Rock-cut basin
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A rock-cut basin is a natural cylindrical depression cut into stream or river beds, often filled with water. Such plucked-bedrock pits are created by kolks; powerful vortices within the water currents
The Caaf Water running over limestone: a good site for rock-cut basins.
Men-an-tol and the 'holed stone' which may have been a rock-cut basin
A bullaun made from rock-cut basins in Chapeltoun, Ayrshire, Scotland
Small basins cut by pebbles in fast moving water near the edge of the waterfall
Kolk (vortex)
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A kolk is an underwater vortex causing hydrodynamic scour by rapidly rushing water past an underwater obstacle. High-velocity gradients produce a high-shear rotating column of water, similar to a torn
Rock-cut basin
…A rock-cut basin is a natural cylindrical depression cut into stream or river beds, often filled with water. Such plucked-bedrock pits are created by kolks; powerful vortices within the water currents which spin small boulders around, eroding out these rock basins by their abrasive action. These basins are…
One of many kolk-formed depressions or "potholes" in the channeled scablands in eastern Washington at 46°54′21.40″N 119°16′47″W / 46.9059444°N 119.27972°W / 46.9059444; -119.27972.
Kolk from the 1717 Christmas flood in Horumersiel (de: Horumersiel) with information board