“…Developments in physical and numerical modelling of supercritical‐flow bedforms (Kennedy, ; Jorritsma, ; Foley, ; Winterwerp et al ., ; Parker & Izumi, ; Alexander et al ., ; Fagherazzi & Sun, ; Sun & Parker, ; Taki & Parker, ; Fildani et al ., ; Kostic & Parker, ; Alexander, ; Sequeiros et al ., ; Spinewine et al ., Kostic et al ., ; Paull et al ., ; Cartigny et al ., , ; Kostic, ; Balmforth & Vakil, ) have sparked a large number of observations of supercritical‐flow bedforms in modern systems (Fildani et al ., ; Lamb et al ., ; Duarte et al ., ; Jobe et al ., ; Babonneau et al ., ; Maier et al ., ; Covault et al ., ; Hughes Clarke et al ., ; Fricke et al ., ; Tubau et al ., ; Zhong et al ., ; Normandeau et al ., ; Symons et al ., ). Despite this common and well‐documented occurrence of supercritical‐flow bedforms, outcrop examples of deposits indicating these flow conditions in a fluvial setting (Fielding, ; Duller et al ., ; Fielding et al ., ; Ghienne et al ., ; Lang & Winsemann, ) or in a (deltaic‐) marine setting (Postma et al ., , ; Ventra et al ., ; Dietrich et al ., ) are sparse. The recent flurry of recognition of supercritical bedforms in modern environments makes it implausible that sedimentary structures indicative of these bedforms should be rare in deposits formed in comparable ancient environments.…”