Flute casts are scoop-shaped structures on the soles (undersides) of beds. They are features representing sediments that filled depressions on the immediately subjacent bedding plane. Flute casts form by erosive scour. The most common geologic phenomena that produce flute casts are turbidity currents (underwater sediment slides). Sedimentary rocks representing deposition by ancient turbidity currents are called turbidites. Many turbidite successions have well preserved flute casts.
Flute casts can provide current directions (= upslope-downslope directions). The scoop-shaped end of each flute cast points up-current (see below).
Flute casts on the sole of a mudrock (12.8 cm across at its widest). The turbidity current that produced this moved from left to right (>>>>>>). This sample is from a turbidite flysch succession in an ancient foreland basin setting. Stratigraphy & age: β3 or β4 member (sensu Enos, 1969 - Geological Society of America Special Paper 117), Cloridorme Formation, Caradocian, Ordovician. Locality: shoreline cliff at St. Yvon, northeastern Gaspˇ Peninsula, northern East Gaspˇ County, Quebec, Canada.