A lava coil is a spiral or scroll-shaped lava formation occurring when relatively low viscosity lava such as Pahoehoe solidifies along a slow-moving shear zone in the flow.
The shear produces a Kelvin–Helmholtz instability that forms spiral-shaped patterns.
Depending on the side of the flow the spiral is clockwise or anti-clockwise.
They have been observed on flows near Kilauea on Hawai'i,[1] in Kenya[2] and possibly on Mars.
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