Yonghwasan (Gangwon Peace Area National Geopark)

Granite is a plutonic rock formed when magma solidifies deep underground. Rocks formed under high-temperature and high-pressure conditions deep underground undergo 'weathering,' a process that easily breaks them down as they rise near the surface where temperature and pressure decrease. In particular, weathering actively occurs when rocks come into contact with moisture underground. This is a type of chemical weathering (a phenomenon in which the bonds of minerals composing rocks are loosened and crumbled) and is called deep weathering (or chemical deep weathering) because it occurs underground.

When deep weathering accelerates, even hard rocks become weak enough to be easily broken by human hand strength, and the material produced in this process is called saprolite. However, granite that has undergone little or no weathering becomes exposed above the ground, and because the time of contact with moisture is short, it no longer undergoes further deep weathering, forming large-scale rock mountains. In other words, Yonghwasan is a rock mountain formed as follows: after deep weathering, the weakened material (saprolite) was washed away, and large dome-shaped rock masses with few fracture structures were exposed on the surface, creating the current rock mountain.