Keyword "PIPING" in:

Self-organized system of underground conduits originated by groundwater flow along fractures in quartz sandstone in Střeleč quarry
Soukup,J., Bruthans,J., Světlík,D., Schweigstillová,J., Smutek,D., volume 46, 2013 (GRR for 2012), pages 296–304
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