The surface of lava flow will be cooled down and solidified during the process. The part of lava surface will undergo pushing, twisting and rotating to different degrees, thus forming ropy or twisting surface after cooling. Generally, the arcuate protruding direction of ropy surface points to the flowing direction of lava. The pahoehoe has low viscosity and is easy to flow. Its flow velocity ranges between 0-30 km/h. The surface of pahoehoe lava have various forms, but the ropy, wavy and smooth pahoehoe lava are very common in Jingpohu area.