The basalt columns at San-Shi-Bi were exposed due to human intervention during road construction rather than solely natural erosion.
The hexagonal structure is caused by the contraction of lava as it cooled rapidly in contact with air or water.
These formations are part of the Penghu Archipelago's complex volcanic history dating to the Miocene epoch.
The site displays a distinct 'staircase' appearance caused by the layering of different lava flows.
Unlike some popular basalt sites, the formations here are situated closer to ground level, allowing for eye-level viewing of the column cross-sections.
San-Shi-Bi, or the Three Stone Walls, is a prominent geological site located in Xiyu Township, Penghu, featuring exposed columnar basalt formations. The site is characterized by vertical hexagonal basalt columns created by volcanic activity and subsequent cooling. It serves as a smaller, more secluded alternative to the larger Daguoye Columnar Basalt. Visitors can observe the distinct geometric shapes of the rock layers which were revealed following the excavation of land for local construction. The location is an integrated part of the Penghu Penghu Marine National Park and geological trail network. These basalt columns are estimated to date back approximately 8 to 17 million years.
Position yourself at the base of the tallest wall to capture the verticality and repeating geometric patterns of the columns.
Wear sturdy, closed-toe walking shoes to navigate the uneven, rocky terrain surrounding the basalt walls.
Carry plenty of drinking water and sun protection as the site lacks natural shade.
Visit during low tide if you plan to explore the adjacent coastal areas, as the water level changes significantly.
Attempting to climb the vertical rock faces; the basalt can be unstable and crumbly.
Do not climb on the basalt columns or remove any rock fragments, as the site is a protected geological asset.
