An Unexplained Feat of Dry Stone Engineering
In the valley between the twin peaks of Mount Maisan sits Tapsa Temple, the "Pagoda Temple." The site is famous for a collection of more than 80 conical stone pagodas constructed without mortar or mechanical assistance. This feat was accomplished by a single person, the hermit Yi Gap-ryong (1860-1957), who began his work in 1885 at the age of 25. Over a period of 30 years, he built approximately 120 of these structures, of which around 80 remain intact. The pagodas vary in height, with some reaching up to 9 meters (30 feet) and the tallest, a pair of towers behind the main temple hall, standing at 15 meters.
The construction method is a scientific curiosity. The stones, gathered from local sources and from rivers and mountains across Korea, were piled one by one. The technique involved creating a circular base, placing more stones inside this ring, and then building upwards in a conical shape. Small pebbles fill the gaps between the larger stones to add stability. Despite this seemingly simple dry-stacking method, the pagodas have withstood powerful typhoons and harsh weather for over a century, a phenomenon that has puzzled engineers. Standard structural analysis suggests that such dry-stacked towers, especially at their height, should not be able to resist the lateral forces generated by strong winds.
The Physics of Stability
The resilience of the Tapsa pagodas is an ongoing subject of study. The structures are built directly onto the bedrock of the mountain, providing a solid foundation. Yi Gap-ryong is said to have followed the principles of the "eight progressive positions of Zhuge Liang," a method that involves specific circular and conical configurations. This technique, combined with the careful placement of smaller pebbles to interlock the larger stones, creates a structure that can subtly shift and dissipate energy from wind and seismic activity.
Each stone is precisely balanced, and the conical shape gives the structures a low center of gravity. While modern seismic studies on Korean stone pagodas often focus on structures with different construction methods, they confirm that stacked stone monuments are vulnerable to lateral forces, with sliding and rocking being primary modes of failure. The upper sections, with less load and smaller contact areas, are typically the most susceptible to sliding. The Tapsa pagodas, however, defy these expectations. Their endurance without any binding agents remains evidence of the builder's intuitive understanding of physics and materials, a level of skill that modern science has yet to fully replicate or explain. The unique geology of Maisan, with its tafoni formations—honeycomb-like weathering patterns on the rock faces—adds to the atmosphere of the site.