Lava Pillow Lava Photo by Steve Mattox, 1988. Aa lava on pahoehoe, Hilina Pali, Kilauea. Photograph by J.D. Griggs, U.S. Geological Survey, June 15, 1989. Pahoehoe lava, Kilauea, Hawaii.
Pahoehoe lava is characterized by a smooth, billowy, or ropy surface.
A ropy surface develops when a thin skin of cooler lava at the surface of the flow is pushed into folds by the faster moving, fluid lava just below the surface.