Observing gravels included in Baekuiri Layer, it can be seen that they are arranged in a certain direction and this shows the direction of water flow of old Hantan River.
In Cheorwon and Pocheon including Yeoncheon, unconsolidated sediments are distributed under the hardened basaltic layer and this sedimentary layer is called Baekuiri Layer. Baekuiri Layer is mostly conglomerate bed with many gravels and some sand layer and mud layer are also placed under basalt.
This Baekuiri Layer is a very unusual phenomenon observed only in Hantan River and Imjin River in Korea and corresponds to a geological attraction with very high educational value.
That Baekuiri Layer was covered with Cenozoic Quaternary basalt indicates that the flow path of present Hantan River was different from that of old Hantan River. At that time, deposits forming present Baekuiri Layer may have been deposited in old Hantan River and thick basalt layer was formed as lava flowed into the stream channel of this old Hantan River. And then, over time, basalt was eroded and weathered and formed the stream channel of Hantan River, developing current Hantan River.
Observing gravels included in Baekuiri Layer, it can be seen that they are arranged in a certain direction and this shows the direction of water flow of old Hantan River.