Rock balancing (also stone balancing, or stacking) is a form of recreation or artistic expression in which rocks are piled in balanced stacks, often in a precarious manner. Conservationists and park services have expressed concerns that the arrangements of rocks can disrupt animal habitats, accelerate soil erosion, and misdirect hikers in areas that use cairns as navigation waypoints. Rock piling in protected wilderness has been considered vandalism by some park services. Process During the 2010s, rock balancing became popular around the world, popularised through images of the rocks being shared on social media. Balanced rocks vary from simple stacks of two or three stones, to arrangements of round or sharp stones balancing in precarious and seemingly improbable ways. Professional rock-balancing artist Michael Grab, who can spend hours or minutes on a piece of rock balancing, says that his aim when stacking the stones is "to make it look as impossible as possible", and that the larger the size of the top rock, the more improbable the structure looks. People often assume that Grab has composed his structures using glue or support rods, or photoshopped the final result. Grab describes the physical process of balancing rocks as "basically looking for points where they lock on one another", saying that three points of contact are required between stones, with the placed rock's center of mass having to be between those points for it to balance. He tests the stability of his finished sculptures by splashing them with water, judging that if they survive that process, they are worthy to be photographed. Japanese rock balancer Ishihana-Chitoku is interested in rock balancing sculptures in terms of their overall silhouettes. He considers the shapes and colors of the rocks used, and their effect on the sculpture's contours. Chitoku starts his sculptures by selecting a stone to be placed at the top, and building up to it. Michael Grab has said that in his experience balanced stones may stand for "months" if undisturbed, and that he knocks his rock piles over himself, once he has photographed and documented them. Motivations Balancing rocks is seen by those who perform it as a meditative and creative activity, with artists saying that the process of physically handling and balancing the stones provides them with mental health benefits. Some compare the impermanence of the structures to zen buddhism. Rock balancing is also undertaken competitively, with events and festivals including the