draw water from the soil, as observed in Apolena Rock City, Czech Republic.

Moisture content in the rock's inner layers varies based on its height above the ground due to gravity. Honeycombs emerge when initial rock dents align with specific moisture levels.

Water doesn't always evaporate on the surface; there are three scenarios. Higher up, slow sub-surface evaporation with minimal salt formation occurs.

These insights come from co-author Kirill Minchenkov, a Skoltech Ph.D. student, highlighting that water's behavior in rock is more complex than surface evaporation.

Minchenkov noted that erosion didn't occur. Conversely, in wetter conditions near the ground or sea, intense surface evaporation leaves salt deposits without harming the rock.

However, an intermediate scenario involves moderate-depth evaporation, leading to salt deposits slightly below the surface, causing rock erosion.

Honeycomb formation results from the interplay of these scenarios. While the entire rock face may align with the ideal conditions, any initial protrusions exaggerate due to being "too dry."

Beneath them, deeper evaporation causes less erosion, preserving the protrusions as surrounding rock erodes. In very wet rocks, only the protrusions erode, resulting in a smooth rock face seen beneath natural honeycombs closer to sea level.