| 초록 |
In Yakushima, granitic and sedimentary boulders are cracked polygonally on their surface. They are called Kikkou-boulders', which mean polygonal pattern in Japan. The size of the polygonal pattern is proportional to the size of the Kikkou-boulder, therefore bigger boulder has bigger polygonal pattern. The Kikkou-boulders show a concentric crust and core structure. The depth of the polygonal cracking reaches the boundary between the crust and core structure. The characteristics of the Kikkou-boulders indicate that they are core-stones, which are ellipsoidal blocks separated from bedrock by the cause of weathering. It is also suggested that the polygonal cracking is generated from the weathering of the rock. |
