The peaks of the so-called stone forests were formed by natural dissolution of the rocks in the water and related currents

Part of the Stone Forest in Shilin, China. Photo: Dcpeets / <a href=""target="_blank">Wikimedia Commons</a>, <a href=""target="_blank">Creative Commons License</a>

Scientists from New York University simulated the chemical and mechanical processes

Stone forests – pointed rock formations resembling trees in regions of China, Madagascar, and many other locations worldwide – are as majestic as they are mysterious, created by uncertain forces that give them their shape. A team of scientists from New York University has now shed new light on how these natural structures are created.

The scientific results also may help to better manufacture sharp-tipped structures, such as the micro-needles and probes needed for scientific research and medical procedures.

Through a series of simulations and experiments, the scientists showed how flowing water carves ultra-sharp spikes in landforms. The study also illuminates a mechanism that explains the prevalence of sharply pointed rock spires in karst—a topography formed by the dissolution of rocks, such as limestone.
In their study, the scientists simulated the formation of these pinnacles over time through a mathematical model and computer simulations that took into account how dissolving produces flows and how these flows also affect dissolving and thus reshaping of a formation.

In several simulations, the scientists replicated the formation of these natural structures by creating sugar-based pinnacles, mimicking soluble rocks that compose karst and similar topographies, and submerging them in tanks of water. Interestingly, no flows had to be imposed, since the dissolving process itself created the flow patterns needed to carve spikes.

The results from Lab experiments reflected those of the simulations, thereby supporting the accuracy of the researchers’ model. The authors speculate that these same events happen – albeit far more slowly – when minerals are submerged under water, which later recedes to reveal stone pinnacles and stone forests.

Co-authors of the study were Leif Ristroph, an associate professor at New York University’s Courant Institute of Mathematical Sciences, Jinzi Mac Huang, an NYU doctoral student at the time of the research, and Joshua Tong, an NYU undergraduate at the time of the study. Included in the research team was also Michael Shelley, professor at the Courant Institute.

Source: New York University

Proceedings of the National Academy of Sciences (PNAS)

This false-color photograph shows a “forest” of many candy pinnacles that have been dissolved in water. The candy was initially a solid block containing pores, which the dissolving process has reshaped into a bed-of-nails formation. Image courtesy of NYU's Applied Mathematics Lab.

(17.09.2020, USA: 09.17.2020)