Kolk

A kolk (colc) is an underwater vortex created when rapidly rushing water passes an underwater obstacle in boundary areas of high shear. High velocity gradients produce a violently rotating column of water, similar to a tornado. Kolks can pluck multi-ton blocks of rock and transport them in suspension for thousands of metres.

Kolks leave clear evidence in the form of plucked-bedrock pits, called rock-cut basins or kolk lakes and downstream deposits of gravel-supported blocks that show percussion but no rounding.

Examples

Kolks were first identified by the Dutch, who observed kolks hoist several ton blocks of riprap from dikes and transport them away suspended above the bottom.

Kolks are credited with creating the pothole-type geographical features in the highly jointed basalts in the channeled scablands of the Columbia Basin region in eastern Washington. Depressions were scoured out within the scablands that resemble virtually circular steep-sided potholes. Examples from the Missoula Floods in this area include:

KOLK

KOLK 94.3 FM is a radio station licensed to Lakeside, Montana. The station broadcasts a Country music format and is owned by KOFI, Inc.

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