How rock erosion by dissolution creates sharp shapes

Publication of the RDP in the journal PNAS on November 21, 2023. News by CNRS Engineering on December 7, 2023. Water flowing over soluble rocks can create patterns of multiple troughs bordered by sharp ridges. By combining field measurements, a numerical model and laboratory experiments, a team led by the MSC laboratory (CNRS/Université Paris Cité), in collaboration with the LPG (CNRS/Nantes Université/Université d'Angers) and the RDP (CNRS/ENS de Lyon/Inrae) has shown that the appearance of these shapes results from a geometric mechanism. The results are published in the journal PNAS . Why are crests and spikes so often observed in nature when soluble rocks are dissolved by the action of water flow? In particular, concave depressions delimited by sharp crests called scallop patterns can be found on the walls of underground caves. Here, we show that the emergence of the spikes and crests is explained in a general way by a geometrical mechanism describing the evolution of a receding interface.