Using syrup and baking soda, research has revealed how rootless cones, which are small volcanic formations found on Earth and Mars, are created. The study, conducted through experimental methods, shows that a process of self-organization governs how these landforms are distributed and their sizes. This work will improve our understanding of explosive eruptions that occur when lava interacts with water, while also providing new insights into geological processes on the red planet.
Research at Niigata University utilized syrup and baking soda to explain the mechanism behind rootless cone formation, small volcanic structures typically seen on Earth and Mars. The experimental study revealed that the distribution and size of these landforms are determined by a self-organization process. This research will advance our knowledge of explosive eruptions, particularly those resulting from lava-water interactions, and will shed new light on geological activities on Mars.
Rootless cones are small volcanic landforms with diameters varying from a few meters to several hundred meters, created by repeated explosions that occur when surface lava interacts with water sources like lakes and rivers. Unlike standard volcanoes that form from magma rising from deep within the Earth, rootless cones develop when lava covers a layer containing water, leading to explosive reactions, thus earning the name pseudocraters. While Iceland has numerous rootless cones, they are quite rare in other regions; a few can be spotted along the coast of Hawaii’s Big Island. However, Mars has extensive fields of rootless cones, making their formation a key interest in planetary geology.
Associate Professor Rina Noguchi and her student Wataru Nakagawa from Niigata University conducted laboratory experiments to replicate the formation of rootless cones. They utilized heated starch syrup as a substitute for lava and a mix of baking soda and cake syrup to mimic a water-rich layer.
In nature, lava reaches temperatures over 1000°C, causing water to vaporize and expand violently. Conversely, starch syrup only reaches around 140°C before it caramelizes, which isn’t enough to trigger water vaporization. To address this limitation, the researchers leveraged the thermal decomposition of baking soda—something commonly seen in making karumeyaki (Japanese honeycomb toffee)—to boost foaming. When heated by the starch syrup, the baking soda (sodium bicarbonate) releases carbon dioxide, enhancing the foaming and mimicking explosions akin to those that form rootless cones. Cake syrup was added to modify the viscosity. The team varied the syrup thickness in a beaker and closely monitored the size and number of openings created.
“We found that conduits frequently failed to retain their structure because they were disrupted by others forming nearby,” stated Assoc. Prof. Noguchi. The research indicated that competition among conduits, alongside water competition, significantly affects the spatial distribution of rootless cones. Thicker syrup layers resulted in increased competition among conduits, leading to more failures, which aligns with observations on Mars where thicker lava corresponds with fewer rootless cones. In contrast, environments abundant in conduits (signaling many rootless cones) experienced reduced explosions due to limited water access, resulting in smaller cone structures. This perspective aligns with observations on Mars indicating that regions with thin lava lack features resembling rootless cones.
Additionally, the failed conduits observed in lava areas on Earth support the notion that conduit competition universally influences the formation of rootless cones. These experiments and geological evidence emphasize that the merging and splitting of conduits influenced by lava thickness are critical in determining the spatial distribution and size of rootless cones.
The results provide a better understanding of how rootless cones form on Earth and also enhance our knowledge about similar geological features on other planets, especially Mars. Future research will aim to combine detailed field studies with remote sensing data to refine formation models and improve the understanding of historical environmental conditions related to rootless cone development.
